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Pivonka P, Calvo-Gallego JL, Schmidt S, Martínez-Reina J. Advances in mechanobiological pharmacokinetic-pharmacodynamic models of osteoporosis treatment - Pathways to optimise and exploit existing therapies. Bone 2024; 186:117140. [PMID: 38838799 DOI: 10.1016/j.bone.2024.117140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/17/2024] [Accepted: 05/29/2024] [Indexed: 06/07/2024]
Abstract
Osteoporosis (OP) is a chronic progressive bone disease which is characterized by reduction of bone matrix volume and changes in the bone matrix properties which can ultimately lead to bone fracture. The two major forms of OP are related to aging and/or menopause. With the worldwide increase of the elderly population, particularly age-related OP poses a serious health issue which puts large pressure on health care systems. A major challenge for development of new drug treatments for OP and comparison of drug efficacy with existing treatments is due to current regulatory requirements which demand testing of drugs based on bone mineral density (BMD) in phase 2 trials and fracture risk in phase 3 trials. This requires large clinical trials to be conducted and to be run for long time periods, which is very costly. This, together with the fact that there are already many drugs available for treatment of OP, makes the development of new drugs inhibitive. Furthermore, an increased trend of the use of different sequential drug therapies has been observed in OP management, such as sequential anabolic-anticatabolic drug treatment or switching from one anticatabolic drug to another. Running clinical trials for concurrent and sequential therapies is neither feasible nor practical due to large number of combinatorial possibilities. In silico mechanobiological pharmacokinetic-pharmacodynamic (PK-PD) models of OP treatments allow predictions beyond BMD, i.e. bone microdamage and degree of mineralisation can also be monitored. This will help to inform clinical drug usage and development by identifying the most promising scenarios to be tested clinically (confirmatory trials rather than exploratory only trials), optimise trial design and identify subgroups of the population that show benefit-risk profiles (both good and bad) that are different from the average patient. In this review, we provide examples of the predictive capabilities of mechanobiological PK-PD models. These include simulation results of PMO treatment with denosumab, implications of denosumab drug holidays and coupling of bone remodelling models with calcium and phosphate systems models that allows to investigate the effects of co-morbidities such as hyperparathyroidism and chronic kidney disease together with calcium and vitamin D status on drug efficacy.
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Affiliation(s)
- Peter Pivonka
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, QLD 4000, Australia.
| | - José Luis Calvo-Gallego
- Departmento de Ingeniería Mecánica y Fabricación, Universidad de Sevilla, Seville 41092, Spain
| | - Stephan Schmidt
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, FL 32827, USA
| | - Javier Martínez-Reina
- Departmento de Ingeniería Mecánica y Fabricación, Universidad de Sevilla, Seville 41092, Spain
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2
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Yan X, Zhang Q, Ma X, Zhong Y, Tang H, Mai S. The mechanism of biomineralization: Progress in mineralization from intracellular generation to extracellular deposition. JAPANESE DENTAL SCIENCE REVIEW 2023; 59:181-190. [PMID: 37388714 PMCID: PMC10302165 DOI: 10.1016/j.jdsr.2023.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/01/2023] [Accepted: 06/13/2023] [Indexed: 07/01/2023] Open
Abstract
Biomineralization is a highly regulated process that results in the deposition of minerals in a precise manner, ultimately producing skeletal and dental hard tissues. Recent studies have highlighted the crucial role played by intracellular processes in initiating biomineralization. These processes involve various organelles, such as the endoplasmic reticulum(ER), mitochondria, and lysosomes, in the formation, accumulation, maturation, and secretion of calcium phosphate (CaP) particles. Particularly, the recent in-depth study of the dynamic process of the formation of amorphous calcium phosphate(ACP) precursors among organelles has made great progress in the development of the integrity of the biomineralization chain. However, the precise mechanisms underlying these intracellular processes remain unclear, and they cannot be fully integrated with the extracellular mineralization mechanism and the physicochemical structure development of the mineralization particles. In this review, we aim to focus on the recent progress made in understanding intracellular mineralization organelles' processes and their relationship with the physicochemical structure development of CaP and extracellular deposition of CaP particles.
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Affiliation(s)
- Xin Yan
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Institute of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Qi Zhang
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Institute of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Xinyue Ma
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Institute of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Yewen Zhong
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Institute of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Hengni Tang
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Institute of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Sui Mai
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Institute of Stomatology, Sun Yat-sen University, Guangzhou, China
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3
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Complications and Treatments in Adult X-Linked Hypophosphatemia. ENDOCRINES 2022. [DOI: 10.3390/endocrines3030047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is a rare inherited disorder involving elevated levels of fibroblast growth factor (FGF) 23, and is caused by loss-of-function mutations in the PHEX gene. FGF23 induces renal phosphate wasting and suppresses the activation of vitamin D, resulting in defective bone mineralization and rachitic changes in the growth plate and osteomalacia. Conventional treatment with combinations of oral inorganic phosphate and active vitamin D analogs enhances bone calcification, but the efficacy of conventional treatment is insufficient for adult XLH patients to achieve an acceptable quality of life. Burosumab, a fully human monoclonal anti-FGF23 antibody, binds and inhibits FGF23, correcting hypophosphatemia and hypovitaminosis D. This review describes a typical adult with XLH and summarizes the results of clinical trials of burosumab in adults with XLH.
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4
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Trombetti A, Al-Daghri N, Brandi ML, Cannata-Andía JB, Cavalier E, Chandran M, Chaussain C, Cipullo L, Cooper C, Haffner D, Harvengt P, Harvey NC, Javaid MK, Jiwa F, Kanis JA, Laslop A, Laurent MR, Linglart A, Marques A, Mindler GT, Minisola S, Yerro MCP, Rosa MM, Seefried L, Vlaskovska M, Zanchetta MB, Rizzoli R. Interdisciplinary management of FGF23-related phosphate wasting syndromes: a Consensus Statement on the evaluation, diagnosis and care of patients with X-linked hypophosphataemia. Nat Rev Endocrinol 2022; 18:366-384. [PMID: 35484227 DOI: 10.1038/s41574-022-00662-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/10/2022] [Indexed: 12/17/2022]
Abstract
X-linked hypophosphataemia (XLH) is the most frequent cause of hypophosphataemia-associated rickets of genetic origin and is associated with high levels of the phosphaturic hormone fibroblast growth factor 23 (FGF23). In addition to rickets and osteomalacia, patients with XLH have a heavy disease burden with enthesopathies, osteoarthritis, pseudofractures and dental complications, all of which contribute to reduced quality of life. This Consensus Statement presents the outcomes of a working group of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases, and provides robust clinical evidence on management in XLH, with an emphasis on patients' experiences and needs. During growth, conventional treatment with phosphate supplements and active vitamin D metabolites (such as calcitriol) improves growth, ameliorates leg deformities and dental manifestations, and reduces pain. The continuation of conventional treatment in symptom-free adults is still debated. A novel therapeutic approach is the monoclonal anti-FGF23 antibody burosumab. Although promising, further studies are required to clarify its long-term efficacy, particularly in adults. Given the diversity of symptoms and complications, an interdisciplinary approach to management is of paramount importance. The focus of treatment should be not only on the physical manifestations and challenges associated with XLH and other FGF23-mediated hypophosphataemia syndromes, but also on the major psychological and social impact of the disease.
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Affiliation(s)
- Andrea Trombetti
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
- Division of Geriatrics, Department of Rehabilitation and Geriatrics, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - Nasser Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | | | - Jorge B Cannata-Andía
- Hospital Universitario Central de Asturias (HUCA), Oviedo, Spain
- Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
- Retic REDinREN-RICORS, 2040-ISCIII, Madrid, Spain
| | - Etienne Cavalier
- Department of Clinical Chemistry, University of Liege, CHU de Liège, Liège, Belgium
| | - Manju Chandran
- Complicated Metabolic Bone Disorders Clinic, Osteoporosis and Bone Metabolism Unit, Department of Endocrinology, Singapore General Hospital, Singapore, Singapore
| | - Catherine Chaussain
- Université de Paris, Institut des maladies musculo-squelettiques, URP2496, UFR Odontologie, Montrouge, France
- AP-HP, FHU DDS-Net, Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphore, Service médecine bucco-dentaire, Hôpital Bretonneau, GH Paris Nord Université de Paris, Paris, France
| | - Lucia Cipullo
- Patient representative with XLH, Geneva, Switzerland
| | - Cyrus Cooper
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
- NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Dieter Haffner
- Department of Paediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Pol Harvengt
- XLH Belgium, Belgian association of patients with XLH (a member of the International XLH Alliance), Waterloo, Belgium
| | - Nicholas C Harvey
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | | | - Famida Jiwa
- Chair of the Committee of Patients Societies at the International Osteoporosis Foundation, Osteoporosis Canada, Toronto, Canada
| | - John A Kanis
- Mary McKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia
- Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Sheffield, UK
| | - Andrea Laslop
- Scientific Office, Federal Office for Safety in Health Care, Vienna, Austria
| | - Michaël R Laurent
- Centre for Metabolic Bone Diseases, University Hospitals Leuven, Leuven, Belgium
| | - Agnès Linglart
- Paris-Saclay University, INSERM U1185, Le Kremlin-Bicêtre, France
- AP-HP, endocrinology and diabetes for children, Reference centre for rare diseases of calcium and phosphate metabolism, OSCAR network, Platform of expertise for rare diseases of Paris Saclay Hospital, Bicêtre Paris Saclay Hospital, Le Kremlin-Bicêtre, France
| | - Andréa Marques
- Rheumatology Department, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal
- Health Sciences Research Unit: Nursing (UICiSA:E), Nursing School of Coimbra, Coimbra, Portugal
| | - Gabriel T Mindler
- Department of Paediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Salvatore Minisola
- Department of Clinical, Internal, Anaesthesiologic and Cardiovascular Sciences, 'Sapienza', Rome University, Rome, Italy
| | | | - Mario Miguel Rosa
- Departamento de Neurociências, Laboratório de Farmacologia Clínica E Terapêutica Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Germany
| | - Mila Vlaskovska
- Medical Faculty, Department of Pharmacology, Medical University Sofia, Sofia, Bulgaria
| | - María Belén Zanchetta
- Instituto de Investigaciones Metabólicas (IDIM), Universidad del Salvador, Buenos Aires, Argentina
| | - René Rizzoli
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland.
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Merz LM, Buerger F, Ziegelasch N, Zenker M, Wieland I, Lipek T, Wallborn T, Terliesner N, Prenzel F, Siekmeyer M, Dittrich K. A Case Report: First Long-Term Treatment With Burosumab in a Patient With Cutaneous-Skeletal Hypophosphatemia Syndrome. Front Endocrinol (Lausanne) 2022; 13:866831. [PMID: 35600592 PMCID: PMC9120998 DOI: 10.3389/fendo.2022.866831] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 03/18/2022] [Indexed: 11/28/2022] Open
Abstract
Epidermal nevus syndromes encompass a highly heterogeneous group of systemic disorders, characterized by epidermal nevi, and a spectrum of neuromuscular, ocular, and bone abnormalities. Cutaneous-skeletal hypophosphatemia syndrome (CSHS) constitutes a specific sub-entity in which elevated levels of fibroblast growth factor-23 cause hypophosphatemic rickets that are, to date, not amenable to causal therapy. Here, we report the first long-term follow-up of causal treatment with burosumab in a 3-year-old female patient with CSHS. 4 weeks after initiation of burosumab treatment, serum phosphate normalized to age-appropriate levels. Furthermore, long-term follow-up of 42 months revealed significant improvement of linear growth and gross physical functions, including respiratory insufficiency. Radiographic rickets severity as well as subjective bone pain were strongly reduced, and no side effects were observed over the course of treatment. In summary, we, here, report about a successful treatment of hypophosphatemic rickets in CSHS with burosumab over the time course of 42 months. In our patient, burosumab showed convincing efficacy and safety profile, without any loss of effect or increase of dose.
