Osteoporosis in children and adolescents: how to treat and monitor?

Osteoporosis is a condition of increased bone fragility associated with fractures. Apart from primary genetic osteoporotic conditions, secondary osteoporosis in children is being increasingly recognized. As a result, there is growing interest in its prevention and treatment. Important goals of care are to prevent fractures, increase bone mass and trabecular and cortical thickness, reshape vertebral fractures, prevent (or correct) skeletal deformities, and improve mobility, independence, and quality of life. Secondary pediatric osteoporosis is often of multifactorial origin since affected children frequently have more than one acquired factor that is detrimental to bone health. Typical conditions causing osteoporosis are leukemias, progressive muscle or neurological disorders, as well as chronic inflammatory conditions and their treatment. Management of children with osteoporosis involves a multidisciplinary team involving pediatric experts from different subspecialties. With regard to prevention and early intervention, it is important to provide optimal management of any underlying systemic conditions including avoidance, or dose-reduction, of osteotoxic medications. Basic supporting life-style measures, such as appropriate nutrition, including adequate calcium intake and vitamin D, and physical activity are recommended, where possible. When pediatric treatment criteria for osteoporosis are met, antiresorptive drugs constitute the first pharmacological line treatment. CONCLUSION: This clinical review focuses on the prevention, treatment, and follow-up of children with, or at risk of developing, osteoporosis and the transition from pediatric to adult care. WHAT IS KNOWN: • Osteoporosis and associated fractures can cause significant morbidity and reduce the quality of life. • The developing skeleton has huge potential for recovery and reshaping, thus early detection of fractures, assessment of recovery potential, and treatment of children with osteoporosis can prevent future fractures, deformities, and scoliosis, improve function and mobility, and reduce pain. WHAT IS NEW: • Osteoporosis in children and adolescents requires a multidisciplinary approach with a thorough assessment of recovery potential, and indication for therapy should be personalized. • Although bisphosphonates still represent the drug most commonly used to increase bone mass, improve mobility, and reduce pain and recurrence of fractures, new agents are being developed and could be beneficial in children with specific conditions.

Osteoporosis in children and adolescents: when to suspect and how to diagnose it.

Early recognition of osteoporosis in children and adolescents is important in order to establish an appropriate diagnosis of the underlying condition and to initiate treatment if necessary. In this review, we present the diagnostic work-up, and its pitfalls, of pediatric patients suspected of osteoporosis including a careful collection of the medical and personal history, a complete physical examination, biochemical data, molecular genetics, and imaging techniques. The most recent and relevant literature has been reviewed to offer a broad overview on the topic. Genetic and acquired pediatric bone disorders are relatively common and cause substantial morbidity. In recent years, there has been significant progress in the understanding of the genetic and molecular mechanistic basis of bone fragility and in the identification of acquired causes of osteoporosis in children. Specifically, drugs that can negatively impact bone health (e.g. steroids) and immobilization related to acute and chronic diseases (e.g. Duchenne muscular dystrophy) represent major risk factors for the development of secondary osteoporosis and therefore an indication to screen for bone mineral density and vertebral fractures. Long-term studies in children chronically treated with steroids have resulted in the development of systematic approaches to diagnose and manage pediatric osteoporosis. CONCLUSIONS: Osteoporosis in children requires consultation with and/or referral to a pediatric bone specialist. This is particularly relevant since children possess the unique ability for spontaneous and medication-assisted recovery, including reshaping of vertebral fractures. As such, pediatricians have an opportunity to improve bone mass accrual and musculoskeletal health in osteoporotic children. WHAT IS KNOWN: • Both genetic and acquired pediatric disorders can compromise bone health and predispose to fractures early in life. • The identification of children at risk of osteoporosis is essential to make a timely diagnosis and start the treatment, if necessary. WHAT IS NEW: • Pediatricians have an opportunity to improve bone mass accrual and musculoskeletal health in osteoporotic children and children at risk of osteoporosis. • We offer an extensive but concise overview about the risk factors for osteoporosis and the diagnostic work-up (and its pitfalls) of pediatric patients suspected of osteoporosis.

