Incidence and predictors of fractures in children after solid organ transplantation: a 5-year prospective, population-based study

Chronic Kidney Disease-Mineral Bone Disorder (CKD-MBD) in Pediatric Kidney Transplant Recipients

Kidney transplantation remains the gold standard treatment for end-stage kidney disease (ESKD), effectively alleviating numerous comorbidities and offering a substantial survival advantage over long-term dialysis. Despite advancements in immunosuppressive regimens and improvements in graft and patient survival rates, extended patient longevity brings an accumulating burden and complexity of bone disease in this population, which often goes underrecognized. The present study reviews the pathophysiology of CKD-MBD in pediatric KTR, focusing on the progression of bone disease before and after transplantation. We aim to enhance understanding of available screening options, highlighting their advantages and limitations, to support more informed decision-making in CKD-MBD management.

Changes in bone density and microarchitecture in adolescents undergoing a first kidney transplantation: a prospective study

PURPOSE

Mineral bone disorder associated with chronic kidney disease (CKD-MBD) frequently persists after kidney transplantation (KTx), being due to pre-existing CKD-MBD, immunosuppressive therapies, and post-KTx hypophosphatemia. This study aimed to evaluate bone biomarkers and microarchitecture using high resolution peripheral quantitative computed tomography (HR-pQCT) at the time of KTx and 6 months thereafter and to compare these results with those of matched healthy controls (HC).

METHODS

This study presented the single-center subgroup of patients aged between 10 and 18 years included in the prospective "Bone Microarchitecture in the Transplant Patient" study (TRANSOS-NCT02729142). Patients undergoing a first KTx were matched (1:2) with HC from the "Vitamin D, Bones, Nutritional and Cardiovascular Status" cohort (VITADOS) on sex, pubertal stage, and age.

RESULTS

At a median (interquartile range, IQR) age of 15 [13; 16] years, 19 patients (6 girls, 7 pre-emptive KTx, 7 steroid-sparing immunosuppressive strategies) underwent a first KTx, with a median [IQR] parathyroid hormone level of 1.9 [1.4; 2.9] the upper limit of normal (ULN). Higher total and trabecular bone densities, along with superior trabecular microarchitecture, were observed at KTx compared to HC. Six months post-KTx, patients had significantly impaired trabecular parameters at the radius, while results were not significantly different at the weight-bearing tibia, neither cortical parameters at both sites. Six months post-KTx, 6 (32%) patients still present with metabolic acidosis, 10 (53%) persistent hyperparathyroidism (always < 2 ULN), and 5 (26%) elevated FGF23 levels; 11 (58%) received phosphate supplementation.

CONCLUSIONS

Bone density and microarchitecture at the time of KTx were superior compared to HC, but radial trabecular bone microarchitecture impairment observed 6 months post-KTx may reflect subtle albeit present post-KTx CKD-MBD. What is Known? • Mineral bone disorder associated with chronic kidney disease (CKD-MBD) frequently persists after kidney transplantation (KTx) and is associated with morbidity. However, biochemical parameters and dual X-ray absorptiometry (DXA) are poor predictors of the underlying bone disease. What is new? • The present study on 19 adolescent KTx recipients with adequate CKD-MBD control at the time of KTx reveals no significant bone disease compared to matched healthy controls. Microarchitecture impairment observes 6 months post-KTx may reflect subtle, albeit present, post-KTx CKD-MBD.

Prevalence and Associated Factors of Vertebral Fractures in Children with Chronic Liver Disease with and without Liver Transplantation

Purpose

To evaluate the prevalence of vertebral fracture (VF) in children with chronic liver disease (CLD) with and without liver transplantation (LT) and to determine the associated factors.

Methods

A cross-sectional study was conducted. Patients aged 3-21 years with CLD both before and after LT were enrolled in the study. Lateral thoracolumbar spine radiographs were obtained and assessed for VF using Mäkitie's method. Clinical and biochemical data were collected.

Results

We enrolled 147 patients (80 females; median age 8.8 years [interquartile range 6.0-11.8]; 110 [74.8%] in the LT group and 37 [25.2%] in the non-LT group). VF was identified in 21 patients (14.3%): 17/110 (15.5%) in the LT group and 4/37 (10.8%) in the non-LT group (p=0.54). Back pain was noted in only three patients with VF. In the univariate analysis, a height z-score below -2.0 (p=0.010), pre-LT hepatopulmonary syndrome (p=0.014), elevated serum direct and total bilirubin levels (p=0.037 and p=0.049, respectively), and vitamin D deficiency at 1-year post-LT (p=0.048) were associated with VF in the LT group. In multivariate analysis, height z-score below -2.0 was the only significant associated factor (odds ratio, 5.94; 95% confidence interval, 1.49-23.76; p=0.012) for VF. All VFs in the non-LT group were reported in males.

Conclusion

In children with CLD, VF is common before and after LT. Most patients with VF are asymptomatic. Screening for VF should be considered in patients with a height z-score below -2.0 after LT.

Predictors for pathological bone fractures in children undergoing liver transplantation: A retrospective cohort study

BACKGROUND

Hepatic osteodystrophy refers to bone disorders associated with chronic liver disease, including children undergoing liver transplantation (LT). The aim of this study was to quantify the prevalence of pathological fractures (PF) in children before and after LT and to identify associated factors for their occurrence.

METHODS

Children aged 0-18 years who underwent LT from 1/2005 to 12/2020 were included in this retrospective study. Data on patient demographics, types and anatomical locations of fracture and biological workups were extracted. Variables were assessed at 3 time points: T - 1 at the moment of listing for LT; T0 at the moment of LT and T + 1 at 1-year post-LT.

RESULTS

A total of 105 children (49 [47%] females) were included in this study. Median age at LT was 19 months (range 0-203). Twenty-two patients (21%) experienced 65 PF, 11 children before LT, 10 after LT, and 1 before and after LT. The following variables were observed as associated with PF: At T - 1, low weight and height z-scores, and delayed bone age; at T0, low weight and height z-scores, high total and conjugated bilirubin; at T + 1, persistent low height z-score. Patients in the PF-group were significantly more under calcium supplementation and/or nutritional support at T - 1, T0 and T + 1.

CONCLUSION

More than one in five children needing LT sustain a PF before or after LT. Patients with low weight and height z-scores and delayed bone age are at increased risk for PF. Nutritional support remains important, even if to date it cannot fully counteract the risks of PF.

Chronic kidney disease mineral bone disorder in childhood and young adulthood: a 'growing' understanding

Chronic kidney disease (CKD) mineral and bone disorder (MBD) comprises a triad of biochemical abnormalities (of calcium, phosphate, parathyroid hormone and vitamin D), bone abnormalities (turnover, mineralization and growth) and extra-skeletal calcification. Mineral dysregulation leads to bone demineralization causing bone pain and an increased fracture risk compared to healthy peers. Vascular calcification, with hydroxyapatite deposition in the vessel wall, is a part of the CKD-MBD spectrum and, in turn, leads to vascular stiffness, left ventricular hypertrophy and a very high cardiovascular mortality risk. While the growing bone requires calcium, excess calcium can deposit in the vessels, such that the intake of calcium, calcium- containing medications and high calcium dialysate need to be carefully regulated. Normal physiological bone mineralization continues into the third decade of life, many years beyond the rapid growth in childhood and adolescence, implying that skeletal calcium requirements are much higher in younger people compared to the elderly. Much of the research into the link between bone (de)mineralization and vascular calcification in CKD has been performed in older adults and these data must not be extrapolated to children or younger adults. In this article, we explore the physiological changes in bone turnover and mineralization in children and young adults, the pathophysiology of mineral bone disease in CKD and a potential link between bone demineralization and vascular calcification.