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Affiliation(s)
- Lea Maria Merz
- Department of Pediatric Nephrology and Pulmonology, University Hospital Leipzig, Leipzig, Germany
- *Correspondence: Lea Maria Merz,
| | - Florian Buerger
- Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Niels Ziegelasch
- Department of Pediatric Nephrology and Pulmonology, University Hospital Leipzig, Leipzig, Germany
| | - Martin Zenker
- Faculty of Medicine, University Hospital Magdeburg, Magdeburg, Germany
| | - Ilse Wieland
- Faculty of Medicine, University Hospital Magdeburg, Magdeburg, Germany
| | - Tobias Lipek
- Department of Pediatric Nephrology and Pulmonology, University Hospital Leipzig, Leipzig, Germany
| | - Tillmann Wallborn
- Department of Pediatric Nephrology, St. Georg Hospital, Leipzig, Germany
| | - Nicolas Terliesner
- Department of Pediatric Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Freerk Prenzel
- Department of Pediatric Nephrology and Pulmonology, University Hospital Leipzig, Leipzig, Germany
| | - Manuela Siekmeyer
- Department of Pediatric Nephrology and Pulmonology, University Hospital Leipzig, Leipzig, Germany
| | - Katalin Dittrich
- Department of Pediatric Nephrology and Pulmonology, University Hospital Leipzig, Leipzig, Germany
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Harada D, Ueyama K, Oriyama K, Ishiura Y, Kashiwagi H, Yamada H, Seino Y. Switching from conventional therapy to burosumab injection has the potential to prevent nephrocalcinosis in patients with X-linked hypophosphatemic rickets. J Pediatr Endocrinol Metab 2021; 34:791-798. [PMID: 33837680 DOI: 10.1515/jpem-2020-0734] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/08/2021] [Indexed: 12/18/2022]
Abstract
OBJECTIVES X-linked hypophosphatemic rickets (XLH) is a congenital fibroblast growth factor (FGF)23-related metabolic bone disease that is treated with active vitamin D and phosphate as conventional therapies. Complications of these therapies include nephrocalcinosis (NC) caused by excessive urine calcium and phosphate concentrations. Recently, an anti-FGF23 antibody, burosumab, was developed and reported to be effective in poorly-controlled or severe XLH patients. This study aimed to reveal the impact of switching treatments in relatively well-controlled XLH children with the Rickets Severity Scale less than 2.0. METHODS The effects of the two treatments in eight relatively well-controlled XLH children with a mean age of 10.4 ± 1.9 years were compared retrospectively for the same treatment duration (31 ± 11 months) before and after the baseline. RESULTS Actual doses of alfacalcidol and phosphate as conventional therapy were 150.9 ± 43.9 ng/kg and 27.5 ± 6.3 mg/kg per day, respectively. Renal echography revealed spotty NC in 8/8 patients, but no aggravation of NC was detected by switching treatments. Switching treatments increased TmP/GFR (p=0.002) and %TRP (p<0.001), and improved the high urine calcium/creatinine ratio to the normal range (p<0.001) although both treatments controlled disease markers equally. Additionally, low intact parathyroid hormone during conventional therapy was increased within the normal range by switching treatments. CONCLUSIONS Our results suggest that a high dose of alfacalcidol was needed to control the disease, but it caused hypercalciuria and NC. We concluded that switching treatments in relatively well-controlled XLH children improved renal phosphate reabsorption and decreased urine calcium extraction, and may have the potential to prevent NC.
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Affiliation(s)
- Daisuke Harada
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Kaoru Ueyama
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Kyoko Oriyama
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Yoshihito Ishiura
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Hiroko Kashiwagi
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Hiroyuki Yamada
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Yoshiki Seino
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
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7
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Laurent MR, De Schepper J, Trouet D, Godefroid N, Boros E, Heinrichs C, Bravenboer B, Velkeniers B, Lammens J, Harvengt P, Cavalier E, Kaux JF, Lombet J, De Waele K, Verroken C, van Hoeck K, Mortier GR, Levtchenko E, Vande Walle J. Consensus Recommendations for the Diagnosis and Management of X-Linked Hypophosphatemia in Belgium. Front Endocrinol (Lausanne) 2021; 12:641543. [PMID: 33815294 PMCID: PMC8018577 DOI: 10.3389/fendo.2021.641543] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/19/2021] [Indexed: 12/11/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is the most common genetic form of hypophosphatemic rickets and osteomalacia. In this disease, mutations in the PHEX gene lead to elevated levels of the hormone fibroblast growth factor 23 (FGF23), resulting in renal phosphate wasting and impaired skeletal and dental mineralization. Recently, international guidelines for the diagnosis and treatment of this condition have been published. However, more specific recommendations are needed to provide guidance at the national level, considering resource availability and health economic aspects. A national multidisciplinary group of Belgian experts convened to discuss translation of international best available evidence into locally feasible consensus recommendations. Patients with XLH may present to a wide array of primary, secondary and tertiary care physicians, among whom awareness of the disease should be raised. XLH has a very broad differential-diagnosis for which clinical features, biochemical and genetic testing in centers of expertise are recommended. Optimal care requires a multidisciplinary approach, guided by an expert in metabolic bone diseases and involving (according to the individual patient's needs) pediatric and adult medical specialties and paramedical caregivers, including but not limited to general practitioners, dentists, radiologists and orthopedic surgeons. In children with severe or refractory symptoms, FGF23 inhibition using burosumab may provide superior outcomes compared to conventional medical therapy with phosphate supplements and active vitamin D analogues. Burosumab has also demonstrated promising results in adults on certain clinical outcomes such as pseudofractures. In summary, this work outlines recommendations for clinicians and policymakers, with a vision for improving the diagnostic and therapeutic landscape for XLH patients in Belgium.
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Affiliation(s)
- Michaël R. Laurent
- Centre for Metabolic Bone Diseases, University Hospitals Leuven, Leuven, Belgium
- *Correspondence: Michaël R. Laurent,
| | - Jean De Schepper
- Division of Pediatric Endocrinology, KidZ Health Castle, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- Department of Pediatric Endocrinology, University Hospital Ghent, Ghent, Belgium
| | - Dominique Trouet
- Department of Pediatric Nephrology, Antwerp University Hospital, Antwerp, Belgium
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium
| | - Nathalie Godefroid
- Pediatric Nephrology, Cliniques Universitaires St. Luc (UCL), Brussels, Belgium
| | - Emese Boros
- Paediatric Endocrinology Unit, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Claudine Heinrichs
- Paediatric Endocrinology Unit, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Bert Bravenboer
- Department of Endocrinology, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Brigitte Velkeniers
- Department of Endocrinology, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Johan Lammens
- Department of Orthopaedic Surgery and Department of Development and Regeneration, Prometheus LRD Division of Skeletal Tissue Engineering, KU Leuven - University Hospitals Leuven, Leuven, Belgium
| | - Pol Harvengt
- XLH Belgium, Belgian X-Linked Hypophosphatemic Rickets (XLH) Patient Association, Waterloo, Belgium
| | - Etienne Cavalier
- Department of Clinical Chemistry, University Hospital Center of Liège, University of Liège, Liège, Belgium
| | - Jean-François Kaux
- Physical Medicine, Rehabilitation and Sports Traumatology, University and University Hospital of Liège, Liège, Belgium
| | - Jacques Lombet
- Division of Nephrology, Department of Pediatrics, University Hospital Center of Liège, Liège, Belgium
| | - Kathleen De Waele
- Department of Pediatric Endocrinology, University Hospital Ghent, Ghent, Belgium
| | - Charlotte Verroken
- Unit for Osteoporosis and Metabolic Bone Diseases, Department of Endocrinology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Koenraad van Hoeck
- Department of Pediatric Nephrology, Antwerp University Hospital, Antwerp, Belgium
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium
| | - Geert R. Mortier
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, Antwerp, Belgium
| | - Elena Levtchenko
- Department of Pediatrics/Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Johan Vande Walle
- Department of Pediatric Nephrology, University Hospital Ghent, Ghent, Belgium
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8
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Abstract
Great strides over the past few decades have increased our understanding of the pathophysiology of hypophosphatemic disorders. Phosphate is critically important to a variety of physiologic processes, including skeletal growth, development and mineralization, as well as DNA, RNA, phospholipids, and signaling pathways. Consequently, hypophosphatemic disorders have effects on multiple systems, and may cause a variety of nonspecific signs and symptoms. The acute effects of hypophosphatemia include neuromuscular symptoms and compromise. However, the dominant effects of chronic hypophosphatemia are the effects on musculoskeletal function including rickets, osteomalacia and impaired growth during childhood. While the most common causes of chronic hypophosphatemia in children are congenital, some acquired conditions also result in hypophosphatemia during childhood through a variety of mechanisms. Improved understanding of the pathophysiology of these congenital conditions has led to novel therapeutic approaches. This article will review the pathophysiologic causes of congenital hypophosphatemia, their clinical consequences and medical therapy.
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Affiliation(s)
- Erik Allen Imel
- Division of Endocrinology, Departments of Medicine and Pediatrics, Indiana University School of Medicine, 1120 West Michigan Street, Gatch Building Room 365, Indianapolis, IN, 46112, USA.
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9
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Haffner D, Emma F, Eastwood DM, Duplan MB, Bacchetta J, Schnabel D, Wicart P, Bockenhauer D, Santos F, Levtchenko E, Harvengt P, Kirchhoff M, Di Rocco F, Chaussain C, Brandi ML, Savendahl L, Briot K, Kamenicky P, Rejnmark L, Linglart A. Clinical practice recommendations for the diagnosis and management of X-linked hypophosphataemia. Nat Rev Nephrol 2020; 15:435-455. [PMID: 31068690 PMCID: PMC7136170 DOI: 10.1038/s41581-019-0152-5] [Citation(s) in RCA: 260] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
X-linked hypophosphataemia (XLH) is the most common cause of inherited phosphate wasting and is associated with severe complications such as rickets, lower limb deformities, pain, poor mineralization of the teeth and disproportionate short stature in children as well as hyperparathyroidism, osteomalacia, enthesopathies, osteoarthritis and pseudofractures in adults. The characteristics and severity of XLH vary between patients. Because of its rarity, the diagnosis and specific treatment of XLH are frequently delayed, which has a detrimental effect on patient outcomes. In this Evidence-Based Guideline, we recommend that the diagnosis of XLH is based on signs of rickets and/or osteomalacia in association with hypophosphataemia and renal phosphate wasting in the absence of vitamin D or calcium deficiency. Whenever possible, the diagnosis should be confirmed by molecular genetic analysis or measurement of levels of fibroblast growth factor 23 (FGF23) before treatment. Owing to the multisystemic nature of the disease, patients should be seen regularly by multidisciplinary teams organized by a metabolic bone disease expert. In this article, we summarize the current evidence and provide recommendations on features of the disease, including new treatment modalities, to improve knowledge and provide guidance for diagnosis and multidisciplinary care. In this Evidence-Based Guideline on X-linked hypophosphataemia, the authors identify the criteria for diagnosis of this disease, provide guidance for medical and surgical treatment and explain the challenges of follow-up.
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Affiliation(s)
- Dieter Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany. .,Center for Congenital Kidney Diseases, Center for Rare Diseases, Hannover Medical School, Hannover, Germany.
| | - Francesco Emma
- Department of Pediatric Subspecialties, Division of Nephrology, Children's Hospital Bambino Gesù - IRCCS, Rome, Italy
| | - Deborah M Eastwood
- Department of Orthopaedics, Great Ormond St Hospital for Children, Orthopaedics, London, UK.,The Catterall Unit Royal National Orthopaedic Hospital NHS Trust, Stanmore, UK
| | - Martin Biosse Duplan
- Dental School, Université Paris Descartes Sorbonne Paris Cité, Montrouge, France.,APHP, Department of Odontology, Bretonneau Hospital, Paris, France.,APHP, Reference Center for Rare Diseases of Calcium and Phosphate Metabolism, and Filière OSCAR, Paris, France
| | - Justine Bacchetta
- Department of Pediatric Nephrology, Rheumatology and Dermatology, University Children's Hospital, Lyon, France
| | - Dirk Schnabel
- Center for Chronic Sick Children, Pediatric Endocrinology, Charitè, University Medicine, Berlin, Germany
| | - Philippe Wicart
- APHP, Reference Center for Rare Diseases of Calcium and Phosphate Metabolism, and Filière OSCAR, Paris, France.,APHP, Department of Pediatric Orthopedic Surgery, Necker - Enfants Malades University Hospital, Paris, France.,Paris Descartes University, Paris, France
| | - Detlef Bockenhauer
- University College London, Centre for Nephrology and Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Fernando Santos
- Hospital Universitario Central de Asturias (HUCA), University of Oviedo, Oviedo, Spain
| | - Elena Levtchenko
- Department of Pediatric Nephrology and Development and Regeneration, University Hospitals Leuven, University of Leuven, Leuven, Belgium
| | - Pol Harvengt
- RVRH-XLH, French Patient Association for XLH, Suresnes, France
| | - Martha Kirchhoff
- Phosphatdiabetes e.V., German Patient Association for XLH, Lippstadt, Germany
| | - Federico Di Rocco
- Pediatric Neurosurgery, Hôpital Femme Mère Enfant, Centre de Référence Craniosténoses, Université de Lyon, Lyon, France
| | - Catherine Chaussain
- Dental School, Université Paris Descartes Sorbonne Paris Cité, Montrouge, France.,APHP, Department of Odontology, Bretonneau Hospital, Paris, France.,APHP, Reference Center for Rare Diseases of Calcium and Phosphate Metabolism, and Filière OSCAR, Paris, France
| | - Maria Louisa Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy
| | - Lars Savendahl
- Pediatric Endocrinology Unit, Karolinska University Hospital, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Karine Briot
- APHP, Reference Center for Rare Diseases of Calcium and Phosphate Metabolism, and Filière OSCAR, Paris, France.,Paris Descartes University, Paris, France.,APHP, Department of Rheumatology, Cochin Hospital, Paris, France.,INSERM UMR-1153, Paris, France
| | - Peter Kamenicky
- APHP, Reference Center for Rare Diseases of Calcium and Phosphate Metabolism, and Filière OSCAR, Paris, France.,APHP, Department of Endocrinology and Reproductive Diseases, Bicêtre Paris-Sud Hospital, Paris, France.,INSERM U1185, Bicêtre Paris-Sud, Paris-Sud - Paris Saclay University, Le Kremlin-Bicêtre, France
| | - Lars Rejnmark
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Agnès Linglart
- APHP, Reference Center for Rare Diseases of Calcium and Phosphate Metabolism, and Filière OSCAR, Paris, France.,INSERM U1185, Bicêtre Paris-Sud, Paris-Sud - Paris Saclay University, Le Kremlin-Bicêtre, France.,APHP, Platform of Expertise of Paris-Sud for Rare Diseases and Filière OSCAR, Bicêtre Paris-Sud Hospital (HUPS), Le Kremlin-Bicêtre, France.,APHP, Endocrinology and Diabetes for Children, Bicêtre Paris-Sud Hospital, Le Kremlin-Bicêtre, France
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10
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Rothenbuhler A, Schnabel D, Högler W, Linglart A. Diagnosis, treatment-monitoring and follow-up of children and adolescents with X-linked hypophosphatemia (XLH). Metabolism 2020; 103S:153892. [PMID: 30928313 DOI: 10.1016/j.metabol.2019.03.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 11/19/2022]
Abstract
Early diagnosis, optimal therapeutic management and regular follow up of children with X-linked hypophosphatemia (XLH) determine their long term outcomes and future quality of life. Biochemical screening of potentially affected newborns in familial cases and improving physician's knowledge on clinical signs, symptoms and biochemical characteristics of XLH for de novo cases should lead to earlier diagnosis and treatment initiation. The follow-up of children with XLH includes clinical, biochemical and radiological monitoring of treatment (efficacy and complications) and screening for XLH-related dental, neurosurgical, rheumatological, cardiovascular, renal and ENT complications. In 2018, the European Union approved the use of burosumab, a humanized monoclonal anti-FGF23 antibody, as an alternative therapy to conventional therapy (active vitamin D analogues and phosphate supplements) in growing children with XLH and insufficiently controlled disease. Diagnostic criteria of XLH and the principles of disease management with conventional treatment or with burosumab are reviewed in this paper.