Burosumab Therapy in Children with X-Linked Hypophosphatemia.

BACKGROUND: X-linked hypophosphatemia is characterized by increased secretion of fibroblast growth factor 23 (FGF-23), which leads to hypophosphatemia and consequently rickets, osteomalacia, and skeletal deformities. We investigated burosumab, a monoclonal antibody that targets FGF-23, in patients with X-linked hypophosphatemia. METHODS: In an open-label, phase 2 trial, we randomly assigned 52 children with X-linked hypophosphatemia, in a 1:1 ratio, to receive subcutaneous burosumab either every 2 weeks or every 4 weeks; the dose was adjusted to achieve a serum phosphorus level at the low end of the normal range. The primary end point was the change from baseline to weeks 40 and 64 in the Thacher rickets severity total score (ranging from 0 to 10, with higher scores indicating greater disease severity). In addition, the Radiographic Global Impression of Change was used to evaluate rachitic changes from baseline to week 40 and to week 64. Additional end points were changes in pharmacodynamic markers, linear growth, physical ability, and patient-reported outcomes and the incidence of adverse events. RESULTS: The mean Thacher rickets severity total score decreased from 1.9 at baseline to 0.8 at week 40 with every-2-week dosing and from 1.7 at baseline to 1.1 at week 40 with every-4-week dosing (P<0.001 for both comparisons); these improvements persisted at week 64. The mean serum phosphorus level increased after the first dose in both groups, and more than half the patients in both groups had levels within the normal range (3.2 to 6.1 mg per deciliter [1.0 to 2.0 mmol per liter]) by week 6. Stable serum phosphorus levels were maintained through week 64 with every-2-week dosing. Renal tubular phosphate reabsorption increased from baseline in both groups, with an overall mean increase of 0.98 mg per deciliter (0.32 mmol per liter). The mean dose of burosumab at week 40 was 0.98 mg per kilogram of body weight with every-2-week dosing and 1.50 mg per kilogram with every-4-week dosing. Across both groups, the mean serum alkaline phosphatase level decreased from 459 U per liter at baseline to 369 U per liter at week 64. The mean standing-height z score increased in both groups, with greater improvement seen at all time points with every-2-week dosing (an increase from baseline of 0.19 at week 64) than with every-4-week dosing (an increase from baseline of 0.12 at week 64). Physical ability improved and pain decreased. Nearly all the adverse events were mild or moderate in severity. CONCLUSIONS: In children with X-linked hypophosphatemia, treatment with burosumab improved renal tubular phosphate reabsorption, serum phosphorus levels, linear growth, and physical function and reduced pain and the severity of rickets. (Funded by Ultragenyx Pharmaceutical and Kyowa Hakko Kirin; ClinicalTrials.gov number, NCT02163577 ; EudraCT number, 2014-000406-35 ).

The Many Facets of Vitamin D in the Pediatric Population.

Vitamin D is important for skeletal growth, bone mineralization and dental health. Vitamin D deficiency is reported in many countries, may have several causes and can cause rickets in children. A guideline with recommendations of vitamin D supplementation to prevent nutritional rickets was published recently. The vitamin D receptor is present in many cells of the body including cells of the immune system. Many studies have been published on associations between vitamin D deficiency and extra skeletal effects, mainly without proof of causality in intervention studies. This review aims to summarize available evidence of the skeletal and extra-skeletal effects of vitamin D. For the extra-skeletal effects there is proof that vitamin D supplementation can prevent acute respiratory infections in children with vitamin D deficiency and can reduce the rate of asthma exacerbations requiring corticosteroids in children with vitamin D deficiency. The evidence of benefit of vitamin D supplementation is too limited for pediatric patients with other infectious, inflammatory, and autoimmune diseases.

Automated radiogrammetry is a feasible method for measuring bone quality and bone maturation in severely disabled children.