Bone health in children undergoing solid organ transplantation

PURPOSE OF REVIEW

Pediatric solid organ transplant recipients are a unique and growing patient population who are at risk for metabolic bone disease both before and after transplantation.

RECENT FINDINGS

The odds of sustaining a fracture in adulthood are significantly higher if an individual has sustained at least one childhood fracture, therefore, close monitoring before and after transplant is essential. Emerging data in patients with chronic kidney disease mineral and bone disorder (CKD-MBD) and hepatic osteodystrophy highlights the role of fibroblast growth factor 23 in the pathogenesis of metabolic bone disease in these conditions. While dual X-ray absorptiometry (DXA) is the most widely used imaging modality for assessment of bone mass in children, quantitative computer tomography (QCT) is an emerging modality, especially for patients with glucocorticoid-induced osteoporosis.

SUMMARY

Solid organ transplantation improves organ function and quality of life; however, bone mineral density can decline following transplantation, particularly during the first three to six months. Immunosuppressive medications, including glucocorticoids, are a major contributing factor. Following transplant, treatment should be tailored to achieve mineral homeostasis, correct nutritional deficiencies, and improve physical conditioning. In summary, early identification and treatment of metabolic bone disease can improve the bone health status of pediatric transplant recipients as they enter adulthood.

VIDEO ABSTRACT

http://links.lww.com/MOP/A71.

Vitamin D Deficiency in Chronic Childhood Disorders: Importance of Screening and Prevention

Vitamin D plays a vital role in regulating calcium and phosphate metabolism and maintaining bone health. A state of prolonged or profound vitamin D deficiency (VDD) can result in rickets in children and osteomalacia in children and adults. Recent studies have demonstrated the pleiotropic action of vitamin D and identified its effects on multiple biological processes in addition to bone health. VDD is more prevalent in chronic childhood conditions such as long-standing systemic illnesses affecting the renal, liver, gastrointestinal, skin, neurologic and musculoskeletal systems. VDD superimposed on the underlying disease process and treatments that can adversely affect bone turnover can all add to the disease burden in these groups of children. The current review outlines the causes and mechanisms underlying poor bone health in certain groups of children and young people with chronic diseases with an emphasis on the proactive screening and treatment of VDD.

International Pediatric Transplant Association (IPTA) position statement supporting prioritizing pediatric recipients for deceased donor organ allocation

A position statement of the International Pediatric Transplant Association endorsing prioritizing pediatric recipients for deceased donor organ allocation, examining the key ethical arguments that serve as the foundation for that position, and making specific policy recommendations to support prioritizing pediatric recipients for deceased donor organ allocation globally.

Bone demineralization in a cohort of Egyptian pediatric liver transplant recipients: Single center pilot study

Liver transplantation (LT) is the definitive treatment of end-stage liver disease. The long-term survival following LT spurred more interest in improving the quality of life of patients. This was a cohort study that included 23 pediatric liver transplant recipients who underwent LT due to hereditary or metabolic liver diseases. Bone health assessment was performed at their last follow up clinically (anthropometric measures), biochemically and radiologically (Dual Energy X-ray Absorptiometry [DEXA] scans). Poor bone health was defined as z-score <-1. Mean age at LT was 5.77 years (standard deviation [SD] 3.64) and 43% were males. Biliary atresia was the most common cause of end stage liver disease (35%). Mean age at follow up was 14 years (SD 5.48) and mean follow up was 8 years (SD 4.12 years). Eleven patients (48%) had poor bone health (osteopenia 22% and osteoporosis 26%). On univariate analysis, being on steroids at last follow up (odds ratio [OR] 13.2, 95% confidence interval [CI] 1.23-140.67, P = .03), weight at last follow up (OR 0.45, 95% CI 0.20-0.99, P = .04), platelets at last follow up (OR 0.98, 95% CI 0.96-s0.99, P = .02), hemoglobin at last follow up (OR 0.33, 95% CI 0.12-0.89, P = .03) were significantly associated with poor bone health. None of the variables were significant on multivariate analysis. At most recent follow up, 48% of patients demonstrated poor bone health by DEXA scans. More studies are required to evaluate predictors of poor bone health after LT in children.

Clinical practice guidelines for optimizing bone health in Korean children and adolescents

The Committee on Pediatric Bone Health of the Korean Society of Pediatric Endocrinology has newly developed evidence-based clinical practice guidelines for optimizing bone health in Korean children and adolescents. These guidelines present recommendations based on the Grading of Recommendations, which includes the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. These guidelines include processes of bone acquisition, definition, and evaluation of low bone mineral density (BMD), causes of osteoporosis, methods for optimizing bone health, and pharmacological treatments for enhancing BMD in children and adolescents. While these guidelines provide current evidence-based recommendations, further research is required to strengthen these guidelines.

Promoting bone health in children and adolescents following solid organ transplantation

Solid organ transplantation in children and adolescents provides many benefits through improving critical organ function, including better growth, development, cardiovascular status, and quality of life. Unfortunately, bone status may be adversely affected even when overall status is improving, due to issues with pre-existing bone disease as well as medications and nutritional challenges inherent post-transplantation. For all children and adolescents, bone status entering adulthood is a critical determinant of bone health through adulthood. The overall health and bone status of transplant recipients benefits from attention to regular physical activity, good nutrition, adequate calcium, phosphorous, magnesium and vitamin D intake and avoidance/minimization of soda, extra sodium, and obesity. Many immunosuppressive agents, especially glucocorticoids, can adversely affect bone function and development. Minimizing exposure to "bone-toxic" medications is an important part of promoting bone health in children post-transplantation. Existing guidelines detail how regular monitoring of bone status and biochemical markers can help detect bone abnormalities early and facilitate valuable bone-directed interventions. Attention to calcium and vitamin D supplementation, as well as tapering and withdrawing glucocorticoids as early as possible after transplant, can provide best bone outcomes for these children. Dual-energy X-ray absorptiometry can be useful to detect abnormal bone mass and fracture risk in this population and newer bone assessment methods are being evaluated in children at risk for poor bone outcomes. Newer bone therapies being explored in adults with transplants, particularly bisphosphonates and the RANKL inhibitor denosumab, may offer promise for children with low bone mass post-transplantation.