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Affiliation(s)
- Anya Rothenbuhler
- APHP, Endocrinology and Diabetology for Children, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France; APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, filière OSCAR, Paris, France; APHP, Platform of Expertise for Rare Disorders Paris-Sud, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France.
| | - Dirk Schnabel
- Center for Chronic Sick Children, Pediatric Endocrinology, Charité, University Medicine Berlin, Germany
| | - Wolfgang Högler
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Department of Pediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Agnès Linglart
- APHP, Endocrinology and Diabetology for Children, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France; APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, filière OSCAR, Paris, France; APHP, Platform of Expertise for Rare Disorders Paris-Sud, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France
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11
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McKenna MJ, Martin-Grace J, Crowley R, Twomey PJ, Kilbane MT. Congenital hypophosphataemia in adults: determinants of bone turnover markers and amelioration of renal phosphate wasting following total parathyroidectomy. J Bone Miner Metab 2019; 37:685-693. [PMID: 30238432 DOI: 10.1007/s00774-018-0957-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 09/03/2018] [Indexed: 01/08/2023]
Abstract
Congenital hypophosphataemia (CH) is a collection of disorders that cause defective bone mineralisation manifesting with rickets in childhood and osteomalacia in adulthood. Bone turnover markers (BTMs) are surrogate measures of metabolic bone disease severity. We explored the utility of BTMs in 27 adults with CH: 23 had X-linked hypophosphataemia (XLH), of whom 2 were hypoparathyroid post-total parathyroidectomy (PTx); 2 had autosomal dominant hypophosphataemic rickets (ADHR), and 2 had none of the known mutations. We measured the renal tubular maximum reabsorption rate of phosphate (TmP/GFR), C-terminal fibroblast growth factor 23 (FGF23), parathyroid hormone (PTH), ionised calcium, 1,25-dihydroxyvitamin D [1,25(OH)2D], and a panel of BTMs: serum bone-specific alkaline phosphatase (bone ALP), osteocalcin (Oc), total procollagen type I amino-terminal propeptide (PINP), and carboxy-terminal telopeptide of type I collagen (CTX); and urine amino-terminal telopeptides of type I collagen (uNTX). After excluding 2 patients with XLH and PTx, the frequency of abnormal elevation in BTMs was: bone ALP (96%); CTX (72%); PINP (52%); uNTX (48%); Oc (28%). The strongest association with bone ALP was TmP/GFR. Those patients receiving phosphate supplements and alfacalcidol had significant elevation in CTX. The 2 patients with XLH and PTx had normalisation of TmP/GFR and near normalisation of BTMs post-operatively, despite marked elevation in both C-terminal and intact FGF23. In conclusion, BTMs in our CH patients indicated that most have abnormalities consistent with osteomalacia and many have mild secondary hyperparathyroidism; and the normalisation of TmP/GFR after total PTx in 2 cases of XLH remains unexplained, but possible causes are speculated.
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Affiliation(s)
- Malachi J McKenna
- Department of Endocrinology, St. Vincent's University Hospital, Elm Park, Dublin 4, D04T6F4, Ireland.
- UCD School of Medicine and Medical Science, University College Dublin, Dublin, Ireland.
| | - Julie Martin-Grace
- Department of Endocrinology, St. Vincent's University Hospital, Elm Park, Dublin 4, D04T6F4, Ireland
| | - Rachel Crowley
- Department of Endocrinology, St. Vincent's University Hospital, Elm Park, Dublin 4, D04T6F4, Ireland
- UCD School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Patrick J Twomey
- UCD School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
- Department of Clinical Chemistry, St. Vincent's University Hospital, Dublin, Ireland
| | - Mark T Kilbane
- UCD School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
- Department of Clinical Chemistry, St. Vincent's University Hospital, Dublin, Ireland
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12
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Imel EA, Glorieux FH, Whyte MP, Munns CF, Ward LM, Nilsson O, Simmons JH, Padidela R, Namba N, Cheong HI, Pitukcheewanont P, Sochett E, Högler W, Muroya K, Tanaka H, Gottesman GS, Biggin A, Perwad F, Mao M, Chen CY, Skrinar A, San Martin J, Portale AA. Burosumab versus conventional therapy in children with X-linked hypophosphataemia: a randomised, active-controlled, open-label, phase 3 trial. Lancet 2019; 393:2416-2427. [PMID: 31104833 PMCID: PMC7179969 DOI: 10.1016/s0140-6736(19)30654-3] [Citation(s) in RCA: 191] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 02/24/2019] [Accepted: 03/06/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND X-linked hypophosphataemia in children is characterised by elevated serum concentrations of fibroblast growth factor 23 (FGF23), hypophosphataemia, rickets, lower extremity bowing, and growth impairment. We compared the efficacy and safety of continuing conventional therapy, consisting of oral phosphate and active vitamin D, versus switching to burosumab, a fully human monoclonal antibody against FGF23, in paediatric X-linked hypophosphataemia. METHODS In this randomised, active-controlled, open-label, phase 3 trial at 16 clinical sites, we enrolled children with X-linked hypophosphataemia aged 1-12 years. Key eligibility criteria were a total Thacher rickets severity score of at least 2·0, fasting serum phosphorus lower than 0·97 mmol/L (3·0 mg/dL), confirmed PHEX (phosphate-regulating endopeptidase homolog, X-linked) mutation or variant of unknown significance in the patient or a family member with appropriate X-linked dominant inheritance, and receipt of conventional therapy for at least 6 consecutive months for children younger than 3 years or at least 12 consecutive months for children older than 3 years. Eligible patients were randomly assigned (1:1) to receive either subcutaneous burosumab starting at 0·8 mg/kg every 2 weeks (burosumab group) or conventional therapy prescribed by investigators (conventional therapy group). Both interventions lasted 64 weeks. The primary endpoint was change in rickets severity at week 40, assessed by the Radiographic Global Impression of Change global score. All patients who received at least one dose of treatment were included in the primary and safety analyses. The trial is registered with ClinicalTrials.gov, number NCT02915705. FINDINGS Recruitment took place between Aug 3, 2016, and May 8, 2017. Of 122 patients assessed, 61 were enrolled. Of these, 32 (18 girls, 14 boys) were randomly assigned to continue receiving conventional therapy and 29 (16 girls, 13 boys) to receive burosumab. For the primary endpoint at week 40, patients in the burosumab group had significantly greater improvement in Radiographic Global Impression of Change global score than did patients in the conventional therapy group (least squares mean +1·9 [SE 0·1] with burosumab vs +0·8 [0·1] with conventional therapy; difference 1·1, 95% CI 0·8-1·5; p<0·0001). Treatment-emergent adverse events considered possibly, probably, or definitely related to treatment by the investigator occurred more frequently with burosumab (17 [59%] of 29 patients in the burosumab group vs seven [22%] of 32 patients in the conventional therapy group). Three serious adverse events occurred in each group, all considered unrelated to treatment and resolved. INTERPRETATION Significantly greater clinical improvements were shown in rickets severity, growth, and biochemistries among children with X-linked hypophosphataemia treated with burosumab compared with those continuing conventional therapy. FUNDING Ultragenyx Pharmaceutical and Kyowa Kirin International.
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Affiliation(s)
- Erik A Imel
- Department of Medicine and Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Francis H Glorieux
- Shriners Hospital for Children - Canada, McGill University, Montreal, QC, Canada
| | - Michael P Whyte
- Shriners Hospitals for Children - St Louis, St Louis, MO, USA
| | - Craig F Munns
- The University of Sydney Children's Hospital Westmead Clinical School, The Children's Hospital at Westmead, Westmead, NSW, Australia; Department of Endocrinology, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Leanne M Ward
- Department of Pediatrics, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Ola Nilsson
- Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; School of Medical Sciences, Örebro University, Örebro, Sweden
| | - Jill H Simmons
- Department of Pediatrics, Division of Endocrinology and Diabetes, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - Raja Padidela
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Manchester, UK
| | - Noriyuki Namba
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization, Osaka, Japan; Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hae Il Cheong
- Seoul National University Children's Hospital, Seoul, Korea
| | - Pisit Pitukcheewanont
- Center of Endocrinology, Diabetes and Metabolism, Children's Hospital of Los Angeles, Los Angeles, CA, USA
| | - Etienne Sochett
- Department of Pediatrics, Hospital for Sick Children, Toronto, ON, Canada
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria; Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - Koji Muroya
- Kanagawa Children's Medical Center, Yokohama, Japan
| | - Hiroyuki Tanaka
- Okayama Saiseikai General Hospital Outpatient Center, Okayama, Japan
| | | | - Andrew Biggin
- The University of Sydney Children's Hospital Westmead Clinical School, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Farzana Perwad
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Meng Mao
- Ultragenyx Pharmaceutical, Novato, CA, USA
| | | | | | | | - Anthony A Portale
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
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13
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Abstract
Mineralized "hard" tissues of the skeleton possess unique biomechanical properties to support the body weight and movement and act as a source of essential minerals required for critical body functions. For a long time, extracellular matrix (ECM) mineralization in the vertebrate skeleton was considered as a passive process. However, the explosion of genetic studies during the past decades has established that this process is essentially controlled by multiple genetic pathways. These pathways regulate the homeostasis of ionic calcium and inorganic phosphate-two mineral components required for bone mineral formation, the synthesis of mineral scaffolding ECM, and the maintainence of the levels of the inhibitory organic and inorganic molecules controlling the process of mineral crystal formation and its growth. More recently, intracellular enzyme regulators of skeletal tissue mineralization have been identified. The current review will discuss the key determinants of ECM mineralization in bone and propose a unified model explaining this process.