BACKGROUND: Children with severe neurological impairment and intellectual disability are prone to low bone quality and fractures. OBJECTIVE: We studied the feasibility of automated radiogrammetry in assessing bone quality in this specific group of children. We measured outcome of bone quality and, because these children tend to have altered skeletal maturation, we also studied bone age. MATERIALS AND METHODS: We used hand radiographs obtained in 95 children (mean age 11.4 years) presenting at outpatient paediatric clinics. We used BoneXpert software to determine bone quality, expressed as paediatric bone index and bone age. RESULTS: Regarding feasibility, we successfully obtained a paediatric bone index in 60 children (63.2%). The results on bone quality showed a mean paediatric bone index standard deviation score of -1.85, significantly lower than that of healthy peers (P < 0.0001). Almost 50% of the children had severely diminished bone quality. In 64% of the children bone age diverged more than 1 year from chronological age. This mostly concerned delayed bone maturation. CONCLUSION: Automated radiogrammetry is feasible for evaluating bone quality in children who have disabilities but not severe contractures. Bone quality in these children is severely diminished. Because bone maturation frequently deviated from chronological age, we recommend comparison to bone-age-related reference values.

Vitamin D in childhood and adolescence: an expert position statement.

UNLABELLED: Vitamin D is a key hormone in the regulation of calcium and phosphorus metabolism and plays a pivotal role in bone health, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur. Great interest has been placed in recent years on vitamin D's extraskeletal actions. However, while recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious and autoimmune diseases, the actual impact of vitamin D status on the global health of children and adolescents, other than bone, remains a subject of debate. In the meantime, pediatricians still need to evaluate the determinants of vitamin D status and consider vitamin D supplementation in children and adolescents at risk of deficiency. This review is the result of an expert meeting that was held during the congress "Update on vitamin D and bone disease in childhood" convened in Pisa, Italy, in May 2013. CONCLUSION: The collaboration of the international group of experts produced this "state of the art" review on vitamin D in childhood and adolescence. After dealing with vitamin D status and its determinants, the review outlines the current debate on vitamin D's health benefits, concluding with a practical approach to vitamin D supplementation during childhood and adolescence. WHAT IS KNOWN: • Vitamin D deficiency is a worldwide health problem. • Vitamin D deficiency affects not only musculoskeletal health but also a potentially wide range of acute and chronic diseases. What is New: • We reviewed the literature focusing on randomized controlled trials of vitamin D supplementation during childhood and adolescence. • This review will help pediatricians to appreciate the clinical relevance of an adequate vitamin D status and it will provide a practical approach to vitamin D supplementation.

Common DNA variants predict tall stature in Europeans.

Genomic prediction of the extreme forms of adult body height or stature is of practical relevance in several areas such as pediatric endocrinology and forensic investigations. Here, we examine 770 extremely tall cases and 9,591 normal height controls in a population-based Dutch European sample to evaluate the capability of known height-associated DNA variants in predicting tall stature. Among the 180 normal height-associated single nucleotide polymorphisms (SNPs) previously reported by the Genetic Investigation of ANthropocentric Traits (GIANT) genome-wide association study on normal stature, in our data 166 (92.2 %) showed directionally consistent effects and 75 (41.7 %) showed nominally significant association with tall stature, indicating that the 180 GIANT SNPs are informative for tall stature in our Dutch sample. A prediction analysis based on the weighted allele sums method demonstrated a substantially improved potential for predicting tall stature (AUC = 0.75; 95 % CI 0.72-0.79) compared to a previous attempt using 54 height-associated SNPs (AUC = 0.65). The achieved accuracy is approaching practical relevance such as in pediatrics and forensics. Furthermore, a reanalysis of all SNPs at the 180 GIANT loci in our data identified novel secondary association signals for extreme tall stature at TGFB2 (P = 1.8 × 10(-13)) and PCSK5 (P = 7.8 × 10(-11)) suggesting the existence of allelic heterogeneity and underlining the importance of fine analysis of already discovered loci. Extrapolating from our results suggests that the genomic prediction of at least the extreme forms of common complex traits in humans including common diseases are likely to be informative if large numbers of trait-associated common DNA variants are available.

