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Bernardor J, Flammier S, Salles JP, Amouroux C, Castanet M, Lienhardt A, Martinerie L, Damgov I, Linglart A, Bacchetta J. Off-label use of cinacalcet in pediatric primary hyperparathyroidism: A French multicenter experience. Front Pediatr 2022; 10:926986. [PMID: 36090548 PMCID: PMC9449487 DOI: 10.3389/fped.2022.926986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 07/11/2022] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Cinacalcet is a calcimimetic approved in adults with primary hyperparathyroidism (PHPT). Few cases reports described its use in pediatric HPT, with challenges related to the risk of hypocalcemia, increased QT interval and drug interactions. In this study, we report the French experience in this setting. METHODS We retrospectively analyzed data from 18 pediatric patients from 7 tertiary centers who received cinacalcet for PHPT. The results are presented as median (interquartile range). RESULTS At a median age of 10.8 (2.0-14.4) years, 18 patients received cinacalcet for primary HPT (N = 13 inactive CASR mutation, N = 1 CDC73 mutation, N = 1 multiple endocrine neoplasia type 1, N=3 unknown etiology). Cinacalcet was introduced at an estimated glomerular filtration rate (eGFR) of 120 (111-130) mL/min/1.73 m2, plasma calcium of 3.04 (2.96-3.14) mmol/L, plasma phosphate of 1.1 (1.0-1.3) mmol/L, age-standardized (z score) phosphate of -3.0 (-3.5;-1.9), total ALP of 212 (164-245) UI/L, 25-OHD of 37 (20-46) ng/L, age-standardized (z score) ALP of -2.4 (-3.7;-1.4), PTH of 75 (59-123) ng/L corresponding to 1.2 (1.0-2.3)-time the upper limit for normal (ULN). The starting daily dose of cinacalcet was 0.7 (0.6-1.0) mg/kg, with a maximum dose of 1.0 (0.9-1.4) mg/kg per day. With a follow-up of 2.2 (1.3-4.3) years on cinacalcet therapy, PTH and calcium significantly decreased to 37 (34-54) ng/L, corresponding to 0.8 (0.5-0.8) ULN (p = 0.01), and 2.66 (2.55-2.90) mmol/L (p = 0.002), respectively. In contrast, eGFR, 25-OHD, ALP and phosphate and urinary calcium levels remained stable. Nephrocalcinosis was not reported but one patient displayed nephrolithiasis. Cinacalcet was progressively withdrawn in three patients; no side effects were reported. CONCLUSIONS Cinacalcet in pediatric HPT can control hypercalcemia and PTH without significant side effects.
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Affiliation(s)
- Julie Bernardor
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Centre de Référence des Maladies Rénales Rares, Filières de Santé Maladies Rares OSCAR, ORKID et ERKNet, Service de Néphrologie Rhumatologie et Dermatologie Pédiatriques, Hôpital Femme Mère Enfant, Bron, France.,INSERM UMR S1033 Research Unit, Lyon, France.,Service de Néphrologie Pédiatrique, CHU de Nice, Hôpital Archet, Nice, France.,Faculté de Médecine, Université Côte d'Azur, Nice, France
| | - Sacha Flammier
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Centre de Référence des Maladies Rénales Rares, Filières de Santé Maladies Rares OSCAR, ORKID et ERKNet, Service de Néphrologie Rhumatologie et Dermatologie Pédiatriques, Hôpital Femme Mère Enfant, Bron, France
| | - Jean-Pierre Salles
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Unité d'Endocrinologie, Génétique et Pathologies Osseuses, Filières Santé Maladies Rares OSCAR et BOND, Hôpital des Enfants, Toulouse, France
| | - Cyril Amouroux
- Service d'Endrocrinologie et Néphrologie Pédiatrique, Filière de Santé Maladies Rares OSCAR, Hôpital Arnaud de Villeneuve - CHU Montpellier, Université de Montpellier, Montpellier, France
| | - Mireille Castanet
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Département de Pédiatrie, Filière Santé Maladies Rares OSCAR, CHU Rouen, Rouen, France
| | | | - Laetitia Martinerie
- Service d'Endocrinologie Pédiatrique, Centre de Référence des Maladies Endocriniennes Rares de la Croissance et du Développement (CRMERCD), Hôpital Robert Debré, Assistance Publique - Hôpitaux de Paris, Paris, France
| | - Ivan Damgov
- Center for Pediatric and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany.,Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany
| | - Agnès Linglart
- AP-HP, Centre de référence des maladies rares du métabolisme du calcium et du phosphate, Plateforme d'expertise maladies rares Paris Saclay, filière OSCAR, EndoRare and BOND ERN, Hôpital de Bicêtre Paris Saclay, Le Kremlin-Bicêtre, France.,Université Paris-Saclay, AP-HP, Service d'endocrinologie et diabète de l'enfant, Service de médecine des adolescents, Hôpital de Bicêtre Paris Saclay, INSERM U1185, Le Kremlin-Bicêtre, France
| | - Justine Bacchetta
- Centre de Référence des Maladies Rares du Calcium et du Phosphore, Centre de Référence des Maladies Rénales Rares, Filières de Santé Maladies Rares OSCAR, ORKID et ERKNet, Service de Néphrologie Rhumatologie et Dermatologie Pédiatriques, Hôpital Femme Mère Enfant, Bron, France.,INSERM UMR S1033 Research Unit, Lyon, France.,Faculté de Médecine Lyon Est, Université de Lyon, Lyon, France