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Affiliation(s)
- Monzur Murshed
- Faculty of Dentistry, McGill University, Montreal, Quebec H3A 1G1, Canada
- Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
- Shriners Hospital for Children, Montreal, Quebec H4A 0A9, Canada
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14
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Cheong HI, Yoo HW, Adachi M, Tanaka H, Fujiwara I, Hasegawa Y, Harada D, Sugimoto M, Okada Y, Kato M, Shimazaki R, Ozono K, Seino Y. First-in-Asian Phase I Study of the Anti-Fibroblast Growth Factor 23 Monoclonal Antibody, Burosumab: Safety and Pharmacodynamics in Adults With X-linked Hypophosphatemia. JBMR Plus 2018; 3:e10074. [PMID: 30828689 PMCID: PMC6383703 DOI: 10.1002/jbm4.10074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/03/2018] [Accepted: 08/05/2018] [Indexed: 12/26/2022] Open
Abstract
X‐linked hypophosphatemia (XLH) is a disease caused by abnormally elevated FGF23 levels, which cause persistent hypophosphatemia accompanied by subsequent reduction in bone mineralization that presents as rickets or osteomalacia. Burosumab is a fully human monoclonal antibody targeting FGF23 that is under development for the treatment of FGF23‐related hypophosphatemia including XLH. The safety, tolerability, and proof of concept of burosumab have been evaluated in patients with XLH in previous studies conducted in countries outside of Asia. The objective of this study was to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and expression of anti‐drug antibodies in Japanese and Korean adults with XLH. This was a multicenter, sequential dose‐escalation, open‐label, single‐dose study. This study began with cohort 1 (s.c. dose of burosumab 0.3 mg/kg), after which the dose was escalated sequentially in cohort 2 (s.c. dose of burosumab 0.6 mg/kg) and cohort 3 (s.c. dose of burosumab 1.0 mg/kg). The PK of burosumab were linear within the dose range of 0.3 to 1.0 mg/kg. The PD effects such as serum phosphorus concentration, serum 1,25[OH]2D3 concentration, and ratio of tubular maximum reabsorption rate of phosphate to glomerular filtration rate (TmP/GFR) were elevated after a single s.c. administration. The area under the receiver‐operating characteristic curve from 0 to t (AUC0–t) values calculated using the change from baseline values of serum phosphorus, serum 1,25(OH)2D3, and TmP/GFR were correlated with the AUC0–t of burosumab. Furthermore, no serious adverse events (AEs), deaths, remarkable increase or decrease in the corrected calcium or intact PTH levels, or signs of nephrocalcinosis or its worsening were observed after treatment. Some AEs and drug‐related AEs were observed; however, there were no clinically meaningful tendencies. The positive effects and acceptable safety profile seen in this study are encouraging for Japanese and Korean patients with XLH. © 2018 The Authors JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Hae Il Cheong
- Department of Pediatrics Seoul National University Children's Hospital Seoul Republic of Korea
| | - Han-Wook Yoo
- Department of Pediatrics Asan Medical Center Seoul Republic of Korea
| | - Masanori Adachi
- Department of Endocrinology and Metabolism Kanagawa Children's Medical Center Kanagawa Japan
| | - Hiroyuki Tanaka
- Department of Pediatrics Okayama Saiseikai General Hospital Okayama Japan
| | - Ikuma Fujiwara
- Department of Pediatric Endocrinology and Environmental Medicine Tohoku University Graduate School of Medicine Miyagi Japan
| | - Yukihiro Hasegawa
- Division of Endocrinology and Metabolism Tokyo Metropolitan Children's Medical Center Tokyo Japan
| | - Daisuke Harada
- Department of Pediatrics Osaka Hospital Japan Community Healthcare Organization (JCHO) Osaka Japan
| | | | | | | | | | - Keiichi Ozono
- Department of Pediatrics Osaka University Graduate School of Medicine Osaka Japan
| | - Yoshiki Seino
- Department of Pediatrics Osaka Hospital Japan Community Healthcare Organization (JCHO) Osaka Japan
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15
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Shanbhogue VV, Hansen S, Jørgensen NR, Beck-Nielsen SS. Impact of Conventional Medical Therapy on Bone Mineral Density and Bone Turnover in Adult Patients with X-Linked Hypophosphatemia: A 6-Year Prospective Cohort Study. Calcif Tissue Int 2018; 102:321-328. [PMID: 29143140 DOI: 10.1007/s00223-017-0363-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/09/2017] [Indexed: 12/24/2022]
Abstract
X-linked hypophosphatemia (XLH) is a rare, inheritable disorder manifesting as rickets in children and osteomalacia in adults. While conventional medical treatment with oral phosphate and alfacalcidol is recommended in childhood, it is undecided whether adults should continue therapy. The aim of this 6-year prospective study was to determine the impact of conventional medical treatment on areal bone mineral density (aBMD), bone turnover markers (BTMs) and measures of calcium homeostasis in 27 adult patients with XLH, 11 of whom received medical treatment. Lumbar spine and total hip aBMD, as assessed by DXA, and biochemical measures of calcium, phosphate, PTH, 1,25 dihydroxyvitamin D2+3 (1,25(OH)2D), fibroblast growth factor 23 (FGF23), P1NP and CTX were measured at baseline and at follow-up. The renal tubular reabsorption of PO4 (TmPO4/GFR) was calculated at both time points. Multilevel mixed-effects linear regression models were used for analyses. During the study period, spine and hip aBMD did not change significantly between treated and non-treated XLH patients. There was a trend towards a decrease in calcium, phosphate and TmPO4/GFR in the treatment group (p = 0.057, p = 0.080 and p = 0.063, respectively), whereas PTH, FGF23, 1,25(OH)2D and P1NP did not change significantly in either groups. However, CTX increased significantly in the treated compared to non-treated group (p = 0.044). Continuing conventional medical therapy in adulthood, although associated with increased bone resorption, does not promote or prevent loss of bone mass as evidenced from the stable aBMD of the hip and spine in XLH patients.
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Affiliation(s)
- Vikram Vinod Shanbhogue
- Department of Endocrinology, Odense University Hospital, Odense, Denmark
- Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Stinus Hansen
- Department of Endocrinology, Odense University Hospital, Odense, Denmark
- Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Niklas Rye Jørgensen
- Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark
- OPEN, Odense Patient data Explorative Network, Odense University Hospital/Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Signe Sparre Beck-Nielsen
- Department of Pediatrics, Kolding Hospital at Lillebaelt Hospital, Sygehusvej 24, DK-6000, Kolding, Denmark.
- Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark.
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16
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Ruppe MD, Zhang X, Imel EA, Weber TJ, Klausner MA, Ito T, Vergeire M, Humphrey JS, Glorieux FH, Portale AA, Insogna K, Peacock M, Carpenter TO. Effect of four monthly doses of a human monoclonal anti-FGF23 antibody (KRN23) on quality of life in X-linked hypophosphatemia. Bone Rep 2016; 5:158-162. [PMID: 28326356 PMCID: PMC4926842 DOI: 10.1016/j.bonr.2016.05.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 04/15/2016] [Accepted: 05/11/2016] [Indexed: 12/11/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is characterized by lower extremity deformities that lead to bone and/or joint pain that result from decreased renal tubular reabsorption leading to hypophosphatemia caused by elevated levels of fibroblast growth factor 23 (FGF23). Objective Validate the use of SF-36v2 Health Survey (SF-36v2) and the Western Ontario and McMaster Osteoarthritis Index (WOMAC) to measure previously unstudied health-related quality of life (HRQoL) in XLH patients and determine the change in HRQoL before and after treatment with KRN23, a human monoclonal anti-FGF23 antibody. Methods Twenty-eight adult outpatients with XLH received up to four doses of KRN23 administered subcutaneously every 28 days. General HRQoL was measured with the SF-36v2 and condition-related HRQoL with the WOMAC at baseline and study endpoint as a secondary outcome of a Phase 1/2, open-label, multicenter, dose-escalation trial. Results Testing for scale discriminant validity and convergent-divergent validity supported the use of these scales in the assessment of HRQoL in XLH. Both instruments indicated impairment of physical function at baseline with all mean scores showing a trend to improved health at study endpoint compared to baseline. When corrected for multiple comparisons, the score for Role Limitations due to physical health on the SF-36v2 which measures the patient's perception of their own chronic functional impairments due to poor physical health remained significantly improved (P < 0.05), increasing to the mean score of US adults. For the WOMAC, Physical Functioning and Stiffness scores were significantly improved (P < 0.05). Conclusion KRN23 administration was associated with significantly improved patient perception of their Physical Functioning and Stiffness due to their disease. This study demonstrates that the SF-36v2 and WOMAC are valid tools for assessing HRQoL in XLH. Quality of life was assessed in 26 XLH patients before and after 4 months of treatment with KRN23. All mean scores showed a trend of improved health after 4 doses of KRN23 treatment. Role limitations due to physical health was significantly improved after multiplicity correction. Patient reported outcomes can provide valuable information in evaluating new treatments for XLH.
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Affiliation(s)
- Mary D Ruppe
- Department of Medicine, Houston Methodist Hospital, Houston, TX, USA
| | | | - Erik A Imel
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Thomas J Weber
- Duke Clinical Bone Laboratories, Duke University Medical Center, Durham, North Carolina, USA
| | | | - Takahiro Ito
- Kyowa Hakko Kirin Pharma Inc., Princeton, NJ, USA
| | | | | | | | - Anthony A Portale
- Department of Pediatrics, University of California San Francisco, CA, USA
| | - Karl Insogna
- Yale Center for X-Linked Hypophosphatemia, Yale University School of Medicine, New Haven, CT, USA
| | - Munro Peacock
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Thomas O Carpenter
- Yale Center for X-Linked Hypophosphatemia, Yale University School of Medicine, New Haven, CT, USA
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17
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Ovejero D, Gafni RI, Collins MT. 1,25-Dihydroxyvitamin D as Monotherapy for XLH: Back to the Future? J Bone Miner Res 2016; 31:925-8. [PMID: 27093323 DOI: 10.1002/jbmr.2858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 04/08/2016] [Accepted: 04/14/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Diana Ovejero
- Section on Skeletal Disorders and Mineral Homeostasis, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Rachel I Gafni
- Section on Skeletal Disorders and Mineral Homeostasis, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Michael T Collins
- Section on Skeletal Disorders and Mineral Homeostasis, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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18
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Abstract
Overexpression of FGF23 results in hypophosphatemic rickets, which is characterized by renal phosphate wasting, inappropriately low circulating levels of the active form of vitamin D, and skeletal abnormalities. The precise mechanisms of how excess FGF23 leads to hypophosphatemic rickets are not clear. In this issue of the JCI, Bai and colleagues demonstrate that deletion or inhibition of CYP24A1, which initiates degradation of the active form of vitamin D, ameliorates skeletal abnormalities in two mouse models of hypophosphatemic rickets. While this work supports an important role for excess CYP24A1 activity in the pathogenesis of FGF23-mediated hypophosphatemic rickets, more work will need to be done before CYP24A1 inhibition can be integrated into the management of patients living with these diseases.
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19
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Zhang X, Peyret T, Gosselin NH, Marier JF, Imel EA, Carpenter TO. Population pharmacokinetic and pharmacodynamic analyses from a 4‐month intradose escalation and its subsequent 12‐month dose titration studies for a human monoclonal anti‐FGF23 antibody (KRN23) in adults with X‐linked hypophosphatemia. J Clin Pharmacol 2015; 56:429-38. [DOI: 10.1002/jcph.611] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 08/03/2015] [Indexed: 01/06/2023]
Affiliation(s)
| | | | | | - J. F. Marier
- Pharsight‐A Certara™ CompanyMontrealQuebecCanada
| | - Erik A. Imel
- Indiana University School of MedicineIndianapolisINUSA
| | - Thomas O. Carpenter
- Yale Center for X‐Linked HypophosphatemiaYale University School of MedicineNew HavenCTUSA
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Connor J, Olear EA, Insogna KL, Katz L, Baker S, Kaur R, Simpson CA, Sterpka J, Dubrow R, Zhang JH, Carpenter TO. Conventional Therapy in Adults With X-Linked Hypophosphatemia: Effects on Enthesopathy and Dental Disease. J Clin Endocrinol Metab 2015; 100:3625-32. [PMID: 26176801 PMCID: PMC4596038 DOI: 10.1210/jc.2015-2199] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Treatment of X-linked hypophosphatemia (XLH) with active vitamin D metabolites and phosphate can partially correct skeletal deformities. It is unclear whether therapy influences the occurrence of two major long-term morbidities in XLH: enthesopathy and dental disease. OBJECTIVE The objective of the study was to investigate the relationship between treatment and enthesopathy and dental disease in adult XLH patients. DESIGN The study was designed as observational and cross-sectional. SETTING The study was conducted at an academic medical center's hospital research unit. PARTICIPANTS Fifty-two XLH patients aged 18 years or older at the time of the study participated in the study. INTERVENTIONS There were no interventions. MAIN OUTCOME MEASURES The number of enthesopathy sites identified by radiographic skeletal survey and dental disease severity (more than five or five or fewer dental abscesses), identified historically, were measured. METHODS Associations between proportion of adult life and total life with treatment and number of enthesopathy sites were assessed using multiple linear regression, whereas associations between these exposure variables and dental disease severity were assessed using multiple logistic regression. All models were adjusted for confounding factors. RESULTS Neither proportion of adult nor total life with treatment was a significant predictor of extent of enthesopathy. In contrast, both of these treatment variables were significant predictors of dental disease severity (multivariate-adjusted global P = .0080 and P = .0010, respectively). Participants treated 0% of adulthood were more likely to have severe dental disease than those treated 100% of adulthood (adjusted odds ratio 25 [95% confidence interval 1.2-520]). As the proportion of adult life with treatment increased, the odds of having severe dental disease decreased (multivariate-adjusted P for trend = .015). CONCLUSIONS Treatment in adulthood may not promote or prevent enthesopathy; however, it may be associated with a lower risk of experiencing severe dental disease.