Fibroblast growth factor 23 and calcium-phosphate metabolism in relation to cardiovascular risk factors in patients with type 1 diabetes.

BACKGROUND: Cardiovascular disease (CVD) is the major cause of mortality in type 1 diabetes (T1D). The objective of this study is to evaluate fibroblast growth factor 23 (FGF23) and calcium-phosphate metabolism in relation to cardiovascular risk factors in adults with and without T1D. METHODS: A case-control study was conducted using data from patients with T1D and age- and sex matched controls without T1D from the Lifelines Cohort Study. RESULTS: We included 302 adults in the T1D group and 302 adults in the control group. Median age was 42 years. Median glycosylated hemoglobin (HbA1c) in the T1D group was 7.8%. FGF23 of all patients with T1D was not significantly different from controls. Females with T1D had significantly higher FGF23 than males with T1D (83.3 vs 69.3 U/mL, p = 0.002), this was not observed in controls. Serum phosphate, calcium, and alkaline phosphatase were higher and parathyroid hormone was lower in patients with T1D, compared to controls (all p < .001), all within normal range. In the T1D group, FGF23 was positively correlated with serum phosphate (p < .001), alkaline phosphatase (p = .01), and calcium (p = .030), these correlations were not observed in controls. Median FGF23 was significantly higher in current smokers than in nonsmokers with T1D (84.9 vs 73.5 U/mL, p < .05). CONCLUSIONS: Serum calcium, phosphate, and alkaline phosphatase were higher in patients with T1D than in controls and were positively correlated to FGF23 in patients with T1D. Current smokers with T1D had higher FGF23 than nonsmokers with T1D. These findings may contribute to the increased risk of CVD in patients with T1D.

A patient-centred and multi-stakeholder co-designed observational prospective study protocol: Example of the adolescent experience of treatment for X-linked hypophosphataemia (XLH).

The importance of patient centricity and keeping the patient at the heart of research design is now well recognised within the healthcare community. The involvement of patient, caregiver and clinician representatives in the study design process may help researchers to achieve this goal and to ensure robust and meaningful data generation. Real-world data collection allows for a more flexible and patient-centred research approach for gaining important insights into the experience of disease and treatments, which is acutely relevant for rare diseases where knowledge about the disease is more likely to be limited. Here, we describe a practical example of a patient-centric, multi-stakeholder approach that led to the co-design of a prospective observational study investigating the lived experience of adolescents with the rare disease, X-linked hypophosphataemia. Specifically, we describe how the knowledge and expertise of a diverse research team, which included expert physicians, research and technology specialists, patients and caregivers, were applied in order to identify the relevant research questions and to ensure the robustness of the study design and its appropriateness to the population of interest within the context of the current clinical landscape. We also demonstrate how a structured patient engagement exercise was key to informing the selection of appropriate outcome measures, data sources, timing of data collection, and to assessing the feasibility and acceptability of the proposed data collection approach.

The effect of the Taq1A variant in the dopamine D2 receptor gene and common CYP2D6 alleles on prolactin levels in risperidone-treated boys.

OBJECTIVE: To investigate the effect of the Taq1A variant in the Dopamine D2 receptor gene (DRD2) and common functional genetic variants in the cytochrome P450 2D6 gene (CYP2D6) on prolactin levels in risperidone-treated boys with autism spectrum disorders and disruptive behavior disorders. METHODS: Forty-seven physically healthy 10-year-old to 19-year-old boys with autism spectrum disorders and/or disruptive behavior disorders, chronically treated (mean 52 months, range 16-126 months) with an antipsychotic, were recruited into this observational study. Prolactin levels, hyperprolactinemia, risperidone levels, and 9-hydroxyrisperidone levels were assessed and the participants were genotyped for common CYP2D6 polymorphisms and the Taq1A allele of the dopamine D2 receptor gene. Group differences were tested using Student's t-test, χ², and logistic regression analysis. RESULTS: Prolactin levels were associated positively and significantly with risperidone levels (P=0.05), 9-hydroxyrisperidone levels (P≤0.0001), and with the oral risperidone dose in milligrams per kilogram (P≤0.0001). Furthermore, multiple regression analysis showed no correlations between prolactin level and the presence of at least one Taq1A A1 allele of the DRD2 gene (P=0.12). CONCLUSION: Although CYP2D6 might have an effect, the presence of at least one Taq1A A1 allele of the D2DR gene did not contribute toward susceptibility to risperidone-induced hyperprolactinemia, and as a result, toward prolactin-related adverse events such as amenorrhea, galactorrhea, and sexual dysfunctioning.