Practical Guidance for Prevention and Management of Glucocorticoid-Induced Osteoporosis for the Allergist/Immunologist

Osteoporosis is a silent disorder with dire consequences, and glucocorticoid use remains the most common iatrogenic cause illustrated by the fact that 30% to 50% of subjects on such long-term therapy experience fractures (Oimomi M, Nakamichi T, Ohara T, Sakai M, Igaki N, Hata F, et al. Fructose-related glycation. Diabetes Res Clin Pract 1989;7:137-9; Reid IR. Glucocorticoid osteoporosis--mechanisms and management. Eur J Endocrinol 1997;137:209-17). By directly affecting bone quality while actively used, glucocorticoids increase the risk of fracture that is independent of a subject's bone density status at the time (Weinstein RS. True strength. J Bone Miner Res 2000;15:621-5). A large number of subjects seen in an allergy and immunology clinic have asthma, chronic rhinosinusitis, or other chronic inflammatory diseases, necessitating the use of these medications and placing them at higher risk for this disease. Data on the effects of both oral and inhaled glucocorticoids on fracture risk are presented. This review concretizes the importance of osteoporosis, its pathophysiology, and provides practical guidelines to prevent and treat it. Management recommendations are tailored to 2 different age groups. The first group consists of children, adolescents, and adults 40 years or younger with a focus on attaining peak bone mass. The second group consists of adults 40 years or older where the use of imaging modalities and Fracture Risk Assessment Tool scores helps triage subjects into fracture risk categories. Those at moderate to high risk require bone-sparing medications. Universal preventive measures for both groups are reviewed. Complicated and severe cases may need additional expertise by an endocrinologist or rheumatologist.

CKD-MBD post kidney transplantation

Complications of chronic kidney disease-associated mineral and bone disorders (CKD-MBD) are frequently observed in pediatric kidney transplant recipients and are associated with high morbidity, including growth failure, leg deformities, bone pain, fractures, osteonecrosis, and vascular calcification. Post-transplant CKD-MBD is mainly due to preexisting renal osteodystrophy and cardiovascular changes at the time of transplantation, glucocorticoid treatment, and reduced graft function. In addition, persistent elevated levels of parathyroid hormone (PTH) and fibroblast growth factor 23 may cause hypophosphatemia, resulting in impaired bone mineralization. Patient monitoring should include assessment of growth, leg deformities, and serum levels of calcium, phosphate, magnesium, alkaline phosphatase, 25-hydroxyvitamin D, and PTH. Therapy should primarily focus on regular physical activity, preservation of transplant function, and steroid-sparing immunosuppressive protocols. In addition, adequate monitoring and treatment of vitamin D and mineral metabolism including vitamin D supplementation, oral phosphate, and/or magnesium supplementation, in case of persistent hypophosphatemia/hypomagnesemia, and treatment with active vitamin D in cases of persistent secondary hyperparathyroidism. The latter should be done using the minimum PTH-suppressive dosages aiming at the recommended CKD stage-dependent PTH target range. Finally, treatment with recombinant human growth hormone should be considered in patients lacking catch-up growth within the first year after transplantation.

Glucocorticoid-Induced Osteoporosis: Why Kids Are Different

Glucocorticoids (GC) are an important risk factor for bone fragility in children with serious illnesses, largely due to their direct adverse effects on skeletal metabolism. To better appreciate the natural history of fractures in this setting, over a decade ago the Canadian STeroid-associated Osteoporosis in the Pediatric Population ("STOPP") Consortium launched a 6 year, multi-center observational cohort study in GC-treated children. This study unveiled numerous key clinical-biological principles about GC-induced osteoporosis (GIO), many of which are unique to the growing skeleton. This was important, because most GIO recommendations to date have been guided by adult studies, and therefore do not acknowledge the pediatric-specific principles that inform monitoring, diagnosis and treatment strategies in the young. Some of the most informative observations from the STOPP study were that vertebral fractures are the hallmark of pediatric GIO, they occur early in the GC treatment course, and they are frequently asymptomatic (thereby undetected in the absence of routine monitoring). At the same time, some children have the unique, growth-mediated ability to restore normal vertebral body dimensions following vertebral fractures. This is an important index of recovery, since spontaneous vertebral body reshaping may preclude the need for osteoporosis therapy. Furthermore, we now better understand that children with poor growth, older children with less residual growth potential, and children with ongoing bone health threats have less potential for vertebral body reshaping following spine fractures, which can result in permanent vertebral deformity if treatment is not initiated in a timely fashion. Therefore, pediatric GIO management is now predicated upon early identification of vertebral fractures in those at risk, and timely intervention when there is limited potential for spontaneous recovery. A single, low-trauma long bone fracture can also signal an osteoporotic event, and a need for treatment. Intravenous bisphosphonates are currently the recommended therapy for pediatric GC-induced bone fragility, typically prescribed to children with limited potential for medication-unassisted recovery. It is recognized, however, that even early identification of bone fragility, combined with timely introduction of intravenous bisphosphonate therapy, may not completely rescue the osteoporosis in those with the most aggressive forms, opening the door to novel strategies.

Assessing bone mineralisation in children with chronic kidney disease: what clinical and research tools are available?

Mineral and bone disorder in chronic kidney disease (CKD-MBD) is a triad of biochemical imbalances of calcium, phosphate, parathyroid hormone and vitamin D, bone abnormalities and soft tissue calcification. Maintaining optimal bone health in children with CKD is important to prevent long-term complications, such as fractures, to optimise growth and possibly also to prevent extra-osseous calcification, especially vascular calcification. In this review, we discuss normal bone mineralisation, the pathophysiology of dysregulated homeostasis leading to mineralisation defects in CKD and its clinical consequences. Bone mineralisation is best assessed on bone histology and histomorphometry, but given the rarity with which this is performed, we present an overview of the tools available to clinicians to assess bone mineral density, including serum biomarkers and imaging such as dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. We discuss key studies that have used these techniques, their advantages and disadvantages in childhood CKD and their relationship to biomarkers and bone histomorphometry. Finally, we present recommendations from relevant guidelines-Kidney Disease Improving Global Outcomes and the International Society of Clinical Densitometry-on the use of imaging, biomarkers and bone biopsy in assessing bone mineral density. Given low-level evidence from most paediatric studies, bone imaging and histology remain largely research tools, and current clinical management is guided by serum calcium, phosphate, PTH, vitamin D and alkaline phosphatase levels only.

Good long-term renal graft survival and low incidence of cardiac pathology in adults after short dialysis period and renal transplantation in early childhood - a cohort study

Over the past 30 years, there has been an improvement in both patient and graft survival after pediatric renal transplantation (RTX). Despite this success, these patients still carry an elevated risk for untimely death, partly through premature aging of the vasculature. The aim of this study was thus to investigate the long-term outcome of individuals with RTX in childhood, as well as to explore the cardiovascular health of these adults more than a decade later. We studied 131 individuals who had undergone a RTX between the years 1979 and 2005. Furthermore, left ventricular hypertrophy (LVH), coronary artery calcifications (CAC), and related metabolic factors were investigated in a cross-sectional study including 52 individuals as part of the initial cohort. The mortality rate (n = 131) was 12.2%. The median estimated graft survival was 17.5 years (95% CI 13.6-21.3), being significantly better in children transplanted below the age of 5 years (18.6 vs. 14.3 years, P < 0.01) compared with older ones. CAC were found in 9.8% and LVH in 13% of the patients. Those with cardiac calcifications had longer dialysis vintage and higher values of parathyroid hormone (PTH) during dialysis. Left ventricular mass correlated positively with systolic blood pressure, PTH, and phosphate measured at the time of the study.

