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Abstract
PURPOSE OF REVIEW In this paper, we review the pathogenesis and treatment of chronic kidney disease-mineral and bone disorder (CKD-MBD), especially as it relates to pediatric CKD patients. RECENT FINDINGS Disordered regulation of bone and mineral metabolism in CKD may result in fractures, skeletal deformities, and poor growth, which is especially relevant for pediatric CKD patients. Moreover, CKD-MBD may result in extra-skeletal calcification and cardiovascular morbidity. Early increases in fibroblast growth factor 23 (FGF23) levels play a key, primary role in CKD-MBD pathogenesis. Therapeutic approaches in pediatric CKD-MBD aim to minimize complications to the growing skeleton and prevent extra-skeletal calcifications, mainly by addressing hyperphosphatemia and secondary hyperparathyroidism. Ongoing clinical trials are focused on assessing the benefit of FGF23 reduction in CKD. CKD-MBD is a systemic disorder that has significant clinical implications. Treatment of CKD-MBD in children requires special consideration in order to maximize growth, optimize skeletal health, and prevent cardiovascular disease.
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Affiliation(s)
- Mark R Hanudel
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
- Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
| | - Isidro B Salusky
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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52
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Abstract
PURPOSE OF REVIEW In this paper, we review the epidemiology, diagnosis, and pathogenesis of fractures and renal osteodystrophy. RECENT FINDINGS The role of bone quality in the pathogenesis of fracture susceptibility in chronic kidney disease (CKD) is beginning to be elucidated. Bone quality refers to bone material properties, such as cortical and trabecular microarchitecture, mineralization, turnover, microdamage, and collagen content and structure. Recent data has added to our understanding of the effects of CKD on alterations to bone quality, emerging data on the role of abnormal collagen structure on bone strength, the potential of non-invasive methods to inform our knowledge of bone quality, and how we can use these methods to inform strategies that protect against bone loss and fractures. However, more prospective data is required. CKD is associated with abnormal bone quality and strength which results in high fracture incidence.
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Affiliation(s)
- Erin M B McNerny
- Indiana University School of Medicine, Indianapolis, IN, USA
- Division of Nephrology, Department of Medicine, Columbia University Medical Center, 622 West 168th Street, PH4-124, New York, NY, 10032, USA
| | - Thomas L Nickolas
- Indiana University School of Medicine, Indianapolis, IN, USA.
- Division of Nephrology, Department of Medicine, Columbia University Medical Center, 622 West 168th Street, PH4-124, New York, NY, 10032, USA.
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Hajizadeh N, Mehrkash M, Fahimi D, Qorbani M, Shafa N. Association of bone mineral density with biochemical markers of bone turnover in hemodialysis children. J Renal Inj Prev 2016; 5:174-8. [PMID: 27689118 PMCID: PMC5039984 DOI: 10.15171/jrip.2016.37] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 07/09/2016] [Indexed: 12/28/2022] Open
Abstract
Introduction: Although some descriptive and cross-sectional studies have been reported about bone mass in chronic kidney disease (CKD) children, only a few studies investigated markers of bone turnover and the bone mass measurements.
Objectives: The aim of this study was to evaluate the association between bone mineral density (BMD) and biochemical markers of bone turnover in hemodialysis (HD) children.
Patients and Methods: The children who had received dialysis for at least the preceding 6‐month were included. BMD was measured for total body, the lumbar spine and the femoral neck and the blood samples were tested to assess biochemical bone turnover markers.
Results: The study group was comprised of 27 patients with CKD, 9 males (33%) and 18 females (67%) with the mean±SD age of the subjects 14.9±4.5 years. Positive significant correlations of parathyroid hormone (PTH) with total body bone densitometry Z-score, lumbar spine and femoral neck Z-score(r=0.43, P=0.06; r=0.41, P=0.08 and r=0.45, P=0.05, respectively) was noted. In addition, positive significant correlations calcium and total body, lumbar spine and femoral neck Z-score (r=0.52, P=0.02; r=0.28, P=0.23 and r=0.36, P=0.12, respectively) was seen. Interestingly, a positive significant correlation between alkaline phosphatase (ALP) and lumbar spine Z-score was found (r=0.46, P=0.04), while the correlation of this parameter with total body and femoral neck Z-score was not significant (P>0.05).