A novel mutation in PTHLH in a family with a variable phenotype with brachydactyly, short stature, oligodontia and developmental delay.

Mutations in PTHLH (PTH-like hormone), cause brachydactyly type E (BDE) characterized by shortening of metacarpals, metatarsals and/or phalanges with short stature. In this report we describe three siblings and their mother with a novel heterozygous mutation c.25 T > C, p.Trp9Arg in exon 2 of the PTHLH gene. Beside the known clinical features of PTHLH mutations all had a delay in speech and language development, unknown if this is related to the mutation. Patients with PTHLH mutation may have a variable phenotypic presentation.

Ten-Year Experience of a Global and Freely Accessible e-Learning Website for Pediatric Endocrinology and Diabetes.

The European Society for Paediatric Endocrinology (ESPE) interactive website, https://www.espe-elearning.org, was first published online in 2012. We describe the various applications of the content of the e-learning website that has been greatly expanded over the last 10 years. A large module on pediatric diabetes was added with the support of the International Society for Paediatric and Adolescent Diabetes (ISPAD). A separate multilingual module was created that focuses on frontline health care providers in limited resource settings. This module has been well received, particularly in targeted parts of the world. e-Learning may also be an opportunity to expand or tailor educational activities for learners according to their differing learning needs. The e-learning website provides guidelines for those interested in general pediatrics, neonatology, clinical genetics, and pediatric gynecology. We also describe various new applications such as master classes in the format of interactive video lectures and joint and complementary e-learning/e-consultation webinars. Finally, international certification was recently realized as e-learning courses were recognized by the European Accreditation Council for Continuing Medical Education (EACCME). As a result of the social distancing measures introduced to control the COVID-19 pandemic, digital education, whether individual or in a virtual classroom setting, has become even more important since e-learning can connect and engage individuals across geographic boundaries as well as those who live in remote areas. The future of education delivery may include hybrid learning strategies, which include in-person and e-learning platforms. Combined e-learning and e-consultation webinars illustrate how international academic institutions, learned medical specialty societies and networks are uniquely placed to deliver balanced, disease-oriented, and patient-centered e-learning education and at the same time provide expert consultation. Moreover, they are well equipped to maintain professional standards and to offer appropriate accreditation.

The International X-Linked Hypophosphatemia (XLH) Registry: first interim analysis of baseline demographic, genetic and clinical data.

BACKGROUND: X-linked hypophosphatemia (XLH) is a rare, hereditary, progressive, renal phosphate-wasting disorder characterized by a pathological increase in FGF23 concentration and activity. Due to its rarity, diagnosis may be delayed, which can adversely affect outcomes. As a chronic disease resulting in progressive accumulation of musculoskeletal manifestations, it is important to understand the natural history of XLH over the patient's lifetime and the impact of drug treatments and other interventions. This multicentre, international patient registry (International XLH Registry) was established to address the paucity of these data. Here we present the findings of the first interim analysis of the registry. RESULTS: The International XLH Registry was initiated in August 2017 and includes participants of all ages diagnosed with XLH, regardless of their treatment and management. At the database lock for this first interim analysis (29 March 2021), 579 participants had entered the registry before 30 November 2020 and are included in the analysis (360 children [62.2%], 217 adults [37.5%] and 2 whose ages were not recorded [0.3%]; 64.2% were female). Family history data were available for 319/345 (92.5%) children and 145/187 (77.5%) adults; 62.1% had biological parents affected by XLH. Genetic testing data were available for 341 (94.7%) children and 203 (93.5%) adults; 370/546 (67.8%) had genetic test results; 331/370 (89.5%) had a confirmed PHEX mutation. A notably longer time to diagnosis was observed in adults ≥ 50 years of age (mean [median] duration 9.4 [2.0] years) versus all adults (3.7 [0.1] years) and children (1.0 [0.2] years). Participants presented with normal weight, shorter length or height and elevated body mass index (approximately - 2 and + 2 Z-scores, respectively) versus the general population. Clinical histories were collected for 349 participants (239 children and 110 adults). General data trends for prevalence of bone, dental, renal and joint conditions in all participants were aligned with expectations for a typical population of people with XLH. CONCLUSION: The data collected within the International XLH Registry, the largest XLH registry to date, provide substantial information to address the paucity of natural history data, starting with demographic, family history, genetic testing, diagnosis, auxology and baseline data on clinical presentation.