Growth, body composition, and bone density following pediatric liver transplantation

Patients transplanted for cholestatic liver disease are often significantly fat-soluble vitamin deficient and malnourished pretransplant, with significant corticosteroid exposure post-transplant, with increasing evidence of obesity and metabolic syndrome post-LT. Our study aimed to assess growth, body composition, and BMD in patients post-pediatric LT. Body composition and bone densitometry scans were performed on 21 patients. Pre- and post-transplant anthropometric data were analyzed. Bone health was assessed using serum ALP, calcium, phosphate, and procollagen-1-N-peptide levels. Median ages at transplant and at this assessment were 2.7 and 10.6 years, respectively. Physiological markers of bone health, median z-scores for total body, and lumbar spine aBMD were normal. Bone area was normal for height and BMAD at L3 was normal for age, indicating, respectively, normal cortical and trabecular bone accrual. Median z-scores for weight, height, and BMI were 0.6, -0.9, 1.8 and 0.6, 0.1, 0.8 pre- and post-transplant, respectively. Total body fat percentages measured on 21 body composition scans revealed 2 underweight, 7 normal, 6 overweight, and 6 obese. Bone mass is preserved following pediatric LT with good catch-up height. About 52% of patients were either overweight/obese post-transplant, potentially placing them at an increased risk of metabolic syndrome and its sequelae in later life. BMI alone is a poor indicator of nutritional status post-transplant.

A 3-year longitudinal study of skeletal effects and growth in children after kidney transplantation

This prospective study investigated growth and skeletal development for 3 years after kidney transplantation in pediatric patients, 3.4-15.0 years of age. Growth, BMD, bone resorption markers (CTX and TRACP5b), bone formation markers (PINP, ALP, and osteocalcin), PTH, and vitamin D were assessed at start, 3, 12, and 36 months after transplantation. Median GFR was 63 (range 37-96) mL/min/1.73 m2 after 3 years. The median height SDS increased from -1.7 to -1.1, and median BMI SDS increased from -0.1 to 0.6 over 3 years, which shows that transplantation had a favorable outcome on growth. Fat mass increased after transplantation at all time points, whereas lean mass increased after 1 year and 3 years. Total BMC increased at all time points. No changes were observed for total BMD. Bone resorption markers decreased initially after 3 months and remained stable throughout the study, whereas the bone formation markers decreased initially, but successively increased over the study period. In conclusion, this study demonstrates that height SDS and BMI SDS increased, along with the increased formation markers that reveal a positive bone acquisition after kidney transplantation, which was reflected by the significant increase in total body BMC.

Pediatric dual-energy X-ray absorptiometry in clinical practice: What the clinicians need to know

The importance of childhood and adolescence for bone development and mineral accrual is increasingly accepted, leading to a need of suitable methods for monitoring bone health even in pediatric setting. Among the several different imaging methods available for clinical measurement of bone mineral density (BMD) in children, dual-energy X-ray absorptiometry (DXA) is the most widely available and commonly used due to its reproducibility, negligible radiation dose and reliable pediatric reference data. Nevertheless, DXA in children has some technical specific features that should be known by those physicians who interpret and report this examination. We provide recommendations for optimal DXA scan reporting in pediatric setting, including indications, skeletal sites to be examined, parameters to be measured, timing of follow-up BMD measurements. Adequate report and analysis of DXA examinations are essential to prevent over- and underdiagnosis of bone mineral impairment in pediatric patients. In conclusion, a complete and exhaustive DXA report in children and adolescents is mandatory for an accurate diagnosis and a precise monitoring of pediatric bone status.

Bone Mineral Density of Very Long-term Survivors After Childhood Liver Transplantation

OBJECTIVES

Liver transplant patients are at risk of osteopenia and fractures but limited information is available in long-term survivors after childhood transplantation. This study aimed to assess bone mineral density (BMD) of very long-term, >5 years, survivors after liver transplantation in childhood.

METHODS

Patients aged <18 years at transplant, having survived >5 years after transplant were potentially eligible but only those with ongoing review in our state were included. Dual-energy x-ray absorptiometry (DXA) was used to measure BMD. Patients aged <20 years had lumbar spine (LS) and total body (TB) measurements whereas those aged 20 years or more had LS and femoral neck but not TB. BMD z-scores for LS and TB, if available, were used in this study. BMD z-score ≤-2.0 was considered reduced. Pre-pubertal children had radiologic bone age assessment.

RESULTS

Forty-two patients, 17 boys, participated of whom 64% had biliary atresia. Median age at transplant was 2.22 (range 0.38-14.25) years; time since transplant 10.10 (5.01-25.98) years; and age at DXA 14.64 (6.59-38.07) years. Mean BMD z-scores were LS -0.15 ± 1.07, and TB -0.76 ± 1.14, with no sex difference noted. Four (9.5%) patients had reduced LS BMD, and although ongoing steroid use was more frequent in these patients, other comorbidities were likely important. Age at transplant, time since transplant, height, weight, and body mass index at DXA did not predict LS BMD. Pathologic fractures occurred in 2 of 42 (5%) patients; all within 18 months of transplant.

CONCLUSIONS

Very long-term survivors after childhood liver transplant have LS BMD within the normal range.

Bone mineral density is compromised in very long-term survivors of irradiated childhood brain tumor

INTRODUCTION

The increase in the number of childhood brain tumor survivors warrants detailed research to increase our knowledge regarding the possible physical and psychosocial adverse outcomes of tumor and tumor therapy. The aim of this study was to evaluate the current bone health by measuring the bone mineral density (BMD) in irradiated, adult long-term survivors of childhood brain tumors.

MATERIAL AND METHODS

We studied a national cohort of 74 adult survivors of childhood brain tumors treated with irradiation in Finland between 1970 and 2008. Dual X-ray absorptiometry (DXA) was performed for the femoral necks, total hips, and lumbar spine. Laboratory tests were conducted for evaluating the pituitary, thyroid, and gonadal functions. The participants were interviewed, examined clinically, and the disease and treatment related data were retrieved from the patient files.

RESULTS

One fourth of the patients (23.6%) had sex- and age-normalized z-scores below the expected range for age (z-score ≤ -2.0). Mean BMD scores were decreased in all the DXA measurement sites. Male sex was associated with low BMD (p < .05), while body mass index (BMI) had a significant positive association with BMD (p < .01). Mode of irradiation (with or without spinal irradiation) or inclusion of chemotherapy in the treatment did not affect BMD significantly. However, patients with a ventriculoperitoneal shunt had lower BMD than those without a shunt (p < .05). Follicle stimulating hormone (FSH) and luteinizing hormone (LH) were negatively associated with BMD in women (p < .05). However, a higher cumulative dose of glucocorticoids during treatment was not associated with lower BMD, while low BMD was significantly associated with previous fractures in long bones.

DISCUSSION

Low BMD should be taken in consideration in treatment of irradiated childhood brain tumor survivors especially in those with previous fractures in long bones.

Skeletal manifestations of renal disease in childhood

PURPOSE OF REVIEW

This review summarizes recent findings on musculoskeletal health in three chronic renal conditions of childhood: chronic kidney disease stages 2-5D, nephrotic syndrome, and urolithiasis. Findings with important clinical implications warranting further investigation are highlighted.

RECENT FINDINGS

Recent cohort studies have demonstrated a high burden of fracture and progressive deficits of cortical bone in children with chronic kidney disease. Lower cortical density is associated with incident fracture and may be an important therapeutic target. Parathyroid hormone and calcium are independent correlates of cortical density, and modifiable factors for fracture include parathyroid hormone and phosphate binder use. Children with nephrotic syndrome, even with normal renal function, have evidence of abnormal bone metabolism and structure, and vitamin D deficiency may be an important modifiable risk factor in this population. Urolithiasis has been associated with reduced bone mineral density and is increasingly common in children and adolescents. Population-based data found a significantly increased risk of fracture in adolescent males and young women.