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Affiliation(s)
- Jessica Connor
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Elizabeth A Olear
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Karl L Insogna
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Lee Katz
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Suher Baker
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Raghbir Kaur
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Christine A Simpson
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - John Sterpka
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Robert Dubrow
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Jane H Zhang
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
| | - Thomas O Carpenter
- Departments of Epidemiology and Public Health (J.C., R.D.), Medicine (K.L.I., C.A.S., J.S.), Pediatrics (E.A.O., T.O.C.), and Diagnostic Imaging (L.K.), Yale University School of Medicine, Yale-New Haven Hospital Dentistry Program (S.B., R.K.), New Haven, Connecticut 06520; and the Veterans Administration Cooperative Studies Program Coordinating Center, Veterans Affairs Connecticut Healthcare System (J.H.Z.), West Haven, Connecticut 06516
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Zhang X, Imel EA, Ruppe MD, Weber TJ, Klausner MA, Ito T, Vergeire M, Humphrey J, Glorieux FH, Portale AA, Insogna K, Carpenter TO, Peacock M. Pharmacokinetics and pharmacodynamics of a human monoclonal anti-FGF23 antibody (KRN23) in the first multiple ascending-dose trial treating adults with X-linked hypophosphatemia. J Clin Pharmacol 2015; 56:176-85. [PMID: 26073451 PMCID: PMC5042055 DOI: 10.1002/jcph.570] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 06/09/2015] [Indexed: 12/28/2022]
Abstract
In X-linked hypophosphatemia (XLH), serum fibroblast growth factor 23 (FGF23) is increased and results in reduced renal maximum threshold for phosphate reabsorption (TmP), reduced serum inorganic phosphorus (Pi), and inappropriately low normal serum 1,25 dihydroxyvitamin D (1,25[OH]2 D) concentration, with subsequent development of rickets or osteomalacia. KRN23 is a recombinant human IgG1 monoclonal antibody that binds to FGF23 and blocks its activity. Up to 4 doses of KRN23 were administered subcutaneously every 28 days to 28 adults with XLH. Mean ± standard deviation KRN23 doses administered were 0.05, 0.10 ± 0.01, 0.28 ± 0.06, and 0.48 ± 0.16 mg/kg. The mean time to reach maximum serum KRN23 levels was 7.0 to 8.5 days. The mean KRN23 half-life was 16.4 days. The mean area under the concentration-time curve (AUCn ) for each dosing interval increased proportionally with increases in KRN23 dose. The mean intersubject variability in AUCn ranged from 30% to 37%. The area under the effect concentration-time curve (AUECn ) for change from baseline in TmP per glomerular filtration rate, serum Pi, 1,25(OH)2 D, and bone markers for each dosing interval increased linearly with increases in KRN23 AUCn . Linear correlation between serum KRN23 concentrations and increase in serum Pi support KRN23 dose adjustments based on predose serum Pi concentration.
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Affiliation(s)
| | - Erik A Imel
- Indiana University School of Medicine, Indianapolis, IN, USA
| | | | | | | | - Takahiro Ito
- Kyowa Hakko Kirin Pharma Inc., Princeton, NJ, USA
| | | | | | | | | | - Karl Insogna
- Yale Center for X-Linked Hypophosphatemia, Yale University School of Medicine, New Haven, CT, USA
| | - Thomas O Carpenter
- Yale Center for X-Linked Hypophosphatemia, Yale University School of Medicine, New Haven, CT, USA
| | - Munro Peacock
- Indiana University School of Medicine, Indianapolis, IN, USA
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Imel EA, Zhang X, Ruppe MD, Weber TJ, Klausner MA, Ito T, Vergeire M, Humphrey JS, Glorieux FH, Portale AA, Insogna K, Peacock M, Carpenter TO. Prolonged Correction of Serum Phosphorus in Adults With X-Linked Hypophosphatemia Using Monthly Doses of KRN23. J Clin Endocrinol Metab 2015; 100:2565-73. [PMID: 25919461 PMCID: PMC4495171 DOI: 10.1210/jc.2015-1551] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
CONTEXT In X-linked hypophosphatemia (XLH), elevated fibroblast growth factor 23 (FGF23) decreases the renal tubular maximum reabsorption rate of phosphate/glomerular filtration rate (TmP/GFR) and serum inorganic phosphorus (Pi), resulting in rickets and/or osteomalacia. OBJECTIVE The objective was to test the hypothesis that monthly KRN23 (anti-FGF23 antibody) would safely improve serum Pi in adults with XLH. DESIGN Two sequential open-label phase 1/2 studies were done. SETTING Six academic medical centers were used. PARTICIPANTS Twenty-eight adults with XLH participated in a 4-month dose-escalation study (0.05-0.6 mg/kg); 22 entered a 12-month extension study (0.1-1 mg/kg). INTERVENTION KRN23 was injected sc every 28 days. MAIN OUTCOME MEASURE The main outcome measure was the proportion of subjects attaining normal serum Pi and safety. RESULTS At baseline, mean TmP/GFR, serum Pi, and 1,25-dihydroxyvitamin D [1,25(OH)2D] were 1.6 ± 0.4 mg/dL, 1.9 ± 0.3 mg/dL, and 36.6 ± 14.3 pg/mL, respectively. During dose escalation, TmP/GFR, Pi, and 1,25(OH)2D increased, peaking at 7 days for TmP/GFR and Pi and at 3-7 days for 1,25(OH)2D, remaining above (TmP/GFR, Pi) or near [1,25(OH)2D] pre-dose levels at trough. After each of the four escalating doses, peak Pi was between 2.5 and 4.5 mg/dL in 14.8, 37.0, 74.1, and 88.5% of subjects, respectively. During the 12-month extension, peak Pi was in the normal range for 57.9-85.0% of subjects, and ≥25% maintained trough Pi levels within the normal range. Serum Pi did not exceed 4.5 mg/dL in any subject. Although 1,25(OH)2D levels increased transiently, mean serum and urinary calcium remained normal. KRN23 treatment increased biomarkers of skeletal turnover and had a favorable safety profile. CONCLUSIONS Monthly KRN23 significantly increased serum Pi, TmP/GFR, and 1,25(OH)2D in all subjects. KRN23 has potential for effectively treating XLH.
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Affiliation(s)
- Erik A Imel
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Xiaoping Zhang
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Mary D Ruppe
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Thomas J Weber
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Mark A Klausner
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Takahiro Ito
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Maria Vergeire
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Jeffrey S Humphrey
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Francis H Glorieux
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Anthony A Portale
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Karl Insogna
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Munro Peacock
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
| | - Thomas O Carpenter
- Indiana University School of Medicine (E.A.I., M.P.), Indianapolis, Indiana 46202; Kyowa Hakko Kirin Pharma Inc (X.Z., M.A.K., T.I., M.V., J.S.H.), Princeton, New Jersey 08540; Houston Methodist Hospital (M.D.R.), Houston, Texas 77030; Duke University Medical Center (T.J.W.), Durham, North Carolina 27710; Shriners Hospital for Children (F.H.G.), Montreal, Quebec H3G 1A6, Canada; University of California (A.A.P.), San Francisco, California 94143; and Yale Center for X-Linked Hypophosphatemia (K.I., T.O.C.), Yale University School of Medicine, New Haven, Connecticut 06520
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Carpenter TO, Imel EA, Ruppe MD, Weber TJ, Klausner MA, Wooddell MM, Kawakami T, Ito T, Zhang X, Humphrey J, Insogna KL, Peacock M. Randomized trial of the anti-FGF23 antibody KRN23 in X-linked hypophosphatemia. J Clin Invest 2014; 124:1587-97. [PMID: 24569459 DOI: 10.1172/jci72829] [Citation(s) in RCA: 208] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 12/17/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND X-linked hypophosphatemia (XLH) is the most common heritable form of rickets and osteomalacia. XLH-associated mutations in phosphate-regulating endopeptidase (PHEX) result in elevated serum FGF23, decreased renal phosphate reabsorption, and low serum concentrations of phosphate (inorganic phosphorus, Pi) and 1,25-dihydroxyvitamin D [1,25(OH)2D]. KRN23 is a human anti-FGF23 antibody developed as a potential treatment for XLH. Here, we have assessed the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of KRN23 following a single i.v. or s.c. dose of KRN23 in adults with XLH. METHODS Thirty-eight XLH patients were randomized to receive a single dose of KRN23 (0.003-0.3 mg/kg i.v. or 0.1-1 mg/kg s.c.) or placebo. PK, PD, immunogenicity, safety, and tolerability were assessed for up to 50 days. RESULTS KRN23 significantly increased the maximum renal tubular threshold for phosphate reabsorption (TmP/GFR), serum Pi, and 1,25(OH)2D compared with that of placebo (P<0.01). The maximum serum Pi concentration occurred later following s.c. dosing (8-15 days) compared with that seen with i.v. dosing (0.5-4 days). The effect duration was dose related and persisted longer in patients who received s.c. administration. Changes from baseline in TmP/GFR, serum Pi, and serum 1,25(OH)2D correlated with serum KRN23 concentrations. The mean t1/2 of KRN23 was 8-12 days after i.v. administration and 13-19 days after s.c. administration. Patients did not exhibit increased nephrocalcinosis or develop hypercalciuria, hypercalcemia, anti-KRN23 antibodies, or elevated serum parathyroid hormone (PTH) or creatinine. CONCLUSION KRN23 increased TmP/GFR, serum Pi, and serum 1,25(OH)2D. The positive effect of KR23 on serum Pi and its favorable safety profile suggest utility for KRN23 in XLH patients. Trial registration. Clinicaltrials.gov NCT00830674. Funding. Kyowa Hakko Kirin Pharma, Inc.
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Linglart A, Biosse-Duplan M, Briot K, Chaussain C, Esterle L, Guillaume-Czitrom S, Kamenicky P, Nevoux J, Prié D, Rothenbuhler A, Wicart P, Harvengt P. Therapeutic management of hypophosphatemic rickets from infancy to adulthood. Endocr Connect 2014; 3:R13-30. [PMID: 24550322 PMCID: PMC3959730 DOI: 10.1530/ec-13-0103] [Citation(s) in RCA: 207] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In children, hypophosphatemic rickets (HR) is revealed by delayed walking, waddling gait, leg bowing, enlarged cartilages, bone pain, craniostenosis, spontaneous dental abscesses, and growth failure. If undiagnosed during childhood, patients with hypophosphatemia present with bone and/or joint pain, fractures, mineralization defects such as osteomalacia, entesopathy, severe dental anomalies, hearing loss, and fatigue. Healing rickets is the initial endpoint of treatment in children. Therapy aims at counteracting consequences of FGF23 excess, i.e. oral phosphorus supplementation with multiple daily intakes to compensate for renal phosphate wasting and active vitamin D analogs (alfacalcidol or calcitriol) to counter the 1,25-diOH-vitamin D deficiency. Corrective surgeries for residual leg bowing at the end of growth are occasionally performed. In absence of consensus regarding indications of the treatment in adults, it is generally accepted that medical treatment should be reinitiated (or maintained) in symptomatic patients to reduce pain, which may be due to bone microfractures and/or osteomalacia. In addition to the conventional treatment, optimal care of symptomatic patients requires pharmacological and non-pharmacological management of pain and joint stiffness, through appropriated rehabilitation. Much attention should be given to the dental and periodontal manifestations of HR. Besides vitamin D analogs and phosphate supplements that improve tooth mineralization, rigorous oral hygiene, active endodontic treatment of root abscesses and preventive protection of teeth surfaces are recommended. Current outcomes of this therapy are still not optimal, and therapies targeting the pathophysiology of the disease, i.e. FGF23 excess, are desirable. In this review, medical, dental, surgical, and contributions of various expertises to the treatment of HR are described, with an effort to highlight the importance of coordinated care.