Clinical presentation and molecular genetic analysis of a Sudanese family with a novel mutation in the CYP2R1 gene.

The aim of this study was to identify the genetic basis of two female siblings - born to consanguineous Sudanese parents - diagnosed clinically as having the rare condition of 25-hydroxylase deficiency (vitamin D-dependent rickets type 1B). The initial diagnosis was established based on clinical data, laboratory and radiological findings retrospectively. Primers for all exons (5) of human CYP2R1 (NM_024514) were generated followed by Sanger sequencing on exons 1-5 for both girls and their parents. Homozygosity for a point mutation (c.85C > T) was detected, leading to a nonsynonymous variant at position 29 in exon 1, resulting in a premature stop codon (p.Q29X). This is a previously unknown variant that leads to a severely truncated protein and predicted to be among the 0.1 % most deleterious genomic variants(CADD score 36). To our knowledge, this family represents the first case series from Sudan with a confirmed CYP2R1 gene mutation and the 6th world-wide. With the lack of genetic facilities, diagnosis should be suspected by the persistently low 25 hydroxyvitamin D level in spite of proper treatment and after ruling out liver disease and malabsorption. Patients in this case series showed healing of rickets when treated with high doses of 1,25-dihydroxyvitamin D3 (1,25(OH)D3; calcitriol) and oral calcium.

Changes in body size and body composition in survivors of childhood cancer: seven years follow-up of a prospective cohort study.

BACKGROUND & AIMS: Cancer treatment is known to have impact on nutritional status, and both underweight and overweight have been reported in several studies in survivors. A limitation of most studies is that they relied on retrospective data or were limited to a subgroup of patients. The current study aims to describe changes in body size and body composition prospectively seven years after diagnosis in a heterogeneous sample of childhood cancer survivors and to evaluate associated factors. METHODS: The study population consisted of children diagnosed with hematological, solid and brain malignancies aged 0-18 years at diagnosis. Data of body size, body composition, and associated factors were collected at diagnosis, one year and seven years after diagnosis. RESULTS: In the total cohort mean BMI z-score increased during treatment. In children with hematological and brain malignancies BMI z-score continued to increase after end of treatment leading to quadrupling of the prevalence of obesity seven years after diagnosis. BMI at diagnosis (ß = -0.34, P = 0.007) and maternal BMI (ß = 0.25, P = 0.046) were associated with the increase in BMI z-score. Mean fat mass (FM) z-score, already high at diagnosis, increased during treatment in children with hematological and brain malignancies and evened out during follow-up. Changes in FM z-score were predicted by type of malignancy (hematologic malignancy versus solid tumor ß = 0.48, P = 0.008; brain tumor versus solid tumor ß = 0.45, P = 0.012). Mean fat free mass (FFM) z-scores started low at diagnosis, particularly in patients with brain tumors, increased during treatment in patients with solid and brain malignancies, though decreased in children with hematological malignancies. At 7 years follow-up a clear increase to normal was seen. Age at diagnosis (ß = 0.43, P = 0.004) and initial FFM (ß = -0.49, P = 0.001) were found to be significant predictors for changes in FFM z-scores. CONCLUSIONS: The finding that the once obtained extra weight and FM during treatment persisted after termination of treatment in children with hematological and brain malignancies, stresses the importance to create awareness about the risk of developing overweight in children during cancer treatment.