SUMMARY

Recent findings substantiate concern regarding the particular vulnerability of the growing skeleton to chronic renal disease. Studies are needed to determine how to optimize assessment and management of bone health in children with these conditions, particularly in terms of calcium and vitamin D requirements, with the goal of improving childhood bone accrual for lifelong fracture prevention.

Osteoporosis in Children with Chronic Illnesses: Diagnosis, Monitoring, and Treatment

PURPOSE OF REVIEW

Osteoporosis is an under-recognized complication of chronic illness in childhood. This review will summarize recent literature addressing the risk factors, evaluation, and treatment for early bone fragility.

RECENT FINDINGS

Criteria for the diagnosis of pediatric osteoporosis include the presence of low trauma vertebral fractures alone or the combination of low bone mineral density and several long bone fractures. Monitoring for bone health may include screening for vertebral fractures that are common but often asymptomatic. Pharmacologic agents should be offered to those with fragility fractures especially when spontaneous recovery is unlikely. Controversies persist about the optimal bisphosphonate agent, dose, and duration. Newer osteoporosis drugs have not yet been adequately tested in pediatrics, though clinical trials are underway. The prevalence of osteoporosis is increased in children with chronic illness. To reduce the frequency of fragility fractures requires increased attention to risk factors, early intervention, and additional research to optimize therapy and potentially prevent their occurrence.

Abnormally High and Heterogeneous Bone Matrix Mineralization After Childhood Solid Organ Transplantation: A Complex Pathology of Low Bone Turnover and Local Defects in Mineralization

Chronic renal, liver, and heart failure in children associates with multiple skeletal complications. Increased fracture incidence often persists after transplantation and could be related to alterations in bone material properties. In the present cohort study we evaluated bone mineralization density distribution (BMDD) by quantitative backscattered electron imaging (qBEI) in 23 pediatric solid organ allograft recipients with suspected osteoporosis. We measured BMDD in the entire cross-sectional area of transiliac bone biopsies obtained from kidney (n = 9), liver (n = 9), and heart (n = 5) transplant recipients (aged 7.6 to 19.7 years; 6.0 ± 5.6 years posttransplantation, patients with a history of clinical fractures: n = 14). The BMDD findings were compared with age-appropriate references and with a previously presented cohort of children with chronic kidney disease on dialysis (CKD5D, n = 18). Furthermore, we related the BMDD parameters with patients' clinical and bone histomorphometric outcomes. Compared to healthy children, qBEI results for cancellous and cortical bone in transplant recipients revealed an increase in the most frequently occurring calcium concentration (+2.9%, p = 0.001; +3.5%, p = 0.014), in the portion of fully mineralized bone (fivefold; 10-fold, both p < 0.0001) and in heterogeneity of mineralization (+26,5% and +27.8%, both p < 0.0001), respectively. Moreover, the BMDD parameters were nonsignificantly distinct from CKD5D cohort except that the heterogeneity in mineralization was higher posttransplantation. There was a strong inverse correlation between the average calcium content of the bone matrix and patients' biochemical ALP levels, histomorphometric indices of bone formation and resorption. The abnormally high bone matrix mineralization in transplant recipients, consistent with serum and histomorphometric outcomes, suggests a history of low bone turnover with accumulation of fully mineralized bone packets. Additionally, the increased heterogeneity of mineralization suggests local alterations in mineralization kinetics, which may be linked to dysfunctional osteocytes that were recently shown to accumulate within the bone matrix during organ failure and concomitant glucocorticoid and immunosuppressive medication. © 2017 American Society for Bone and Mineral Research.

The management of osteoporosis in children

This article reviews the manifestations and risk factors associated with osteoporosis in childhood, the definition of osteoporosis and recommendations for monitoring and prevention. As well, this article discusses when a child should be considered a candidate for osteoporosis therapy, which agents should be prescribed, duration of therapy and side effects. There has been significant progress in our understanding of risk factors and the natural history of osteoporosis in children over the past number of years. This knowledge has fostered the development of logical approaches to the diagnosis, monitoring, and optimal timing of osteoporosis intervention in this setting. Current management strategies are predicated upon monitoring at-risk children to identify and then treat earlier rather than later signs of osteoporosis in those with limited potential for spontaneous recovery. On the other hand, trials addressing the prevention of the first-ever fracture are still needed for children who have both a high likelihood of developing fractures and less potential for recovery. This review focuses on the evidence that shapes the current approach to diagnosis, monitoring, and treatment of osteoporosis in childhood, with emphasis on the key pediatric-specific biological principles that are pivotal to the overall approach and on the main questions with which clinicians struggle on a daily basis. The scope of this article is to review the manifestations of and risk factors for primary and secondary osteoporosis in children, to discuss the definition of pediatric osteoporosis, and to summarize recommendations for monitoring and prevention of bone fragility. As well, this article reviews when a child is a candidate for osteoporosis therapy, which agents and doses should be prescribed, the duration of therapy, how the response to therapy is adjudicated, and the short- and long-term side effects. With this information, the bone health clinician will be poised to diagnose osteoporosis in children and to identify when children need osteoporosis therapy and the clinical outcomes that gauge efficacy and safety of treatment.

Renal transplantation in infants

Renal transplantation (RTx) has become an accepted mode of therapy in infants with severe renal failure. The major indications are structural abnormalities of the urinary tract, congenital nephrotic syndrome, polycystic diseases, and neonatal kidney injury. Assessment of these infants needs expertise and time as well as active treatment before RTx to ensure optimal growth and development, and to avoid complications that could lead to permanent neurological defects. RTx can be performed already in infants weighing around 5 kg, but most operations occur in infants with a weight of 10 kg or more. Perioperative management focuses on adequate perfusion of the allograft and avoidance of thrombotic and other surgical complications. Important long-term issues include rejections, infections, graft function, growth, bone health, metabolic problems, neurocognitive development, adherence to medication, pubertal maturation, and quality of life. The overall outcome of infant RTx has dramatically improved, with long-term patient and graft survivals of over 90 and 80 %, respectively.

Post-Renal Transplantation Bone Health in Children Evaluated by Means of Quantitative Ultrasound and Densitometry

BACKGROUND

Patients with end-stage renal disease develop bone mineral disease, which is not always resolved after a successful renal transplantation; moreover, some of the immunosuppressants used to prevent graft rejection may affect bone health. The aim of this study was to evaluate bone health in post-renal transplantation children with the use of quantitative ultrasound (QUS) and dual-energy X-ray absorptiometry (DXA).

METHODS

A descriptive study was performed in children >3 months after renal transplantation and with stable function of graft. Radial QUS and DXA (lumbar spine and total body less head (TBLH) were performed on the same day.

RESULTS

A total of 35 patients were included. Mean age was 13.9 ± 3.9 years. Ten subjects had total bone density score <2 (28.5%), 4 a lumbar spine (L1-L4) Z-score of <2 (11.4%) as well as TBLH <2, and 6 subjects had a radial QUS Z-score of <2 (17.1%), and only 2 of them had concomitant Z-score <2 with the use of DXA. There was a positive non-significant correlation between TBLH and radial QUS Z-scores (Pearson r = 0.317; P = .016) and a positive significant correlation of DXA lumbar spine and radial QUS Z-scores (Pearson r = 0.452; P = .014).