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2
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Giannini S, Bianchi ML, Rendina D, Massoletti P, Lazzerini D, Brandi ML. Burden of disease and clinical targets in adult patients with X-linked hypophosphatemia. A comprehensive review. Osteoporos Int 2021; 32:1937-1949. [PMID: 34009447 PMCID: PMC8510985 DOI: 10.1007/s00198-021-05997-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 05/06/2021] [Indexed: 11/17/2022]
Abstract
UNLABELLED X-linked hypophosphataemia (XLH) is a lifelong condition. Despite the mounting clinical evidence highlighting the long-term multi-organ sequelae of chronic phosphate wasting and consequent hypophosphatemia over the lifetime and the morbidities associated with adult age, XLH is still perceived as a paediatric disease. INTRODUCTION Children who have XLH need to transition from paediatric to adult healthcare as young adults. While there is general agreement that all affected children should be treated (if the administration and tolerability of therapy can be adequately monitored), there is a lack of consensus regarding therapy in adults. METHODS To provide guidance in both diagnosis and treatment of adult XLH patients and promote better provision of care for this potentially underserved group of patients, we review the available clinical evidence and discuss the current challenges underlying the transition from childhood to adulthood care to develop appropriate management and follow-up patterns in adult XLH patients. RESULTS AND CONCLUSIONS Such a multi-systemic lifelong disease would demand that the multidisciplinary approach, successfully experienced in children, could be transitioned to adulthood care with an integration of specialized sub-disciplines to efficiently control musculoskeletal symptoms while optimizing patients' QoL. Overall, it would be desirable that transition to adulthood care could be a responsibility shared by the paediatric and adult XLH teams. Pharmacological management should require an adequate balance between the benefits derived from the treatment itself with complicated and long-term monitoring and the potential risks, as they may differ across age strata.
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Affiliation(s)
- S Giannini
- Department of Medicine, Clinica Medica 1, University of Padova, Padova, Italy.
| | - M L Bianchi
- Experimental Laboratory for Children's Bone Metabolism Research, Bone Metabolism Unit, Istituto Auxologico Italiano IRCCS, Milano, Italy
| | - D Rendina
- Department of Clinical Medicine and Surgery, Federico II University, Napoli, Italy
| | - P Massoletti
- Medical Affairs, Kyowa Kyrin, Basiglio, (MI), Italy
| | - D Lazzerini
- Medical Affairs, Kyowa Kyrin, Basiglio, (MI), Italy
| | - M L Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Firenze, Firenze, Italy
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3
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Cavaco D, Amaro P, Simões-Pereira J, Pereira MC. X-Linked Hypophosphatemic Rickets: Report of a Novel PHEX Mutation and Cinacalcet as Adjuvant Therapy in the Mineral Metabolism Control. Mod Rheumatol Case Rep 2021; 6:145-149. [PMID: 34561702 DOI: 10.1093/mrcr/rxab031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 04/24/2021] [Accepted: 09/01/2021] [Indexed: 12/24/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) is a rare disease caused by a mutation in the PHEX gene, located on the X chromosome. This gene encodes the phosphate regulating endopeptidase, and its inactivation leads to increased levels of circulating phosphatonins responsible for renal phosphate loss. The treatment of XLH is still carried out with long-term administration of phosphate and calcitriol, which can be complicated by hyperparathyroidism, nephrocalcinosis, renal failure and hypertension. We describe the case of a four-decades follow-up patient with XLH. When she was diagnosed, at 19, due to bone pain and deformities, she was put on therapy with phosphorus and cholecalciferol. Despite the clinical improvement, serum phosphorus remained difficult to control. At the age of 44, she developed tertiary hyperparathyroidism and was submitted to parathyroidectomy. Five years later, parathyroid hyperfunction recurred. This time, cinacalcet was started, 30 mg alternating with 60 mg/day. Currently, she is 59 years-old and remains with controlled mineral metabolism. The genetic study of this patient revealed a nonsense heterozygous mutation (c.501G> A) in PHEX gene that was not previously described. In this case, the off-label use of cinacalcet resulted in the normalization of serum PTH and phosphorus levels, eliminated recurrent secondary hyperparathyroidism, which aggravates the bone fragility inherent to XLH and prevented a new parathyroidectomy. This report also adds important information to the genetic basis of XLH with the identification of a new nonsense mutation of the PHEX gene.