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Affiliation(s)
- Agnès Linglart
- Service d'Endocrinologie et Diabétologie de l'EnfantHôpital Bicêtre, APHP78 rue du Général Leclerc , Le Kremlin Bicêtre, 94270France
- Université Paris 11 faculté de Médecine, Hôpital Bicêtre70 rue du général Leclerc, Le Kremlin-Bicêtre, 94270France
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du PhosphoreLe Kremlin-BicêtreFrance
- Correspondence should be addressed to A Linglart
| | - Martin Biosse-Duplan
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du PhosphoreLe Kremlin-BicêtreFrance
- Service d'Odontologie-Maladies Rares Hôpital Bretonneau 2 rue Carpeaux Paris, 75018France
- Université Paris Descartes 12 Rue de l'École de MédecineParis, 75006France
| | - Karine Briot
- Université Paris Descartes 12 Rue de l'École de MédecineParis, 75006France
- Service Rhumatologie B Hôpital Cochin, APHP27, rue du Faubourg Saint-Jacques, Paris, 75014France
| | - Catherine Chaussain
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du PhosphoreLe Kremlin-BicêtreFrance
- Service d'Odontologie-Maladies Rares Hôpital Bretonneau 2 rue Carpeaux Paris, 75018France
- Université Paris Descartes 12 Rue de l'École de MédecineParis, 75006France
| | - Laure Esterle
- Service d'Endocrinologie et Diabétologie de l'EnfantHôpital Bicêtre, APHP78 rue du Général Leclerc , Le Kremlin Bicêtre, 94270France
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du PhosphoreLe Kremlin-BicêtreFrance
| | - Séverine Guillaume-Czitrom
- Service de Pédiatrie générale – Consultation de rhumatologieHôpital Bicêtre, APHP78 rue du Général Leclerc , Le Kremlin Bicêtre, 94270France
- Centre de Référence des Maladies Rares des Maladies Auto-Inflammatoires Rares de l'EnfantLe Kremlin BicêtreFrance
| | - Peter Kamenicky
- Service d'Endocrinologie et des Maladies de la ReproductionHôpital Bicêtre, APHP78 rue du Général Leclerc , Le Kremlin Bicêtre, 94270France
- Université Paris 11 faculté de Médecine, Hôpital Bicêtre70 rue du général Leclerc, Le Kremlin-Bicêtre, 94270France
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du PhosphoreLe Kremlin-BicêtreFrance
| | - Jerome Nevoux
- Service d'ORL et chirurgie cervico-maxillo-facialeHôpital Bicêtre, APHP78 rue du Général Leclerc , Le Kremlin Bicêtre, 94270France
- Université Paris 11 faculté de Médecine, Hôpital Bicêtre70 rue du général Leclerc, Le Kremlin-Bicêtre, 94270France
| | - Dominique Prié
- Université Paris Descartes 12 Rue de l'École de MédecineParis, 75006France
- Service d'explorations fonctionnelles rénales, Hôpital Necker-Enfants Malades149 rue de Sèvres, Paris, 75015France
| | - Anya Rothenbuhler
- Service d'Endocrinologie et Diabétologie de l'EnfantHôpital Bicêtre, APHP78 rue du Général Leclerc , Le Kremlin Bicêtre, 94270France
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du PhosphoreLe Kremlin-BicêtreFrance
| | - Philippe Wicart
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du PhosphoreLe Kremlin-BicêtreFrance
- Université Paris Descartes 12 Rue de l'École de MédecineParis, 75006France
- Service de Chirurgie infantile orthopédiqueHôpital Necker-Enfants Malades149 rue de Sèvres, Paris, 75015 France
| | - Pol Harvengt
- Association de patients RVRH-XLH20 rue Merlin de Thionville, Suresnes , 92150France
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Growth in PHEX-associated X-linked hypophosphatemic rickets: the importance of early treatment. Pediatr Nephrol 2012; 27:581-8. [PMID: 22101457 DOI: 10.1007/s00467-011-2046-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/16/2011] [Accepted: 09/19/2011] [Indexed: 01/10/2023]
Abstract
Inactivating mutations in phosphate-regulating endopeptidase (PHEX) cause X-linked hypophosphatemic rickets (XLHR) characterized by phosphaturia, hypophosphatemia, bony deformities, and growth retardation. We assessed the efficacy of combined calcitriol and orally administered phosphate (Pi) therapy on longitudinal growth in relation to age at treatment onset in a retrospective, single-center review of children with XLHR and documented PHEX mutations. Growth was compared in those who started treatment before (G1; N = 10; six boys) and after (G2; N = 13; five boys) 1 year old. Median height standard deviation score (HSDS) at treatment onset was normal in G1: 0.1 [interquartile range (IR) -1.3 to 0.4) and significantly (p = 0.004) lower in G2 (IR -2.1 (-2.8 to -1.4). Treatment duration was similar [G1 8.5 (4.0-15.2) vs G2 11.9 (6.2-14.3) years; p = 0.56], as were prescribed phosphate and calcitriol doses. Recent HSDS was significantly (p = 0.009) better in G1 [-0.7 (-1.5 to 0.3)] vs G2 [-2.0 (-2.3 to -1.0)]. No effects of gender or genotype on growth could be identified. Children with PHEX-associated XLHR benefit from early treatment and can achieve normal growth. Minimal catchup growth was seen in those who started treatment later. Our findings emphasize the importance of early diagnosis to allow treatment before growth has been compromised.
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Carpenter TO, Imel EA, Holm IA, Jan de Beur SM, Insogna KL. A clinician's guide to X-linked hypophosphatemia. J Bone Miner Res 2011; 26:1381-8. [PMID: 21538511 PMCID: PMC3157040 DOI: 10.1002/jbmr.340] [Citation(s) in RCA: 382] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 12/28/2010] [Accepted: 01/13/2011] [Indexed: 11/10/2022]
Abstract
X-linked hypophosphatemia (XLH) is the prototypic disorder of renal phosphate wasting, and the most common form of heritable rickets. Physicians, patients, and support groups have all expressed concerns about the dearth of information about this disease and the lack of treatment guidelines, which frequently lead to missed diagnoses or mismanagement. This perspective addresses the recommendation by conferees for the dissemination of concise and accessible treatment guidelines for clinicians arising from the Advances in Rare Bone Diseases Scientific Conference held at the NIH in October 2008. We briefly review the clinical and pathophysiologic features of the disorder and offer this guide in response to the conference recommendation, based on our collective accumulated experience in the management of this complex disorder.
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Affiliation(s)
| | - Erik A. Imel
- Indiana University School of Medicine, Indianapolis IN
| | - Ingrid A. Holm
- Division of Genetics, Program in Genomics, and the Manton Center for Orphan Disease Research, Children's Hospital Boston and Harvard Medical School, Boston, MA
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Meir T, Levi R, Lieben L, Libutti S, Carmeliet G, Bouillon R, Silver J, Naveh-Many T. Deletion of the vitamin D receptor specifically in the parathyroid demonstrates a limited role for the receptor in parathyroid physiology. Am J Physiol Renal Physiol 2009; 297:F1192-8. [DOI: 10.1152/ajprenal.00360.2009] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
1,25(OH)2D3 decreases parathyroid hormone (PTH) gene transcription through the vitamin D receptor (VDR). Total body VDR−/− mice have high PTH levels, hypocalcemia, hypophosphatemia, and bone malformations. To investigate PTH regulation by the VDR specifically in the parathyroid, we generated parathyroid-specific VDR knockout mice ( PT-VDR−/−). In both strains, there was a decrease in parathyroid calcium receptor (CaR) levels. The number of proliferating parathyroid cells was increased in the VDR−/− mice but not in the PT-VDR−/− mice. Serum PTH levels were moderately but significantly increased in the PT-VDR−/− mice with normal serum calcium levels. The sensitivity of the parathyroid glands of the PT-VDR−/− mice to calcium was intact as measured by serum PTH levels after changes in serum calcium. This indicates that the reduced CaR in the PT-VDR−/− mice enables a physiologic response to serum calcium. Serum C-terminal collagen crosslinks, a marker of bone resorption, were increased in the PT-VDR−/− mice with no change in the bone formation marker, serum osteocalcin, consistent with a resorptive effect due to the increased serum PTH levels in the PT-VDR−/− mice. Therefore, deletion of the VDR specifically in the parathyroid decreases parathyroid CaR expression and only moderately increases basal PTH levels, suggesting that the VDR has a limited role in parathyroid physiology.
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Affiliation(s)
- Tomer Meir
- Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hospital, Jerusalem, Israel
| | - Ronen Levi
- Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hospital, Jerusalem, Israel
| | - Liesbet Lieben
- Laboratory of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium
| | | | - Geert Carmeliet
- Laboratory of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Roger Bouillon
- Laboratory of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Justin Silver
- Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hospital, Jerusalem, Israel
| | - Tally Naveh-Many
- Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hospital, Jerusalem, Israel
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Petje G, Meizer R, Radler C, Aigner N, Grill F. Deformity correction in children with hereditary hypophosphatemic rickets. Clin Orthop Relat Res 2008; 466:3078-85. [PMID: 18841431 PMCID: PMC2628230 DOI: 10.1007/s11999-008-0547-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 09/15/2008] [Indexed: 01/31/2023]
Abstract
UNLABELLED X-linked hereditary hypophosphatemic rickets can induce various multiplanar deformities of the lower limb. We evaluated our ability to correct these deformities and assessed complications and recurrence rates in 10 children (eight girls and a pair of twin boys) followed from early childhood to skeletal maturity. We performed 37 corrective operations in 10 children. Depending on the patient's age, external fixation was used in 53 segments: Kirschner wires in 18, DynaFix in three, the Taylor Spatial Frame device in 13, and the Ilizarov device in 19. Internal fixation with intramedullary nailing was performed in 12. After bone consolidation, we radiographically determined the mechanical axis at an average distance of 0.5 cm medial to the center of the knee. The average mechanical lateral distal femoral angle was 85 degrees (range, 83 degrees-92 degrees) and the average mechanical medial proximal tibial angle was 91 degrees (range, 85 degrees-92 degrees). Deviation of the mechanical axis and knee orientation lines was increased at the followups conducted during a period of 5 to 12 months. Additional followups revealed a recurrence rate of 90% after the first corrective procedure and 60% after a second procedure. LEVEL OF EVIDENCE Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
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Affiliation(s)
- Gert Petje
- Department of Pediatric Orthopedics, Orthopedic Hospital Vienna-Speising, Speisinger Strasse 109, 1130 Vienna, Austria
| | - Roland Meizer
- Department of Pediatric Orthopedics, Orthopedic Hospital Vienna-Speising, Speisinger Strasse 109, 1130 Vienna, Austria
| | - Christof Radler
- Department of Pediatric Orthopedics, Orthopedic Hospital Vienna-Speising, Speisinger Strasse 109, 1130 Vienna, Austria
| | - Nicolas Aigner
- Department of Pediatric Orthopedics, Orthopedic Hospital Vienna-Speising, Speisinger Strasse 109, 1130 Vienna, Austria
| | - Franz Grill
- Department of Pediatric Orthopedics, Orthopedic Hospital Vienna-Speising, Speisinger Strasse 109, 1130 Vienna, Austria
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Imel EA, Hui SL, Econs MJ. FGF23 concentrations vary with disease status in autosomal dominant hypophosphatemic rickets. J Bone Miner Res 2007; 22:520-6. [PMID: 17227222 DOI: 10.1359/jbmr.070107] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
UNLABELLED We measured FGF23 concentrations in subjects with ADHR. FGF23 and serum phosphate correlated positively in controls and negatively in subjects with ADHR. Elevated FGF23 concentrations were associated with lower phosphate values. The variable phenotype in ADHR may be caused by fluctuations in FGF23. INTRODUCTION Autosomal dominant hypophosphatemic rickets (ADHR) is a rare disorder of phosphaturia, hypophosphatemia, inappropriately low/normal calcitriol, and rickets/osteomalacia. ADHR is caused by mutations in a circulating peptide, fibroblast growth factor 23 (FGF23). We present the first report of FGF23 concentrations in subjects with ADHR. The aim was to test the hypotheses that subjects with ADHR have elevated FGF23 concentrations and that FGF23 concentrations are associated with disease severity. MATERIALS AND METHODS This was an observational study at a tertiary referral center. Subjects were from three kindreds with FGF23 mutations causing ADHR (n = 42). Controls were participants from these families without mutations (n = 55). Fasting blood and urine samples were obtained. Biochemistries were determined, and FGF23 concentrations were measured using two ELISAs. RESULTS Three cases are presented illustrating activity of disease and FGF23 concentrations. One case shows persistent hypophosphatemia and elevation of FGF23 concentrations, whereas another shows remission of hypophosphatemia corresponding to a decrease in previously elevated FGF23 concentrations. Overall cross-sectional group differences were nonsignificant for serum phosphate and FGF23 concentrations. C-terminal FGF23 concentration in controls was 61.0 +/- 28.6 (SD) RU/ml (median, 52.5 RU/ml), and in subjects with mutations was 148.8 +/- 374.5 RU/ml (median, 63.1 RU/ml). Mean intact FGF23 concentration in controls was 44.7 +/- 14.9 pg/ml (median, 40.4 pg/ml), and in subjects with mutations was 83.2 +/- 233.0 pg/ml (median, 39.0 pg/ml). C-terminal FGF23 concentrations were at least +2 SD in 10/42(24%), and intact FGF23 concentrations were at least +2 SD in 3/34(9%). Phosphate correlated positively with C-terminal and intact FGF23 in both controls and in subjects with mutations with phosphate >2.5 mg/dl but correlated significantly negatively with C-terminal and intact FGF23 in ADHR subjects with phosphate < or =2.5 mg/dl. CONCLUSIONS Elevated FGF23 concentrations are associated with hypophosphatemia in ADHR, and remission of the phenotype is associated with lower FGF23 concentrations. FGF23 has an opposite relationship with phosphate in ADHR compared with controls. We conclude that ADHR symptoms and disease severity likely fluctuate with FGF23 concentrations.
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Affiliation(s)
- Erik A Imel
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
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Rauch F, Middelmann B, Cagnoli M, Keller KM, Schönau E. Comparison of total alkaline phosphatase and three assays for bone-specific alkaline phosphatase in childhood and adolescence. Acta Paediatr 1997; 86:583-7. [PMID: 9202791 DOI: 10.1111/j.1651-2227.1997.tb08938.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We compared serum levels of total alkaline phosphatase (TAP) and bone-specific alkaline phosphatase (BAP) as determined by three different assays (lectin affinity electrophoresis, immunoradiometric assay, enzyme-linked immunosorbent assay) in subjects aged 5-20 years suffering from X-linked hypophosphatemic rickets (n = 14), chronic renal failure (n = 10) and chronic cholestatic liver disease (n = 16). Results were compared to controls of the same age and were expressed as standard deviation scores (SDS). TAP correlated significantly with BAP (r > 0.9 for each assay; p < 0.001) in controls. In children with cholestatic diseases, TAP (median SDS + 2.0) was elevated, but BAP, as measured by the electrophoretic assay, was within the reference range for most patients (median SDS: -0.4; p = 0.003 for the difference between the median SDS of TAP and BAP). In contrast, results for BAP as determined by the two immunoassays were not significantly different from TAP in any of the three patient groups (p > 0.05 in each group for both assays). In this study, the two immunoassays did not have a detectable advantage over lectin affinity electrophoresis in the determination of BAP.