CONCLUSIONS

Despite a good correlation between TBLH and QUS Z-scores, there are subjects that can be considered normal by QUS and have osteopenia by TBLH DXA and vice versa; this could be due to the different bone areas evaluated.

Proceedings of the 2015 Santa Fe Bone Symposium: Clinical Applications of Scientific Advances in Osteoporosis and Metabolic Bone Disease

The 2015 Santa Fe Bone Symposium was a venue for healthcare professionals and clinical researchers to present and discuss the clinical relevance of recent advances in the science of skeletal disorders, with a focus on osteoporosis and metabolic bone disease. Symposium topics included new developments in the translation of basic bone science to improved patient care, osteoporosis treatment duration, pediatric bone disease, update of fracture risk assessment, cancer treatment-related bone loss, fracture liaison services, a review of the most significant studies of the past year, and the use of telementoring with Bone Health Extension for Community Healthcare Outcomes, a force multiplier to improve the care of osteoporosis in underserved communities.

Long-term effects of paediatric kidney transplantation

Renal transplantation in paediatric patients usually provides excellent short-term and medium-term results. Early diagnosis of chronic kidney disease and active therapy of end-stage renal disease before and after transplantation enables the majority of children to grow and develop normally. The adverse effects of immunosuppressive medication and reduced graft function might, however, hamper long-term outcomes in these patients and can lead to metabolic complications, cardiovascular disease, reduced bone health, and malignancies. The neurocognitive development and quality of life of paediatric transplant recipients largely depend on the primary diagnosis and on graft function. Poor adherence to immunosuppression is an important risk factor for graft loss in adolescents, and controlled transition to adult care is of utmost importance to ensure a continued normal life. In this Review, we discuss the outcomes and long-term effects of renal transplantation in paediatric recipients, including consequences on growth, development, bone, metabolic, and cardiovascular disorders. We discuss the key problems in the care of paediatric renal transplant recipients and the remaining challenges that should be the focus of future research.

Altered Osteocyte-Specific Protein Expression in Bone after Childhood Solid Organ Transplantation

Background

Bone fragility is common post solid organ transplantation but little is known about bone pathology on a tissue level. Abnormal osteocytic protein expression has been linked to compromised bone health in chronic kidney disease (CKD) and immunosuppressant medications may impact osteocyte function.

Methods

Transiliac bone biopsies were obtained from 22 pediatric solid organ allograft recipients (average age 15.6 years) an average of 6.3 ± 1.2 years after transplantation and from 12 pediatric pre-dialysis CKD patients (average age 13.2 years). Histomorphometry and immunohistochemistry for FGF23, DMP1, sclerostin, and osteopontin were performed on all biopsies.

Results

FGF23 and sclerostin were increased in transplant recipients relative to non-transplant CKD, regardless of the type of allograft received and despite, in the case of liver and heart recipients, a higher GFR. Bone DMP1 expression was higher in liver or heart than in kidney recipients, concomitant with higher serum phosphate values. Osteopontin expression was higher in CKD than in transplant recipients (p<0.01). Bone FGF23 and sclerostin correlated directly (r = 0.38, p<0.05); bone FGF23 expression and osteoid thickness correlated inversely (r = - 0.46, p<0.01).

Conclusions

Solid-organ transplantation is associated with increased FGF23 and sclerostin expression. The contribution of these findings to compromised bone health post transplantation warrants further evaluation.

The Child with Multiple Fractures, What Next?

Fractures are common during childhood; however, they can also be the presenting symptom of primary or secondary causes of bone fragility. The challenge is to identify those children who warrant further investigation. In children who present with multiple fractures that are not commonly associated with mild to moderate trauma or whose fracture count is greater than what is typically seen for their age, an initial evaluation, including history, physical examination, biochemistry, and spinal radiography, should be performed. In children with bone pain or evidence of more significant bone fragility, referral for specialist evaluation and consideration of pharmacologic treatment may be warranted.

Fracture Burden and Risk Factors in Childhood CKD: Results from the CKiD Cohort Study

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.

Comparison of bone mineral density changes in pediatric thalassemic patients with and without hematopoietic stem cell transplant

OBJECTIVES

Beta thalassemia major is a genetic hemoglobin disorder that affects bone density. The disease leads to deteriorating bone structure but can be treated with hematopoietic stem cell transplant. We aimed to assess bone mineral density changes in pediatric beta thalassemia major patients who had undergone a hematopoietic stem cell transplant compared with similarly affected patients who had not undergone a hematopoietic stem cell transplant.

MATERIALS AND METHODS

Forty beta thalassemia major patients, 20 transplant and 20 nontransplant, younger than 16 years of age were enrolled. The mean age of transplant patients was 8.15 years and nontransplant patients was 9.5 years (P = .242). The female:male ratio was 1:1 in both groups. None of the patients reached puberty during this study. Bone mineral density was evaluated in transplant patients before and 1 year after hematopoietic stem cell transplant. Bone mineral density of nontransplant patients also was evaluated 1 year after their initial bone mineral density test. A Norland XR-46 densitometer was used to make all bone mineral density measurements. None of the patients had a z score < -2.

RESULTS

Mean bone mineral density changes in the femur and spine during this study were 0.008 ± 0.075 g/cm2 and 0.048 ± 0.045 g/cm2 in transplant patients and 0.045 ± 0.072 g/cm2 and 0.036 ± 0.058 g/cm2 in nontransplant patients. No significant differences between bone mineral density changes in transplant and nontransplant patients were detected during the study.

CONCLUSIONS

No significant effects on bone mineral density were detected in hematopoietic stem cell transplant pediatric beta thalassemia major patients compared with similarly affected nontransplant patients. Studies of longer duration may be required to identify significant changes in bone mineral density in hematopoietic stem cell transplant patients.

Pediatric solid organ transplantation and osteoporosis: a descriptive study on bone histomorphometric findings

BACKGROUND

Organ transplantation may lead to secondary osteoporosis in children. This study characterized bone histomorphometric findings in pediatric solid organ transplant recipients who were assessed for suspected secondary osteoporosis.

METHODS

Iliac crest biopsies were obtained from 19 children (7.6-18.8 years, 11 male) who had undergone kidney (n = 6), liver (n = 9), or heart (n = 4) transplantation a median 4.6 years (range 0.6-16.3 years) earlier. All patients had received oral glucocorticoids at the time of the biopsy.

RESULTS

Of the 19 patients, 21 % had sustained peripheral fractures and 58 % vertebral compression fractures. Nine children (47 %) had a lumbar spine BMD Z-score below -2.0. Histomorphometric analyses showed low trabecular bone volume (< -1.0 SD) in 6 children (32 %) and decreased trabecular thickness in 14 children (74 %). Seven children (37 %) had high bone turnover at biopsy, and low turnover was found in 6 children (32 %), 1 of whom had adynamic bone disease.

CONCLUSIONS

There was a great heterogeneity in the histological findings in different transplant groups, and the results were unpredictable using non-invasive methods. The observed changes in bone quality (i.e. abnormal turnover rate, thin trabeculae) rather than the actual loss of trabecular bone, might explain the increased fracture risk in pediatric solid organ transplant recipients.