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Affiliation(s)
- Daniela Cavaco
- Department of Endocrinology, Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisbon, Portugal
| | - Pedro Amaro
- Department of Orthopaedic Surgery, Hospital Beatriz Ângelo, Lisbon, Portugal
| | - Joana Simões-Pereira
- Department of Endocrinology, Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisbon, Portugal.,NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Maria Conceição Pereira
- Department of Endocrinology, Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisbon, Portugal
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Papadopoulou A, Bountouvi E, Karachaliou FE. The Molecular Basis of Calcium and Phosphorus Inherited Metabolic Disorders. Genes (Basel) 2021; 12:genes12050734. [PMID: 34068220 PMCID: PMC8153134 DOI: 10.3390/genes12050734] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Calcium (Ca) and Phosphorus (P) hold a leading part in many skeletal and extra-skeletal biological processes. Their tight normal range in serum mirrors their critical role in human well-being. The signalling “voyage” starts at Calcium Sensing Receptor (CaSR) localized on the surface of the parathyroid glands, which captures the “oscillations” of extracellular ionized Ca and transfers the signal downstream. Parathyroid hormone (PTH), Vitamin D, Fibroblast Growth Factor (FGF23) and other receptors or ion-transporters, work synergistically and establish a highly regulated signalling circuit between the bone, kidneys, and intestine to ensure the maintenance of Ca and P homeostasis. Any deviation from this well-orchestrated scheme may result in mild or severe pathologies expressed by biochemical and/or clinical features. Inherited disorders of Ca and P metabolism are rare. However, delayed diagnosis or misdiagnosis may cost patient’s quality of life or even life expectancy. Unravelling the thread of the molecular pathways involving Ca and P signaling, we can better understand the link between genetic alterations and biochemical and/or clinical phenotypes and help in diagnosis and early therapeutic intervention.
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Abstract
Fibroblast growth factor 23 (FGF23), one of the endocrine fibroblast growth factors, is a principal regulator in the maintenance of serum phosphorus concentration. Binding to its cofactor αKlotho and a fibroblast growth factor receptor is essential for its activity. Its regulation and interaction with other factors in the bone-parathyroid-kidney axis is complex. FGF23 reduces serum phosphorus concentration through decreased reabsorption of phosphorus in the kidney and by decreasing 1,25 dihydroxyvitamin D (1,25(OH)2D) concentrations. Various FGF23-mediated disorders of renal phosphate wasting share similar clinical and biochemical features. The most common of these is X-linked hypophosphatemia (XLH). Additional disorders of FGF23 excess include autosomal dominant hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets, fibrous dysplasia, and tumor-induced osteomalacia. Treatment is challenging, requiring careful monitoring and titration of dosages to optimize effectiveness and to balance side effects. Conventional therapy for XLH and other disorders of FGF23-mediated hypophosphatemia involves multiple daily doses of oral phosphate salts and active vitamin D analogs, such as calcitriol or alfacalcidol. Additional treatments may be used to help address side effects of conventional therapy such as thiazides to address hypercalciuria or nephrocalcinosis, and calcimimetics to manage hyperparathyroidism. The recent development and approval of an anti-FGF23 antibody, burosumab, for use in XLH provides a novel treatment option.