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Affiliation(s)
- F Rauch
- Kinderklinik, Universität zu Köln, Germany
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31
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van den Bos T, Oosting J, Everts V, Beertsen W. Mineralization of alkaline phosphatase-complexed collagen implants in the rat in relation to serum inorganic phosphate. J Bone Miner Res 1995; 10:616-24. [PMID: 7610933 DOI: 10.1002/jbmr.5650100415] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The present study was designed to determine the relationship between mineralization of collagenous matrices and serum levels of calcium and inorganic phosphate. Collagen slices were prepared from bovine dentin or cortical bone and complexed with varying amounts of intestinal alkaline phosphatase (ALP). The enzyme was added to induce de novo mineralization. The ALP-complexed slices were implanted subcutaneously over the skull and in the dorsolateral aspect of the abdominal wall in female Wistar rats of various ages (5-, 10-, 20-, or 35-week-old) and in young male rats fed on a low-P diet. After 1-4 weeks, the implants were removed and analyzed for calcium and phosphate content. In addition, serum levels of calcium and phosphate (total and inorganic) were determined. It was shown that the highest mineral influx occurred in the younger rats (which were also highest in serum P(i)), whereas almost no mineral uptake occurred in the older ones. Also in rats fed on a low-P diet (which were low in serum P(i), a strongly decreased mineral influx was noted. In all animal groups a positive correlation was found between the degree of mineralization and serum P(i). No distinct relationship was found between serum Ca/organic phosphate levels and mineral influx in the implants. In vitro incubation of ALP-collagen conjugates in serum from younger and older rats confirmed our view that serum P(i), besides local levels of ALP, is important in de novo mineral deposition. For accretion of mineral in partially remineralized collagenous carriers, ALP activity was not required.
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Affiliation(s)
- T van den Bos
- Department of Periodontology, Academic Center for Dentistry Amsterdam (ACTA), The Netherlands
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Taylor A, Sherman NH, Norman ME. Nephrocalcinosis in X-linked hypophosphatemia: effect of treatment versus disease. Pediatr Nephrol 1995; 9:173-5. [PMID: 7794712 DOI: 10.1007/bf00860736] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
While the literature has suggested that vitamin D and phosphate therapy benefits children, and possibly adults, with X-linked hypophosphatemia (XLH), there have been increasing reports of nephrocalcinosis by renal ultrasound examination in treated patients. Although it has been assumed that nephrocalcinosis is the result of treatment, there has been no systematic comparison of treated and untreated XLH patients with long-term follow-up. Therefore, we studied 10 adults and 4 children by renal ultrasound examination with no history of medical therapy and 10 adults and 8 children with a history of medical therapy. None of the untreated patients had nephrocalcinosis; 5 treated adults and 5 treated children had nephrocalcinosis. In 3 of 4 treated children, serial renal ultrasounds did not show progression of the nephrocalcinosis. One patient progressed from baseline to year 1 only. Comparisons of means between treated patients without and with nephrocalcinosis showed statistically significant differences for urine calcium/creatinine ratios and urine phosphorus/creatinine ratios, differences not seen between untreated patients and treated patients without nephrocalcinosis. Phosphate dose, but not vitamin D dose, was statistically significantly different between the two treated groups. Our studies point to a convincing role for the association between nephrocalcinosis, as diagnosed by renal ultrasound examination, and medical therapy.
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Affiliation(s)
- A Taylor
- Department of Clinical Research, Alfred I. duPont Institute, Wilmington, DE 19899, USA
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Nakajima S, Yamaoka K, Okada S, Pike JW, Seino Y, Haussler MR. 1,25-Dihydroxyvitamin D3 does not up-regulate vitamin D receptor messenger ribonucleic acid levels in hypophosphatemic mice. BONE AND MINERAL 1992; 19:201-13. [PMID: 1335319 DOI: 10.1016/0169-6009(92)90870-j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) administration on duodenal vitamin D receptor (VDR) mRNA levels in hypophosphatemic (Hyp) mice, a murine homologue of human X-linked hypophosphatemic rickets, was examined. Basal levels of VDR mRNA in Hyp mice were similar to those of normal littermates and, in normal mice, VDR mRNA levels were up-regulated 1.8-2.7-fold after injection of 1 microgram/kg 1,25(OH)2D3. In contrast, no significant change in VDR mRNA was observed in Hyp mice treated with 1,25(OH)2D3. To determine the effect of phosphate repletion on VDR mRNA levels, high-phosphate diet was fed to Hyp mice. Although plasma phosphorus concentration was restored to normal, up-regulation of VDR mRNA was not recovered with phosphate supplementation. These results indicate that the vitamin D-resistance in Hyp mice is not caused by hypophosphatemia, per se, and may result from a fundamental molecular defect in vitamin D action at the intestine which could be related to ineffective up-regulation of VDR mRNA by 1,25(OH)2D3.
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Affiliation(s)
- S Nakajima
- Department of Pediatrics, Osaka University School of Medicine, Japan
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34
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Scriver CR, Tenenhouse HS. Mendelian Phenotypes as “Probes” of Renal Transport Systems for Amino Acids and Phosphate. Compr Physiol 1992. [DOI: 10.1002/cphy.cp080242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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35
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Brown EM. Kidney and Bone: Physiological and Pathophysiological Relationships. Compr Physiol 1992. [DOI: 10.1002/cphy.cp080239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Petersen DJ, Boniface AM, Schranck FW, Rupich RC, Whyte MP. X-linked hypophosphatemic rickets: a study (with literature review) of linear growth response to calcitriol and phosphate therapy. J Bone Miner Res 1992; 7:583-97. [PMID: 1414477 DOI: 10.1002/jbmr.5650070602] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Not all children with X-linked hypophosphatemia (XLH) have demonstrated improved linear growth with calcitriol [1,25-(OH)2D3] and inorganic phosphate (Pi) therapy. To assess which factors are associated with a favorable growth response during this treatment, we retrospectively compared demographics and biochemical parameters of bone metabolism to the linear growth patterns of 20 children with XLH who were prepubertal and had not required osteotomy. A total of 15 patients had family histories consistent with XLH; 5 appeared to be sporadic cases. During 3 years of therapy, the growth velocities of 12 patients had been at or above the mean for age (good growers) and those of 8 patients had been below the mean (poor growers). Data from the two groups were contrasted. We found no difference between the good growers and poor growers before or after the 3 year period of therapy in mean age, dietary calcium, calcitriol dose or compliance, or Pi dose or compliance. Both groups increased their mean fasting serum Pi levels with treatment. The TmP/GFR (mean +/- SEM) of the good growers improved with therapy (1.9 +/- 0.2 to 2.6 +/- 0.2 mg/dl, p = 0.01), and their posttreatment value was higher compared to that of the poor growers (2.6 +/- 0.1 versus 2.2 +/- 0.1 mg/dl, p = 0.02). However, their enhanced TmP/GFR was not associated with a reduction in serum iPTH levels (before, 693 +/- 50; after, 688 +/- 76 pg/ml; p = 0.9). The Z test for binomial proportions showed that the group that grew well contained a disproportionate number of girls (10 of 12, p = 0.04). Our findings suggest that calcitriol may exert a direct effect on the renal tubule to improve Pi reclamation in XLH. The observation that heterozygous girls appear to respond better than hemizygous boys to calcitriol and Pi therapy provides evidence for a gene dosage effect in the expression of this X-linked dominant disorder.
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Affiliation(s)
- D J Petersen
- Metabolic Research Unit, Shriners Hospital for Crippled Children, St. Louis, Missouri
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37
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Tenenhouse HS, Scriver CR. X-linked hypophosphatemia. A phenotype in search of a cause. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1992; 24:685-91. [PMID: 1592145 DOI: 10.1016/0020-711x(92)90001-h] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
XLH is an important disease, it is the subject of several classic articles in the medical sciences (Scriver et al., 1991), and it has been an important stimulus to study renal hypophosphatemias and how they are involved in rickets and osteomalacia (Scriver, 1974; Scriver and Tenenhouse, 1991). Renal transport is the major determinant of phosphate homeostasis in mammals and it is unlikely that this important biochemical parameter would have been left by evolution to a single renal transport system. Together physiologists and geneticists found that the mammalian kidney has several gene products dedicated to phosphate transport. That has implications for biochemists in search of a membrane protein to clone and explain XLH, for example. Let us suppose the transporter affected in XLH is cloned. Will it be the product of the XLH (or Hyp or Gy) locus? One will not know until the transporter gene is mapped. There is no question of the X-chromosome locus product being protein kinase C for example, since it maps to autosomes. But where does one start in the search for the X-chromosome locus? With the elusive putative diffusible factor or with the transporter, or perhaps with an enzyme in vitamin D hormone metabolism? Which goes to say that it is necessary to know the phenotype to arrive at the right locus. Or is it? Sufficient physical mapping of region Xp22.31-p21.3 will eventually lead to positional cloning of the Hyp gene. What will it be?(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H S Tenenhouse
- McGill University-Montreal Children's Hospital Research Institute, DeBelle Laboratory for Biochemical Genetics, Department of Pediatrics and Biology, Quebec, Canada
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38
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Scriver CR, Tenenhouse HS. X-linked hypophosphataemia: a homologous phenotype in humans and mice with unusual organ-specific gene dosage. J Inherit Metab Dis 1992; 15:610-24. [PMID: 1528020 DOI: 10.1007/bf01799618] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
XLH (X-linked hypophosphataemia, gene symbol HYP, McKusick 307800, 307810) and its murine counterparts (Hyp and Gy) map to a conserved segment on the X-chromosome (Xp 22.31-p.21.3, human; distal X, mouse). Gene dosage has received relatively little attention in the long history of research on this disease, which began over 50 years ago. Bone and teeth are sites of the principal disease manifestations in XLH (rickets, osteomalacia, interglobular dentin). Newer measures of quantitative XLH phenotypes reveal gene dose effects in bone and teeth with heterozygous values distributed between those in mutant hemizygotes and normal homozygotes. On the other hand, serum phosphate concentrations (which are low in the mutant phenotype and thereby contribute to bone and tooth phenotypes) do not show gene dosage. In Hyp mice serum values in mutant hemizygotes, mutant homozygotes and heterozygotes are similar. Phosphate homeostasis reflects its renal conservation. Renal absorption of phosphate on a high-affinity, Na+ ion-gradient coupled system in renal brush border membrane is impaired and gene dosage is absent at this level; the mutant phenotype is fully dominant. Synthesis and degradation of 1,25(OH)2D are also abnormal in XLH (and Hyp), but gene dosage in these parameters has not yet been measured. An (unidentified) inhibitory trans-acting product of the X-linked locus, affecting phosphate transport and vitamin D metabolism, acting perhaps through cytosolic protein kinase C, could explain the renal phenotype. But why would it have a normal gene dose effect in bone and teeth? Since the locus may have duplicated (to form Hyp and Gy), and shows evidence of variable expression in different organs (inner ear, bone/teeth, kidney), it may have been recruited during evolution to multiple functions.
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Affiliation(s)
- C R Scriver
- Department of Biology, McGill University, Montreal, Quebec, Canada
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39
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Oliveri MB, Cassinelli H, Bergadá C, Mautalen CA. Bone mineral density of the spine and radius shaft in children with X-linked hypophosphatemic rickets (XLH). BONE AND MINERAL 1991; 12:91-100. [PMID: 2015415 DOI: 10.1016/0169-6009(91)90038-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) is characterized by inadequate skeletal mineralization. The bone mineral density (BMD) of the radius shaft and the lumbar spine was determined in 13 children with XLH. Ten patients were on treatment, whereas three patients had discontinued treatment 20-32 months prior to this study. Two of them had radiological evidence of rickets. The radius shaft BMD was significantly diminished: Z score was -1.33 +/- 0.89 (P less than 0.001), while the BMD of lumbar spine was significantly augmented (Z score +1.95 +/- 1.17, P less than 0.001). A positive correlation was found between the Z scores for the BMD of the radius shaft and spine. The two patients with overt rickets had lower radius shaft BMD values and a lesser increment of BMD of the spine. The BMD deficit of cortical bone may be related to the lack of efficacy of the treatment and/or to an intrinsic defect of the bone on this disease. On the other hand, the augmented BMD of the lumbar spine might reflect the overabundance of partially mineralized osteoid. The determination of the BMD of the radius shaft by SPA was a sensitive method for detecting abnormalities of the bone mass in XLH patients under treatment without radiological signs of rickets.