Conclusion: In our study, majority of patients with CKD had low level of BMD. In addition, lower levels of calcium (Ca), phosphorus (P), PTH and 25 (OH) vitamins D in patients with abnormal BMD Z-scores were detected.
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Affiliation(s)
- Niloofar Hajizadeh
- Department of Pediatric Nephrology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehryar Mehrkash
- Department of Pediatric Nephrology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Daryoosh Fahimi
- Department of Pediatric Nephrology, Bahrami Children Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mostafa Qorbani
- Department of Community Medicine, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - Nina Shafa
- Iranian Resaerch Center on Ageing, University of Social Walfare and RehabilitationSciences,Tehran, Iran
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Denburg MR, Hoofnagle AN, Sayed S, Gupta J, de Boer IH, Appel LJ, Durazo-Arvizu R, Whitehead K, Feldman HI, Leonard MB. Comparison of Two ELISA Methods and Mass Spectrometry for Measurement of Vitamin D-Binding Protein: Implications for the Assessment of Bioavailable Vitamin D Concentrations Across Genotypes. J Bone Miner Res 2016; 31:1128-36. [PMID: 27250744 PMCID: PMC4945118 DOI: 10.1002/jbmr.2829] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 02/27/2016] [Accepted: 03/04/2016] [Indexed: 01/30/2023]
Abstract
Studies using vitamin D-binding protein (DBP) concentrations to estimate free and bioavailable vitamin D have increased dramatically in recent years. Combinations of two single-nucleotide polymorphisms (SNPs) produce three major DBP isoforms (Gc1f, Gc1s, and Gc2). A recent study showed that DBP concentrations quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) did not differ by race, whereas a widely used monoclonal enzyme-linked immunosorbent assay (ELISA) quantified DBP differentially by isoform, yielding significantly lower DBP concentrations in black versus white individuals. We compared measurements of serum DBP using a monoclonal ELISA, a polyclonal ELISA, and LC-MS/MS in 125 participants in the Chronic Renal Insufficiency Cohort (CRIC). Serum free and bioavailable 25OHD were calculated based on DBP concentrations from these three assays in homozygous participants, and race differences were compared. We confirmed that the monoclonal ELISA quantifies DBP differentially by isoform and showed that the polyclonal ELISA is not subject to this bias. Whereas ≤9% of the variability in DBP concentrations quantified using either LC-MS/MS or the polyclonal ELISA was explained by genotype, 85% of the variability in the monoclonal ELISA-based measures was explained by genotype. DBP concentrations measured by the monoclonal ELISA were disproportionately lower than LC-MS/MS-based results for Gc1f homozygotes (median difference -67%; interquartile range [IQR] -71%, -64%), 95% of whom were black. In contrast, the polyclonal ELISA yielded consistently and similarly higher measurements of DBP than LC-MS/MS, irrespective of genotype, with a median percent difference of +50% (IQR +33%, +65%). Contrary to findings using the monoclonal ELISA, DBP concentrations did not differ by race, and free and bioavailable 25OHD were significantly lower in black versus white participants based on both the polyclonal ELISA and LC-MS/MS, consistent with their lower total 25OHD. Future studies of DBP and free or bioavailable vitamin D metabolites should employ DBP assays that are not biased by DBP genotype. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Michelle R Denburg
- Department of Pediatrics, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew N Hoofnagle
- Department of Laboratory Medicine, Washingon University School of Medicine, Seattle, WA, USA
| | - Samir Sayed
- Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA
| | - Jayanta Gupta
- Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX, USA
| | - Ian H de Boer
- Department of Medicine, Washingon University School of Medicine, Seattle, WA, USA
| | - Lawrence J Appel
- Departments of Medicine, Epidemiology and International Health, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ramon Durazo-Arvizu
- Department of Public Health Sciences, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Krista Whitehead
- Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Harold I Feldman
- Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mary B Leonard
- Departments of Pediatrics and Medicine, Stanford University School of Medicine, Stanford, CA, USA
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El Desoky S, Farag YMK, Safdar E, Shalaby MA, Singh AK, Kari JA. Prevalence of Hyperparathyroidism, Mineral and Bone Disorders in Children with Advanced Chronic Kidney Disease. Indian J Pediatr 2016; 83:420-5. [PMID: 26830276 DOI: 10.1007/s12098-015-1986-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 12/09/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To identify the prevalence and risk factors for secondary hyperparathyroidism in children with advanced stages of chronic kidney disease (CKD). METHODS A retrospective cross-sectional observational study of clinical and laboratory data of pediatric patients with CKD stage 3, 4 was conducted from 2005 through 2013 at a single center in the Kingdom of Saudi Arabia. RESULTS One hundred nineteen children (60.5 % boys) with mean age of 10.1 ± 5.1 y were included in the study. The mean eGFR (estimated Glomerular Filtration Rate) was 18.3 ± 15.4 ml/min/1.73m(2) and the mean intact parathyroid hormone (iPTH) level was 62.2 ± 89.4 pmol/L. Patients with a high iPTH had lower eGFR than those who were euparathyroid (16 ± 13.4 vs. 29.7 ± 19 ml/min/1.73m(2), respectively; p = 0.006), had lower calcium levels (2.2 ± 0.3 vs. 2.4 ± 0.3 mmol/L; p = 0.03) and a lower bicarbonate level (21.2 ± 4.2 vs. 23.3 ± 3.2 mmol/L; p = 0.04). Three children with hyperparthyrodism (4.9 %) had fractures, 16 (26.2 %) had bone deformities compared to 5 in the euoparathyroid group (p = 0.012). Parathyroid hormone negatively correlated with the patient's eGFR (r = -0.55), serum calcium (r = -0.43), and positively correlated with serum phosphate (r = 0.38). CONCLUSIONS The single most important predictor of hyperparathyroidism in children in the present sample was eGFR.
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Affiliation(s)
- Sherif El Desoky
- Department of Pediatrics, King Abdulaziz University , PO Box 80215, Jeddah, 21589, Kingdom of Saudi Arabia
| | - Youssef M K Farag
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Eatidal Safdar
- Department of Pediatrics, King Abdulaziz University , PO Box 80215, Jeddah, 21589, Kingdom of Saudi Arabia
| | - Mohamed Ahmed Shalaby
- Department of Pediatrics, King Abdulaziz University , PO Box 80215, Jeddah, 21589, Kingdom of Saudi Arabia
| | - Ajay K Singh
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jameela A Kari
- Department of Pediatrics, King Abdulaziz University , PO Box 80215, Jeddah, 21589, Kingdom of Saudi Arabia.
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56
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Babayev R, Nickolas TL. Bone Disorders in Chronic Kidney Disease: An Update in Diagnosis and Management. Semin Dial 2015; 28:645-53. [DOI: 10.1111/sdi.12423] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Revekka Babayev
- Department of Medicine; Division of Nephrology; Columbia University Medical Center; New York City New York
| | - Thomas L. Nickolas
- Department of Medicine; Division of Nephrology; Columbia University Medical Center; New York City New York
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57
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Denburg MR, Bhan I. Vitamin D-Binding Protein in Health and Chronic Kidney Disease. Semin Dial 2015; 28:636-44. [PMID: 26332676 DOI: 10.1111/sdi.12422] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vitamin D-binding protein (DBP) is a multifunctional protein that has attracted increasing interest in recent years, largely because of its potential role in modulating the activity of vitamin D. Nearly all circulating vitamin D (~85-90%) circulates bound to DBP, with a smaller proportion bound to albumin, leaving <5% circulating freely. DBP may also play roles beyond vitamin D binding, with potential roles in the immune system and elsewhere. Numerous polymorphisms of DBP exist around the world, and recent studies have identified relevance of different DBP phenotypes in determining DBP concentration and vitamin D affinity. This review focuses on the known roles of DBP in health and kidney disease, and current views on the relevance of DBP polymorphisms.