Bone health in children and adolescents with chronic diseases that may affect the skeleton: the 2013 ISCD Pediatric Official Positions

The aim of this Task Force was to review the use of dual-energy X-ray absorptiometry (DXA) in children and adolescents with underlying chronic diseases that pose risk factors for compromised bone health, such as inflammation, glucocorticoid therapy, or decreased mobility. The Task Force systematically analyzed more than 270 studies, with an emphasis on those published in the interval since the original 2007 Position Statements. Important developments over this period included prospective cohort studies demonstrating that DXA measures of areal bone mineral density (aBMD) predicted incident fractures and the development of robust reference data and strategies to adjust for bone size in children with growth impairment. In this report, we summarize the current literature on the relationship between DXA-based aBMD and both fracture (vertebral and non-vertebral) outcomes and non-fracture risk factors (e.g., disease characteristics, ambulatory status, and glucocorticoid exposure) in children with chronic illnesses. Most publications described the aBMD profile of children with underlying diseases, as well as the cross-sectional or longitudinal relationship between aBMD and clinically relevant non-fracture outcomes. Studies that addressed the relationship between aBMD and prevalent or incident fractures in children with chronic illnesses are now emerging. In view of these updated data, this report provides guidelines for the use of DXA-based aBMD in this setting. The initial recommendation that DXA is part of a comprehensive skeletal healthy assessment in patients with increased risk of fracture is unchanged. Although the prior guidelines recommended DXA assessment in children with chronic diseases at the time of clinical presentation with ongoing monitoring, this revised Position Statement focuses on the performance of DXA when the patient may benefit from interventions to decrease their elevated risk of a clinically significant fracture and when the DXA results will influence that management.

Optimization of Bone Health in Children before and after Renal Transplantation: Current Perspectives and Future Directions

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.

Changes in DXA and quantitative CT measures of musculoskeletal outcomes following pediatric renal transplantation

This prospective study evaluated changes in dual energy X-ray absorptiometry (DXA) whole body bone mineral content (WB-BMC) and spine areal bone mineral density (spine-BMD), and tibia quantitative computed tomography (QCT) trabecular and cortical volumetric BMD and cortical area in 56 children over 12 months following renal transplantation. At transplant, spine-BMD Z-scores were greater in younger recipients (<13 years), versus 898 reference participants (p < 0.001). In multivariate models, greater decreases in spine-BMD Z-scores were associated with greater glucocorticoid dose (p < 0.001) and declines in parathyroid hormone levels (p = 0.008). Changes in DXA spine-BMD and QCT trabecular BMD were correlated (r = 0.47, p < 0.01). At 12 months, spine-BMD Z-scores remained elevated in younger recipients, but did not differ in older recipients (≥ 13) and reference participants. Baseline WB-BMC Z-scores were significantly lower than reference participants (p = 0.02). Greater glucocorticoid doses were associated with declines in WB-BMC Z-scores (p < 0.001) while greater linear growth was associated with gains in WB-BMC Z-scores (p = 0.01). Changes in WB-BMC Z-scores were associated with changes in tibia cortical area Z-scores (r = 0.52, p < 0.001), but not changes in cortical BMD Z-scores. Despite resolution of muscle deficits, WB-BMC Z-scores at 12 months remained significantly reduced. These data suggest that spine and WB DXA provides insight into trabecular and cortical outcomes following pediatric renal transplantation.

Vitamin D deficiency and insufficiency after pediatric liver transplantation

Vitamin D deficiency and insufficiency are increasingly recognized in the general population, including healthy children. There is also an increasing emphasis on the importance of vitamin D status following pediatric liver transplantation and specifically its relationship to metabolic bone disease and growth retardation. Vitamin D insufficiency has also been associated with multiple immunological and metabolic disorders in adults. To our knowledge, this has not been systematically evaluated in children undergoing liver transplantation to date. Between October 2004 and August 2008, serum 25-(OH)-vitamin D levels were measured in 199 children who had undergone liver transplantation at Birmingham Children's Hospital. Potential factors contributing to vitamin D levels were evaluated. Additionally, we evaluated a possible relationship between vitamin D levels and immunological phenomena and metabolic complications. Median 25-(OH)-vitamin D level was 19.5 ng/mL (range: 4.4-71.4 ng/mL). A total of 105 children (53%) had insufficient vitamin D levels and 28 children (14%) showed vitamin D deficiency. The only factors found to be associated with vitamin D deficiency were season of sample, ethnicity, and PTH levels. Vitamin D deficiency was more prevalent during the first year after transplantation. We did not find a significant relationship between vitamin D levels and graft function or any other immunological and metabolic complications. Vitamin D insufficiency and deficiency are common in children after liver transplantation, especially in winter and spring and in non-white patients. Initial post-transplant period and high PTH are significantly associated with vitamin D deficiency. Vitamin D status should be monitored following pediatric liver transplantation and vitamin D supplementation provided as required.

Diagnosis of Osteoporosis in Children and Adolescents

Osteoporosis is traditionally regarded as a disease of elderly women. However, this bone disorder occurs in patients of both sexes and of all ages and is also increasingly recognised in the paediatric setting. In particular, patients, including young children, with other chronic diseases are at risk of developing bone fragility. There are also several forms of hereditary osteoporosis, which should be identified at an early stage to ensure adequate treatment. The diagnosis of osteoporosis in children is challenging, since their bone mineral density (BMD) is affected by growth and pubertal development. In addition to low BMD, a child must also exhibit a significant proneness to fractures before the osteoporosis diagnosis can be made. Through early diagnosis and treatment for paediatric bone fragility, we can also ameliorate bone health in adulthood. In this article we review the aetiology, known risk factors and the diagnostic criteria of osteoporosis in the young.

Impaired bone health and asymptomatic vertebral compressions in fracture-prone children: a case-control study

Frequent fractures in children may be a sign of impaired bone health, but it remains unestablished when and how fracture-prone children should be assessed. This prospective study elucidated skeletal characteristics and predisposing factors in children with recurrent fractures. Findings were used to establish guidelines for screening. During a 12-month period we recorded fracture history for all children (n = 1412) treated for an acute fracture at a large university hospital. All apparently healthy children over 4 years of age, who had sustained: (1) at least one vertebral fracture; (2) two long-bone fractures before age 10 years; or (3) three long-bone fractures before age 16 years, were recruited. They underwent dual-energy X-ray absorptiometry (DXA), laboratory tests, and spinal radiography. Information regarding family history and lifestyle factors were collected. Findings were compared with healthy controls. Sixty-six fracture-prone children (44 males, mean age 10.7 years; 5% of all children with fractures) were identified. Altogether, they had sustained 183 long-bone fractures (median 3, range 0–7); 11 children had sustained vertebral fracture(s). Patients had significantly lower bone mineral density (BMD) at lumbar spine (p < 0.001), hip (p = 0.007), and whole body (p < 0.001) than the controls; only 5 children (8%) had a BMD Z-score < −2.0. Asymptomatic vertebral compressions were prevalent, especially in those under 10 years of age. Hypercalciuria (11%) and hyperphosphaturia (22%) were significantly more prevalent than in controls. Serum concentration of 25-hydroxyvitamin D (S-25OHD) was below 50 nmol/L in 55%; low levels were associated with low BMD and vertebral compressions. The fracture-prone children had lower calcium intake, less physical activity, and more often had siblings with fractures than the controls. The findings suggest that a thorough pediatric evaluation, including DXA and spinal radiography, is often indicated already after a second significant low-energy fracture in children, in order to detect potentially preventable adverse lifestyle factors and nutritional deficits and to identify those with compromised overall bone health.