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Affiliation(s)
- Anisha Gohil
- Indiana University School of Medicine, Riley Hospital for Children, Fellow, Endocrinology and Diabetes, 705 Riley Hospital Drive, Room 5960, Indianapolis, IN 46202, USA, E-mail:
| | - Erik A Imel
- Indiana University School of Medicine, Riley Hospital for Children, Associate Professor of Medicine and Pediatrics, 1120 West Michigan Street, CL 459, Indianapolis, IN 46202, USA
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Imel EA, Biggin A, Schindeler A, Munns CF. FGF23, Hypophosphatemia, and Emerging Treatments. JBMR Plus 2019; 3:e10190. [PMID: 31485552 PMCID: PMC6715782 DOI: 10.1002/jbm4.10190] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/13/2019] [Accepted: 02/26/2019] [Indexed: 01/03/2023] Open
Abstract
FGF23 is an important hormonal regulator of phosphate homeostasis. Together with its co-receptor Klotho, it modulates phosphate reabsorption and both 1α-hydroxylation and 24-hydroxylation in the renal proximal tubules. The most common FGF23-mediated hypophosphatemia is X-linked hypophosphatemia (XLH), caused by mutations in the PHEX gene. FGF23-mediated forms of hypophosphatemia are characterized by phosphaturia and low or low-normal calcitriol concentrations, and unlike nutritional rickets, these cannot be cured with nutritional vitamin D supplementation. Autosomal dominant and autosomal recessive forms of FGF23-mediated hypophosphatemias show a similar pathophysiology, despite a variety of different underlying genetic causes. An excess of FGF23 activity has also been associated with a number of other conditions causing hypophosphatemia, including tumor-induced osteomalacia, fibrous dysplasia of the bone, and cutaneous skeletal hypophosphatemia syndrome. Historically phosphate supplementation and therapy using analogs of highly active vitamin D (eg, calcitriol, alfacalcidol, paricalcitol, eldecalcitol) have been used to manage conditions involving hypophosphatemia; however, recently a neutralizing antibody for FGF23 (burosumab) has emerged as a promising treatment agent for FGF23-mediated disorders. This review discusses the progression of clinical trials for burosumab for the treatment of XLH and its recent availability for clinical use. Burosumab may have potential for treating other conditions associated with FGF23 overactivity, but these are not yet supported by trial data. © 2019 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)
- Erik A Imel
- Division of EndocrinologyIndiana University School of Medicine, Indianapolis, INUSA
| | - Andrew Biggin
- The University of Sydney Children's Hospital Westmead Clinical School, University of SydneySydneyAustralia
- Department of EndocrinologyThe Children's Hospital at WestmeadWestmeadAustralia
| | - Aaron Schindeler
- The University of Sydney Children's Hospital Westmead Clinical School, University of SydneySydneyAustralia
- Orthopaedic Research Unit, The Children's Hospital at WestmeadWestmeadAustralia
| | - Craig F Munns
- The University of Sydney Children's Hospital Westmead Clinical School, University of SydneySydneyAustralia
- Department of EndocrinologyThe Children's Hospital at WestmeadWestmeadAustralia
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VanSickle JS, Srivastava T, Alon US. Use of calcimimetics in children with normal kidney function. Pediatr Nephrol 2019; 34:413-422. [PMID: 29552709 DOI: 10.1007/s00467-018-3935-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 11/26/2022]
Abstract
The calcium-sensing receptor (CaSR) plays an important role in the homeostasis of serum ionized calcium by regulating parathyroid hormone (PTH) secretion and tubular calcium handling. Calcimimetics, which act by allosteric modulation of the CaSR, mimic hypercalcemia resulting in suppression of PTH release and increase in calciuria. Mostly used in children to treat secondary hyperparathyroidism associated with advanced renal failure, we have shown that calcimimetics can also be successfully used in children with bone and mineral disorders in which elevated PTH plays a detrimental role in skeletal pathophysiology in the face of normal kidney function. The current review briefly discusses the role of the CaSR and calcimimetics in calcium homeostasis, and then addresses the potential applications of calcimimetics in children with normal kidney function with disorders in which suppression of PTH is beneficial.