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Affiliation(s)
- Michelle R Denburg
- Departments of Pediatrics and Epidemiology, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ishir Bhan
- Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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58
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Denburg MR, Kumar J, Jemielita T, Brooks ER, Skversky A, Portale AA, Salusky IB, Warady BA, Furth SL, Leonard MB. Fracture Burden and Risk Factors in Childhood CKD: Results from the CKiD Cohort Study. J Am Soc Nephrol 2015; 27:543-50. [PMID: 26139439 DOI: 10.1681/asn.2015020152] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 04/29/2015] [Indexed: 12/30/2022] Open
Abstract
Childhood chronic kidney disease (CHD) poses multiple threats to bone accrual; however, the associated fracture risk is not well characterized. This prospective cohort study included 537 CKD in Children (CKiD) participants. Fracture histories were obtained at baseline, at years 1, 3, and 5 through November 1, 2009, and annually thereafter. We used Cox regression analysis of first incident fracture to evaluate potential correlates of fracture risk. At enrollment, median age was 11 years, and 16% of patients reported a prior fracture. Over a median of 3.9 years, 43 males and 24 females sustained incident fractures, corresponding to 395 (95% confidence interval [95% CI], 293-533) and 323 (95% CI, 216-481) fractures per 10,000 person-years, respectively. These rates were 2- to 3-fold higher than published general population rates. The only gender difference in fracture risk was a 2.6-fold higher risk in males aged ≥15 years (570/10,000 person-years, adjusted P=0.04). In multivariable analysis, advanced pubertal stage, greater height Z-score, difficulty walking, and higher average log-transformed parathyroid hormone level were independently associated with greater fracture risk (all P≤0.04). Phosphate binder treatment (predominantly calcium-based) was associated with lower fracture risk (hazard ratio, 0.37; 95% CI, 0.15-0.91; P=0.03). Participation in more than one team sport was associated with higher risk (hazard ratio, 4.87; 95% CI, 2.21-10.75; P<0.001). In conclusion, children with CKD have a high burden of fracture. Regarding modifiable factors, higher average parathyroid hormone level was associated with greater risk of fracture, whereas phosphate binder use was protective in this cohort.
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Affiliation(s)
- Michelle R Denburg
- The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania;
| | - Juhi Kumar
- Weill Cornell Medical College, New York, New York
| | - Thomas Jemielita
- Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ellen R Brooks
- Ann and Robert Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Amy Skversky
- The Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, New York
| | - Anthony A Portale
- University of California, San Francisco School of Medicine, San Francisco, California
| | - Isidro B Salusky
- David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Bradley A Warady
- Children's Mercy Hospital, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri; and
| | - Susan L Furth
- The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Mary B Leonard
- Stanford University School of Medicine, Stanford, California
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59
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Abstract
Fractures are more common and are associated with greater morbidity and morality in patients with kidney disease than in members of the general population. Thus, it is troubling that in chronic kidney disease (CKD) patients there has been a paradoxical increase in fracture rates over the past 20 years compared to the general population. Increased fracture incidence in CKD patients may be driven in part by the lack of screening for fracture risk. In the general population, dual energy X-ray absorptiometry (DXA) is the clinical standard to stratify fracture risk, and its use has contributed to decreases in fracture incidence. In contrast, in CKD, fracture risk screening with DXA has been uncommon due to its unclear efficacy in predicting fracture and its inability to predict type of renal osteodystrophy. Recently, several prospective studies conducted in patients across the spectrum of kidney disease have demonstrated that bone mineral density measured by DXA predicts future fracture risk and that clinically relevant information regarding fracture risk is provided by application of the World Health Organization cutoffs for osteopenia and osteoporosis to DXA measures. Furthermore, novel high-resolution imaging tools, such as high-resolution peripheral quantitative computed tomography (HR-pQCT), have been used to elucidate the effects of kidney disease on cortical and trabecular microarchitecture and bone strength and to identify potential targets for strategies that protect against fractures. This review will discuss the updated epidemiology of fractures in CKD, fracture risk screening by DXA, and the utility of state-of-the art imaging methods to uncover the effects of kidney disease on the skeleton.