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Affiliation(s)
- M B Oliveri
- Laboratorio de Osteopatías Médicas, Hospital de Clinicas, Centro de Investigaciones Endocrinológicas, Buenos Aires, Argentina
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40
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Scriver CR, Tenenhouse HS. Conserved loci on the X chromosome confer phosphate homeostasis in mice and humans. Genet Res (Camb) 1990; 56:141-52. [PMID: 2177024 DOI: 10.1017/s0016672300035229] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Several genes expressed in kidney and other tissues determine phosphate homeostasis in extracellular fluid. The major form of inherited hypophosphatemia in humans involves an X-linked locus (HPDR, Xp22.31-p21.3). It has two murine homologues (Hyp and Gy) which map to closely-linked but separate loci (crossover value 0.4%-0.8%). Both murine mutations impair Na(+)-phosphate cotransport in renal brush border membrane; an associated renal disorder of 1,25-dihydroxyvitamin D3 (1,25(OH)2D) metabolism has been characterized in Hyp mice. Whereas experiments with cultured Hyp renal epithelium indicate that the gene is expressed in kidney, studies showing the development of the mutant renal phenotype in normal mice parabiosed to Hyp mice implicate a circulating factor; these findings can be reconciled if the humoral factor is of renal origin. The gene dose effect of HPDR, Hyp and Gy on serum phosphorus values is consistently deviant and heterozygotes resemble affected hemizygotes. The deviant effect is also seen on renal phosphate transport; all mutant females (Hyp/Hyp and Hyp/+) have similar phenotypes. On the other hand, there is a normal gene dose effect of HPDR in mineralized tissue; tooth PRATIO (pulp area/tooth area) values for heterozygotes are distributed between those for affected males and normals. The tooth data imply that the X chromosome locus is expressed in both renal and non-renal cells. The polypeptide product of the X chromosome gene(s) is still unknown.
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Affiliation(s)
- C R Scriver
- DeBelle Laboratory for Biochemical Genetics, McGill University-Montreal Children's Hospital Research Institute
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Nakajima S, Yamaoka K, Yamamoto T, Okada S, Tanaka H, Seino Y. Decreased concentration of 1,25-dihydroxyvitamin D3 receptors in peripheral mononuclear cells of patients with X-linked hypophosphatemic rickets: effect of phosphate supplementation. BONE AND MINERAL 1990; 10:201-9. [PMID: 2171704 DOI: 10.1016/0169-6009(90)90262-e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Abnormal renal tubular phosphate transport is considered to be the primary defect in X-linked hypophosphatemic rickets (XLH). However, the resistance to vitamin D treatment in XLH cannot be explained by hypophosphatemia alone. Since most of the actions of vitamin D are mediated by its receptors (VDR), abnormalities of VDR have been postulated in XLH. In order to investigate this possibility, we measured the concentration of VDR in PHA-activated peripheral mononuclear cells from 10 XLH patients. Patients without phosphate supplementation showed significantly lower concentration (21.7 +/- 5.1 fmol/mg protein, mean +/- SEM) compared to the normal controls (60.7 +/- 4.0). On the contrary, there was no significant difference between the phosphate-supplemented patients (58.3 +/- 2.7) and controls. There was a significant positive correlation between VDR concentration and serum phosphate (P less than 0.05). In two patients, VDR was increased after daily phosphate supplementation was started. These results indicate that a decreased concentration of VDR secondary to persistent hypophosphatemia is one of the causes of vitamin D resistance in XLH.
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Affiliation(s)
- S Nakajima
- Department of Pediatrics, Osaka University School of Medicine, Japan
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42
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Abstract
Use of 1,25(OH)2D3 (calcitriol) can be of benefit in the treatment of two hereditary types of rickets and osteomalacia, vitamin D dependency type I (VDD1) and X-linked hypophosphatemic vitamin D-resistant rickets (HPDR). VDD1 is due to inadequate activation of 25(OH)D to 1,25(OH)2D, leading to very low circulating levels of 1,25(OH)2D in plasma; the basic abnormality appears to be an alteration in renal 1 alpha-hydroxylase activity. In VDD1, replacement therapy with calcitriol results in complete correction of the abnormal phenotype. By contrast, in HPDR, plasma levels of 25(OH)D and 1,25(OH)2D are in the normal range, although it has been demonstrated that the ability of patients to produce 1,25(OH)2D under conditions of stress is impaired. When started early in life, the use of phosphate salts in HPDR generally results in healing of rickets, normal growth, and correction of lower limb deformities. However, osteomalacia is not corrected by treatment with phosphate, either alone or in combination with vitamin D. By pharmacologically increasing the level of 1,25(OH)2D3 in these patients, there is often a dramatic improvement in the appearance of the trabecular surface, leading to correction of the osteomalacic component of HPDR; in addition, the secondary hyperparathyroidism observed in previous patients treated with phosphate and vitamin D is easier to control. Closed medical follow-up allows the prevention of renal damage that could result from long-term administration of calcitriol.
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Affiliation(s)
- F H Glorieux
- Genetics Unit, Shriners Hospital, Montréal, Québec, Canada
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43
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Clarke GD, Kainer G, Conway WF, Chan JC. Intramyocellular phosphate metabolism in X-linked hypophosphatemic rickets. J Pediatr 1990; 116:288-92. [PMID: 2299505 DOI: 10.1016/s0022-3476(05)82895-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- G D Clarke
- Department of Radiology, Medical College of Virginia, Richmond 23298-0498
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Affiliation(s)
- M Levi
- Department of Internal Medicine, University of Texas, Southwestern Medical Center, Dallas
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Block JE, Piel CF, Selvidge R, Genant HK. Familial hypophosphatemic rickets: bone mass measurements in children following therapy with calcitriol and supplemental phosphate. Calcif Tissue Int 1989; 44:86-92. [PMID: 2492895 DOI: 10.1007/bf02556466] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Familial hypophosphatemic rickets is characterized by defective skeletal mineralization resulting in abnormal growth and development. The pathologic and radiologic correlates of this syndrome have been given some investigation, but the effect of this mineralization defect on bone mineral density has not been adequately assessed. We measured axial and appendicular bone mineral in 17 children (mean age 5.59 +/- 4.87) with familial hypophosphatemia at baseline and at 6-month intervals after initiation of therapy with vitamin D3 (calcitriol) and phosphate supplementation. Noninvasive quantitative techniques included single photon absorptiometry (SPA) of the radius, combined cortical thickness (CCT) of the second metacarpal, and quantitative computed tomography (QCT) of vertebral trabecular bone. Thoraco-lumbar and hand/wrist radiographs were qualitatively assessed for the prevalence and severity of osteosclerosis, rickets, and other parameters indicative of metabolic bone disease as well as skeletal age. Quantitative determinations of bone mineral by each technique were compared with normal values for age and sex, and individual standardized scores (z-scores) were calculated at each measurement interval. Standard scores were also calculated for bone age-adjusted mineral values. At baseline, spinal trabecular bone by QCT was not significantly different from normal values; however, measurements of peripheral cortical bone by either SPA or CCT were significantly lower than values for normal children of the same age and sex (P = 0.05 and P = 0.01, respectively). Following therapy with calcitriol and phosphate, peripheral bone mass was not shown to improve significantly when contiguous standard scores were compared even when values were adjusted for bone age.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J E Block
- Department of Radiology, University of California, San Francisco 94143
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Goodyer PR, Kronick JB, Jequier S, Reade TM, Scriver CR. Nephrocalcinosis and its relationship to treatment of hereditary rickets. J Pediatr 1987; 111:700-4. [PMID: 2822887 DOI: 10.1016/s0022-3476(87)80245-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Renal ultrasonography was performed on 23 patients with X-linked hypophosphatemic rickets (XLH) and 11 patients with autosomal recessive vitamin D-dependent rickets (ARVDD). A pattern of increased echogenicity of the renal pyramids (ERP) was identified in 11/23 patients with XLH and 3/11 patients with ARVDD; this ultrasonographic finding has previously been associated with medullary nephrocalcinosis. Patients with XLH and ERP had significantly higher mean serum calcium and phosphate concentrations, more frequent episodes of hypercalcemia, and higher doses of oral vitamin D and phosphate during the first 3 years of therapy. Episodes of hypercalcemia were more frequent when patients received higher doses of vitamin D2 (greater than 4000 IU/kg/day) or 1,25-dihydroxycholecalciferol (greater than 40 ng/kg/day). Episodes of hypercalciuria were significantly increased at doses of greater than 20 ng/kg/day 1,25-dihydroxycholecalciferol. In patients with ARVDD, ERP was also correlated with vitamin D dose and frequency of hypercalcemia episodes. ERP was not associated with an elevation of serum creatinine or loss of urinary concentrating ability in either patient group.
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Affiliation(s)
- P R Goodyer
- Division of Nephrology, McGill University-Montreal Children's Hospital Research Institute, Quebec
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Boneh A, Reade TM, Scriver CR, Rishikof E. Audiometric evidence for two forms of X-linked hypophosphatemia in humans, apparent counterparts of Hyp and Gy mutations in mouse. AMERICAN JOURNAL OF MEDICAL GENETICS 1987; 27:997-1003. [PMID: 3425609 DOI: 10.1002/ajmg.1320270434] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Two forms of X-linked hypophosphatemia occur in the mouse. One form, caused by the Hyp gene, is a counterpart of human X-linked hypophosphatemic "vitamin D-resistant rickets". The other, recently characterized, is caused by a different gene (Gy) closely linked to Hyp on the mouse X-chromosome. The Gy mutation also impairs cochlear function in the mouse. We measured hearing in 22 patients with X-linked hypophosphatemia; five, including 2 mother-son pairs, had sensorineural hearing deficits due to cochlear dysfunction. We suggest the disease in these persons may be the human counterpart of the Gy phenotype in the mouse, which implies there are 2 forms of X-linked hypophosphatemia in humans.
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Affiliation(s)
- A Boneh
- Department of Pediatrics, Montreal Children's Hospital, Quebec
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Meyer RA, Meyer MH, Gray RW, Bruns ME. Evidence that low plasma 1,25-dihydroxyvitamin D causes intestinal malabsorption of calcium and phosphate in juvenile X-linked hypophosphatemic mice. J Bone Miner Res 1987; 2:67-82. [PMID: 3455158 DOI: 10.1002/jbmr.5650020111] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
X-linked hypophosphatemic (Hyp) mice are a model for human sex-linked vitamin D-resistant rickets. We have reported intestinal malabsorption of calcium in young Hyp mice, and in this report we have explored the mechanism for it. To test for resistance of the intestine to 1,25(OH)2 vitamin D3, this hormone was continually infused via osmotic minipumps into 4-week-old normal and Hyp mice at 0, 17, 50 or 150 ng/kg/day. After 3 days, 45Ca and inorganic 32P were administered by gavage, and the mice were sacrificed on the fifth day. The Hyp mice showed responses to the hormone equivalent to the normal mice in terms of increased intestinal absorption of both 45Ca and 32P, increased plasma isotope levels, increased femoral isotope content, and increased duodenal and renal 9 kD vitamin D-dependent calcium-binding protein (calbindin-D9K; CaBP). Plasma 1,25(OH)2D was measured in these mice. There were significant correlations of plasma 1,25(OH)2D to the intestinal absorption of 45Ca and 32P and to duodenal and renal CaBP. Plasma 1,25(OH)2D was also measured in stock normal and Hyp mice and was found to be lower in 4-week-old Hyp mice than in 4-week-old normal mice (113 +/- 10 pM (n = 18) vs. 67 +/- 10 (n = 20), normal vs. Hyp, p less than .01), but unchanged at 13 weeks of age (77 +/- 13 (n = 13) vs. 70 +/- 15 (n = 15), NS). This observed difference in plasma 1,25(OH)2D between normal and Hyp mice at 4 weeks of age was sufficient to explain the observed normal-to-Hyp differences in intestinal absorption of 45Ca and duodenal and renal CaBP. It also explained 72 +/- 18% of the observed difference in 32P absorption. We conclude that Hyp mouse intestine is not resistant to 1,25(OH)2D and that the lower plasma 1,25(OH)2D of 4-week-old Hyp mice causes intestinal malabsorption of calcium and phosphate.
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Affiliation(s)
- R A Meyer
- Department of Basic Sciences, School of Dentistry, Marquette University, Milwaukee, WI 53233
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50
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Abstract
Fifty-one patients aged 1 year to 56 years with metabolic bone disease underwent renal ultrasound. Medullary nephrocalcinosis was found in nine of 24 patients with X-linked hypophosphatemic rickets and is considered to be iatrogenic, related to vitamin D therapy. Another three in this group of 24 with both medullary and cortical increased renal echogenicity had suffered from repeated episodes of vitamin D intoxication and had secondary hyperparathyroidism. Nephrocalcinosis was less frequent in patients with treated vitamin D-dependent rickets or hypophosphatemic bone disease where generally smaller doses of vitamin D are given. Patients with pseudohypoparathyroidism, on small doses of vitamin D, had a normal renal ultrasound. In cystinosis and Fanconi's syndrome, the kidneys are small, echodense (both the cortex and medulla) with a tendency to cyst formation.
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