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Affiliation(s)
- Judith Sebestyen VanSickle
- Bone and Mineral Disorders Clinic, Division of Nephrology, Children's Mercy Hospital, University of Missouri at Kansas City, 2401Gillham Road, Kansas City, MO, 64108, USA
| | - Tarak Srivastava
- Bone and Mineral Disorders Clinic, Division of Nephrology, Children's Mercy Hospital, University of Missouri at Kansas City, 2401Gillham Road, Kansas City, MO, 64108, USA
- Renal Research Laboratory, Research and Development, Kansas City VA Medical Center, Kansas City, MO, 64128, USA
| | - Uri S Alon
- Bone and Mineral Disorders Clinic, Division of Nephrology, Children's Mercy Hospital, University of Missouri at Kansas City, 2401Gillham Road, Kansas City, MO, 64108, USA.
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8
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Imel EA, White KE. Pharmacological management of X-linked hypophosphataemia. Br J Clin Pharmacol 2018; 85:1188-1198. [PMID: 30207609 DOI: 10.1111/bcp.13763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/05/2018] [Accepted: 09/05/2018] [Indexed: 12/25/2022] Open
Abstract
The most common heritable disorder of renal phosphate wasting, X-linked hypophosphataemia (XLH), was discovered to be caused by inactivating mutations in the phosphate regulating gene with homology to endopeptidases on the X-chromosome (PHEX) gene in 1995. Although the exact molecular mechanisms by which PHEX mutations cause disturbed phosphate handling in XLH remain unknown, focus for novel therapies has more recently been based upon the finding that the bone-produced phosphaturic hormone fibroblast growth factor-23 is elevated in XLH patient plasma. Previous treatment strategies for XLH were based upon phosphate repletion plus active vitamin D analogues, which are difficult to manage, fail to address the primary pathogenesis of the disease, and can have deleterious side effects. A novel therapy for XLH directly targeting fibroblast growth factor-23 via a humanized monoclonal antibody (burosumab-twza/CRYSVITA, henceforth referred to just as burosumab) has emerged as an effective, and recently approved, pharmacological treatment for both children and adults. This review will provide an overview of the clinical manifestations of XLH, the molecular pathophysiology, and summarize its current treatment.
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Affiliation(s)
- Erik A Imel
- Department of Medicine, Division of Endocrinology and Metabolism, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Pediatrics, Section of Endocrinology and Diabetology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kenneth E White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN, USA
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Michałus I, Rusińska A. Rare, genetically conditioned forms of rickets: Differential diagnosis and advances in diagnostics and treatment. Clin Genet 2018; 94:103-114. [DOI: 10.1111/cge.13229] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 02/01/2018] [Accepted: 02/02/2018] [Indexed: 12/21/2022]
Affiliation(s)
- I. Michałus
- Department of Propedeutics Pediatrics and Bone Metabolic Diseases; Medical University of Lodz; Lodz Poland
| | - A. Rusińska
- Department of Propedeutics Pediatrics and Bone Metabolic Diseases; Medical University of Lodz; Lodz Poland
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10
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Bacon S, Crowley R. Developments in rare bone diseases and mineral disorders. Ther Adv Chronic Dis 2018; 9:51-60. [PMID: 29344330 PMCID: PMC5761943 DOI: 10.1177/2040622317739538] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 10/04/2017] [Indexed: 12/16/2022] Open
Abstract
In the last decade, there have been a number of significant advances made in the field of rare bone diseases. In this review, we discuss the expansion of the classification system for osteogenesis imperfecta (OI) and the resultant increase in therapeutic options available for management of OI. Bisphosphonates remain the most widely used intervention for OI, although the effect on fracture rate reduction is equivocal. We review the other therapies showing promising results, including denosumab, teriparatide, sclerostin, transforming growth factor β inhibition and gene targeted approaches. X-linked hypophosphataemia (XLH) is the most common heritable form of osteomalacia and rickets caused by a mutation in the phosphate regulating endopeptidase gene resulting in elevated serum fibroblast growth factor 23 (FGF23) and decreased renal phosphate reabsorption. The traditional treatment is phosphate replacement. We discuss the development of a human anti-FGF23 antibody (KRN23) as a promising development in the treatment of XLH. The current management of primary hypoparathyroidism is replacement with calcium and active vitamin D. This can be associated with under or over replacement and its inherent complications. We review the use of recombinant parathyroid hormone (1-84), which can significantly reduce the requirements for calcium and vitamin D resulting in greater safety and quality of life for individuals with hypoparathyroidism. The use of receptor activator of nuclear factor κB ligand infusions in the treatment of a particular form of osteopetrosis and enzyme replacement therapy for hypophosphatasia are also discussed.
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