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Affiliation(s)
- Sophie A Jamal
- Women's College Research Institute, University of Toronto, Toronto, Canada
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60
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Gao Y, Zong K, Gao Z, Rubin MR, Chen J, Heymsfield SB, Gallagher D, Shen W. Magnetic resonance imaging-measured bone marrow adipose tissue area is inversely related to cortical bone area in children and adolescents aged 5-18 years. J Clin Densitom 2015; 18:203-8. [PMID: 25840474 PMCID: PMC4420702 DOI: 10.1016/j.jocd.2015.03.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/05/2015] [Accepted: 03/06/2015] [Indexed: 01/14/2023]
Abstract
Previous studies have shown an inverse correlation between bone marrow adipose tissue and bone mineral density in cancellous bone; however, such relationships in cortical bone are less studied, especially in children. A total of 185 healthy children and adolescents (76 females and 109 males, aged 5-18 years) were included in this study. Right femoral bone marrow adipose tissue area (BMA), right femoral cortical bone area (CBA), subcutaneous adipose tissue, visceral adipose tissue, and skeletal muscle were accessed by whole-body magnetic resonance imaging. In regression analysis with CBA as the dependent variable and BMA as the independent variable, BMA negatively contributed to CBA after adjusting for weight and total body fat or subcutaneous adipose tissue, visceral adipose tissue, and skeletal muscle (β = -0.201 to -0.272, p < 0.001). These results suggest an inverse relationship between BMA and CBA in children and adolescents after adjustment of body weight or body composition. The data support the hypothesis that a competitive relationship exists between bone and marrow fat in cortical bone and is consistent with a similar finding in cancellous bone in previous studies. Future research is needed to clarify the role of marrow fat in childhood fractures that are related to cortical bone quality.
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Affiliation(s)
- Yan Gao
- New York Obesity Research Center, Department of Medicine and Institute of Human Nutrition, Columbia University, New York, NY, USA
| | - Kuang Zong
- New York Obesity Research Center, Department of Medicine and Institute of Human Nutrition, Columbia University, New York, NY, USA
| | - Zackary Gao
- New York Obesity Research Center, Department of Medicine and Institute of Human Nutrition, Columbia University, New York, NY, USA
| | - Mishaela R Rubin
- Metabolic Bone Disease Unit, Columbia University, New York, NY, USA
| | - Jun Chen
- New York Obesity Research Center, Department of Medicine and Institute of Human Nutrition, Columbia University, New York, NY, USA
| | - Steven B Heymsfield
- Metabolism-Body Composition, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Dympna Gallagher
- New York Obesity Research Center, Department of Medicine and Institute of Human Nutrition, Columbia University, New York, NY, USA
| | - Wei Shen
- New York Obesity Research Center, Department of Medicine and Institute of Human Nutrition, Columbia University, New York, NY, USA.
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Rees L, Shroff R. The demise of calcium-based phosphate binders-is this appropriate for children? Pediatr Nephrol 2015; 30:2061-71. [PMID: 25543193 PMCID: PMC4623082 DOI: 10.1007/s00467-014-3017-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/06/2014] [Accepted: 11/12/2014] [Indexed: 01/16/2023]
Abstract
In children with chronic kidney disease (CKD) optimal control of mineral and bone disorder (MBD) is essential not only for the prevention of debilitating skeletal complications and for achieving adequate growth, but also for preserving long-term cardiovascular health. The growing skeleton is particularly vulnerable to the effects of CKD, and bone pain, fractures and deformities are common in children on dialysis. Defective bone mineralisation has been linked with ectopic calcification, which in turn leads to significant morbidity and mortality. Despite national and international guidelines for the management of CKD-MBD, the management of mineral dysregulation in CKD can be extremely challenging, and a significant proportion of patients have calcium, phosphate or parathyroid hormone levels outside the normal ranges. Clinical and experimental studies have shown that, in the setting of CKD, low serum calcium levels are associated with poor bone mineralisation, whereas high serum calcium levels can lead to arterial calcification, even in children. The role of calcium in CKD-MBD is the focus of this review.