Bone metabolism in cholestatic children before and after living-related liver transplantation--a long-term prospective study

Bone disorders are common in children with end-stage liver diseases, especially those associated with cholestasis. Abnormal hepatocyte function, disordered vitamin D metabolism and calcium-phosphorous homeostasis, malnutrition, and immunosuppressive treatment are potential risk factors of bone tissue pathology before and after transplantation. The aim of the study was to analyze the long-term effect of successful living-related liver transplantation (LRLTx) on skeletal status and bone metabolism in cholestatic children. Eighteen cholestatic children (1.4±0.5yr old; 12 females [F]/6 males [M]) qualified for LRLTx were analyzed; 16 (5F/11M) of them participated in long-term observation (V4). Serum levels of osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP), cross-linked telopeptide of type 1 collagen (CTx), insulin-like growth factor I (IGF-I), IGF-I binding protein 3 (IGFBP-3), parathyroid hormone (PTH), 25-hydroxyvitamin D (25(OH)D), and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) were assayed before (V0) and 6mo (V1), 12mo (V2), 18mo (V3), and 4.4yr (V4) after LRLTx. Total body bone mineral content (TBBMC) and total body bone mineral density (TBBMD) were measured by dual-energy X-ray absorptiometry (DXA) at the same pattern. Before LRLTx, the OC, P1NP, CTx, IGF-I, and IGFBP-3 levels as well as TBBMC and TBBMD were decreased compared with age-matched control group. The mean serum levels of 25(OH)D and 1,25(OH)(2)D were within reference ranges from V0 to V4. After LRLTx, the OC, P1NP, CTx, IGF-I, and IGFBP-3 as well as TBBMC and TBBMD reached the age-matched reference values. At V4, the level of P1NP decreased below and the PTH increased above the reference range that coincided with reduced Z-scores of both TBBMC (-1.11±1.24) and TBBMD (-1.00±1.19). P1NP and CTx, both measured at V3, correlated with IGF-I at V2 (R=0.86, p=0.014 and R=0.78, p=0.021, respectively) and PTH at V3 for P1NP and V1 for CTx (R=0.64, p=0.048 and R=0.54, p=0.038, respectively). The TBBMC changes between V0 and V4 correlated with IGF-I (R=0.68, p=0.015) and 1,25(OH)(2)D (R=0.54, p=0.025), both assayed at V1. The change of TBBMC Z-scores between V0 and V4 correlated with P1NP at V1 (R=0.69, p=0.002). The TBBMD changes between V0 and V4 correlated with CTx at V1 (R=0.54, p=0.027) and P1NP change between V0 and V1 (R=0.51, p=0.038). In short-term observation, successful LRLTx led to bone metabolism normalization triggered by probable anabolic action of IGF-I and PTH and manifested by TBBMC and TBBMD increases. In long-term horizon, moderately impaired DXA assessed bone status coincided with disturbances in bone metabolism. Bone metabolism markers, especially P1NP and CTx, appeared to be good predictors of changes in bone status evaluated by DXA.

Bone density and cortical structure after pediatric renal transplantation

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area. At baseline, compared with reference participants, renal transplant recipients had significantly lower mean section modulus and muscle area; trabecular BMD was significantly greater than reference participants only in transplant recipients younger than 13 years. After transplantation, trabecular BMD decreased significantly in association with greater glucocorticoid exposure. Cortical BMD increased significantly in association with greater glucocorticoid exposure and greater decreases in parathyroid hormone levels. Muscle and fat area both increased significantly, but section modulus did not improve. At 12 months, transplantation associated with significantly lower section modulus and greater fat area compared with reference participants. Muscle area and cortical BMD did not differ significantly between transplant recipients and reference participants. Trabecular BMD was no longer significantly elevated in younger recipients and was low in older recipients. Pediatric renal transplant associated with persistent deficits in section modulus, despite recovery of muscle, and low trabecular BMD in older recipients. Future studies should determine the implications of these data on fracture risk and identify strategies to improve bone density and structure.

Endocrine and bone metabolic complications in chronic liver disease and after liver transplantation in children

With improved survival of orthotopic liver transplantation (OLT) in children, prevention and treatment of pre- and posttransplant complications have become a major focus of care. End-stage liver failure can cause endocrine complications such as growth failure and hepatic osteodystrophy, and, like other chronic illnesses, also pubertal delay, relative adrenal insufficiency, and the sick euthyroid syndrome. Drug-induced diabetes mellitus post-OLT affects approximately 10% of children. Growth failure is found in 60% of children assessed for OLT. Despite optimisation of nutrition, rarely can further stunting of growth before OLT be prevented. Catch-up growth is usually observed after steroid weaning from 18 months post-OLT. Whether growth hormone treatment would benefit the 20% of children who fail to catch up in height requires testing in randomised controlled trials. Hepatic osteodystrophy in children comprises vitamin D deficiency rickets, low bone mass, and fractures caused by malnutrition and malabsorption. Vitamin D deficiency requires aggressive treatment with ergocalciferol (D2) or cholecalciferol (D3). The active vitamin D metabolites alphacalcidol or calcitriol increase gut calcium absorption but do not replace vitamin D stores. Prevalence of fractures is increased both before OLT (10%-28% of children) and after OLT (12%-38%). Most fractures are vertebral, are associated with low spine bone mineral density, and frequently occur asymptomatically, but they may also cause chronic pain. Fracture prediction in these children is limited. OLT in children is also associated with a greater risk of developing avascular bone necrosis (4%) and scoliosis (13%-38%). This article reviews the literature on endocrine and skeletal complications of liver disease and presents preventive screening recommendations and therapeutic strategies.

Early steroid withdrawal in pediatric renal transplant: five years of follow-up

This prospective, comparative trial investigated the impact on mean change in height standard deviation score (SDS), acute rejection rate, and renal function of early steroid withdrawal in 96 recipients with 5 years of follow-up. Recipients under basiliximab induction and steroid withdrawal (SW: TAC/MMF; n = 55) were compared with a matched steroid control group (SC: TAC/MMF/STEROID, n = 41). SW received steroids until Day 6, SC decreased to 10 mg/m(2) within 2 months post-transplant. Five years after SW, the longitudinal growth (SDS) gain was 1.4 ± 0.4 vs. 1.1 ± 0.3 for SC group (p < 0.02). Height benefits in prepubertal and pubertal status in both groups were demonstrated in the delta growth trends (mixed model; p < 0.01). Biopsy-proven acute rejection in SW was 11% and 17.5%, SC (p: ns). Mean eGFR (ml/min/1.73 m(2)) at 5 years post-transplant was SW 80.6 ± 27.8 vs. 82.6 ± 25.1 for SC (p: ns). The death-censored graft survival rate at 1 and 5 years was 99 and 90% for SW; 98 and 96% for SC (p = ns). PTLD incidence in SW 3.3 vs. 2.5% in SC (p: ns). Five years post-transplant, early steroid withdrawal showed positive impacts on growth, stable renal function without increased acute rejection risk, and PTLD incidence.