Sustained Efficacy and Safety of Burosumab, a Monoclonal Antibody to FGF23, in Children With X-Linked Hypophosphatemia.

PURPOSE: In X-linked hypophosphatemia (XLH), excess fibroblast growth factor-23 causes hypophosphatemia and low calcitriol, leading to musculoskeletal disease with clinical consequences. XLH treatment options include conventional oral phosphate with active vitamin D, or monotherapy with burosumab, a monoclonal antibody approved to treat children and adults with XLH. We have previously reported outcomes up to 64 weeks, and here we report safety and efficacy follow-up results up to 160 weeks from an open-label, multicenter, randomized, dose-finding trial of burosumab for 5- to 12-year-old children with XLH. METHODS: After 1 week of conventional therapy washout, patients were randomized 1:1 to burosumab every 2 weeks (Q2W) or every 4 weeks (Q4W) for 64 weeks, with dosing titrated based on fasting serum phosphorus levels between baseline and week 16. From week 66 to week 160, all patients received Q2W burosumab. RESULTS: Twenty-six children were randomized initially into each Q2W and Q4W group and all completed treatment to week 160. In 41 children with open distal femoral and proximal tibial growth plates (from both treatment groups), total Rickets Severity Score significantly decreased by 0.9 ±â€…0.1 (least squares mean ±â€…SE; P < 0.0001) from baseline to week 160. Fasting serum phosphorus increases were sustained by burosumab therapy throughout the study, with an overall population mean (SD) of 3.35 (0.39) mg/dL, within the pediatric normal range (3.2-6.1 mg/dL) at week 160 (mean change from baseline P < 0.0001). Most adverse events were mild to moderate in severity. MAIN CONCLUSIONS: In children with XLH, burosumab administration for 160 weeks improved phosphate homeostasis and rickets and was well-tolerated. Long-term safety was consistent with the reported safety profile of burosumab. CLINICALTRIALS.GOV: NCT02163577.

Post-authorisation safety study of burosumab use in paediatric, adolescent and adult patients with X-linked hypophosphataemia: rationale and description.

Background: X-linked hypophosphataemia (XLH) is a rare, inherited, phosphate-wasting disorder that elevates fibroblast growth factor 23 (FGF23), causing renal phosphate-wasting and impaired active vitamin D (1,25(OH)2D) synthesis. Disease characteristics include rickets, osteomalacia, odontomalacia, and short stature. Historically, treatment has been oral phosphate and 1,25(OH)2D supplements. However, these treatments do not correct the primary pathogenic mechanism or treat all symptoms and can be associated with adverse effects. Burosumab is a recombinant human immunoglobulin G1 monoclonal antibody against FGF23, approved for treating XLH in several geographical regions, including Europe and Israel. Burosumab restores normal serum phosphate levels, minimising the clinical consequences of XLH. Safety data on long-term treatment with burosumab are lacking owing to the rarity of XLH. This post-authorisation safety study (PASS) aims to evaluate the safety outcomes in patients aged >1 year. Methods: The PASS is a 10-year retrospective and prospective cohort study utilising data from the International XLH Registry (NCT03193476), which includes standard diagnostic and monitoring practice data at participating centres. The PASS aims to evaluate frequency and severity of safety outcomes, frequency and outcomes of pregnancies in female patients, and safety outcomes in patients with mild to moderate kidney disease at baseline, in children, adolescents and adults treated with burosumab for XLH. It is expected that there will be at least 400 patients who will be administered burosumab. Results: Data collection started on 24 April 2019. The expected date of the final study report is 31 December 2028, with two interim reports. Conclusion: This PASS will provide data on the long-term safety of burosumab treatment for XLH patients and describe safety outcomes for patients receiving burosumab contrasted with those patients receiving other XLH treatments, to help inform the future management of XLH patients. The PASS will be the largest real-world safety study of burosumab. Registry identification: The International XLH Registry is registered with clinicaltrials.gov as NCT03193476 (https://clinicaltrials.gov/ct2/show/NCT03193476), and the PASS is registered with the European Union electronic Register of Post-Authorisation Studies as EUPAS32190 (http://www.encepp.eu/encepp/viewResource.htm?id=32191).