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Affiliation(s)
- Lesley Rees
- Paediatric Nephrology, Great Ormond Street Hospital for Children, Great Ormond St, London, WC1N 3JH, UK.
| | - Rukshana Shroff
- Paediatric Nephrology, Great Ormond Street Hospital for Children, Great Ormond St, London, WC1N 3JH, UK
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Abstract
PURPOSE OF REVIEW Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a complex disorder of bone and mineral metabolism that results in an excess risk of fractures, cardiovascular events and mortality. The management of the bone disorder aspect of CKD-MBD may require bone biopsy to determine appropriate treatment strategies. However, it is unclear when biopsy may be necessary and whether or not state-of-the art imaging and serologic testing can supplant the bone biopsy as a tool to assist with management decisions. RECENT FINDINGS Advances in imaging methods now permit the noninvasive assessment of structural aspects of bone quality. Furthermore, common bone imaging tools, such as dual-energy X-ray absorptiometry, can be used to stratify for fracture risk. Circulating markers of bone turnover can be used to assess the risk of bone loss and fracture, but they are less useful in diagnosing the type of renal osteodystrophy. SUMMARY Although advances in imaging now permit the assessment of fracture risk more accurately in CKD patients, the assessment of the type of renal osteodystrophy remains poor without bone biopsy. The virtual bone biopsy will be possible only when we are able to noninvasively assess turnover with good accuracy. A bone biopsy is needed when the bone turnover is unclear.
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Affiliation(s)
- Revekka Babayev
- Department of Medicine, Columbia University Medical Center, New York, New York, USA
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63
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Abstract
PURPOSE OF REVIEW Disturbances in calcium-phosphate homeostasis play an important role in children with chronic kidney disease, and not only cause renal osteodystrophy but also result in increased cardiovascular morbidity and mortality. This review outlines the current aspects in the pathogenesis, diagnostic approach and treatment of renal osteodystrophy. RECENT FINDINGS The pathogenesis of renal osteodystrophy is under strong influence of the fibroblast growth factor 23/Klotho system, which is able to enhance phosphate excretion and reduce calcitriol synthesis in the kidney. Fibroblast growth factor 23 increases tissue calcinosis and is cardiotoxic, and is independently associated with mortality. Despite improvement in diagnostic imaging (bone density measurements), determination of biomarkers, mainly parathyroid hormone, still plays a central role. New treatment options resulted in improved bone health and also a reduction in mortality was achieved in adults with calcium-free phosphate binders. Substitution of active and inactive vitamin D is important and also has a beneficial effect on proteinuria. SUMMARY Knowledge about the biochemical and molecular mechanisms of renal osteodystrophy is increasing dramatically and has an impact not only to bone health but also overall morbidity and mortality. This will ultimately translate into further improved diagnostic approaches and novel treatment options.
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Sgambat K, Moudgil A. Optimization of Bone Health in Children before and after Renal Transplantation: Current Perspectives and Future Directions. Front Pediatr 2014; 2:13. [PMID: 24605319 PMCID: PMC3932433 DOI: 10.3389/fped.2014.00013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 02/11/2014] [Indexed: 11/29/2022] Open
Abstract
The accrual of healthy bone during the critical period of childhood and adolescence sets the stage for lifelong skeletal health. However, in children with chronic kidney disease (CKD), disturbances in mineral metabolism and endocrine homeostasis begin early on, leading to alterations in bone turnover, mineralization, and volume, and impairing growth. Risk factors for CKD-mineral and bone disorder (CKD-MBD) include nutritional vitamin D deficiency, secondary hyperparathyroidism, increased fibroblast growth factor 23 (FGF-23), altered growth hormone and insulin-like growth factor-1 axis, delayed puberty, malnutrition, and metabolic acidosis. After kidney transplantation, nutritional vitamin D deficiency, persistent hyperparathyroidism, tertiary FGF-23 excess, hypophosphatemia, hypomagnesemia, immunosuppressive therapy, and alteration of sex hormones continue to impair bone health and growth. As function of the renal allograft declines over time, CKD-MBD associated changes are reactivated, further impairing bone health. Strategies to optimize bone health post-transplant include healthy diet, weight-bearing exercise, correction of vitamin D deficiency and acidosis, electrolyte abnormalities, steroid avoidance, and consideration of recombinant human growth hormone therapy. Other drug therapies have been used in adult transplant recipients, but there is insufficient evidence for use in the pediatric population at the present time. Future therapies to be explored include anti-FGF-23 antibodies, FGF-23 receptor blockers, and treatments targeting the colonic microbiota by reduction of generation of bacterial toxins and adsorption of toxic end products that affect bone mineralization.
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Affiliation(s)
| | - Asha Moudgil
- Children National Medical Center, Washington, DC, USA
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