The relation between 25-hydroxyvitamin D with peak bone mineral density and body composition in healthy young adults.

OBJECTIVE: The associations between peak bone mineral density (BMD) and body composition with 25 hydroxyvitamin D (25OHD) levels in healthy young adults were evaluated. METHODS: The number of participants was 464; 347 women and 117 men. The mean age was 24.3 years (range 17-31 years). BMD of the lumbar spine, total body and femoral neck (FN) and body composition were measured by dual energy X-ray absorptiometry. Volumetric BMD, bone mineral apparent density (BMAD), of the lumbar spine and FN was calculated. RESULTS: In females, 25OHD level was positively associated with FN BMD and BMAD (both p<0.01) and negatively with percentage body fat (p<0.001). In males, 25OHD levels had a positive association with total body BMD and lean body mass (p=0.03 and p=0.01). CONCLUSIONS: 25OHD level is a determinant of peak BMD in both sexes. Vitamin D status was associated with body fat in females and with lean body mass in males.

Chondrodysplasia, enchondromas and a chest deformity causing severe pulmonary morbidity in a boy with a PTHLH duplication: A case report.

Parathyroid hormone-like hormone (PTHLH) plays an important role in bone formation. Several skeletal dysplasias have been described that are associated with disruption of PTHLH functioning. Here we report on a new patient with a 898 Kb duplication on chromosome 12p11.22 including the PTHLH gene. The boy has multiple skeletal abnormalities including chondrodysplasia, lesions radiographically resembling enchondromas and posterior rib deformities leading to a severe chest deformity. Severe pulmonary symptoms were thought to be caused by limited mobility and secondary sputum evacuation problems due to the chest deformity. Imaging studies during follow-up revealed progression of the number of skeletal lesions over time. This case extends the phenotypic spectrum associated with copy number variation of PTHLH.

Bone Mineral Density in Adult Survivors of Pediatric Differentiated Thyroid Carcinoma: A Longitudinal Follow-Up Study.

Background: Survivors of pediatric differentiated thyroid carcinoma (DTC) receive thyrotropin-suppressive therapy to minimize disease recurrence. However, knowledge about long-term effects of subclinical hyperthyroidism on bone mineral density (BMD) in pediatric DTC survivors is scarce, as is the information regarding long-term consequences of permanent hypoparathyroidism on BMD. We evaluated BMD in pediatric DTC survivors and investigated if BMD was affected by subclinical hyperthyroidism and/or permanent hypoparathyroidism during long-term follow-up. Methods: In this nationwide longitudinal study, we determined BMD in the lumbar spine and femur by dual energy X-ray absorptiometry in 65 pediatric DTC survivors. Measurements were repeated after minimal 5 years of follow-up in 46 pediatric DTC survivors. BMD results were evaluated according to the recommendations of the International Society for Clinical Densitometry (ISCD) and WHO. At both visits, we determined biochemical parameters and markers of bone resorption (C-terminal telopeptide of type I collagen [ß-CTX]) and formation (N-propeptide of type I collagen [PINP] and osteocalcin). Results: First and second BMD measurements were done after a median follow-up of 17.0 (interquartile range [IQR] 8.0-25.0) and 23.5 (IQR 14.0-30.0) years after diagnosis, respectively. Median age at diagnosis was 15 years (IQR 13.0-17.0). Twenty-nine percent of the survivors had subclinical hyperthyroidism. In most survivors, BMD T- and Z-scores were within the reference range during both BMD evaluations. However, after 23.5 years of follow-up, a low BMD was found in 13.0%. In the 13 survivors with permanent hypoparathyroidism, BMD values did not differ after 5 years of follow-up compared with baseline values or in comparison with the 33 survivors without permanent hypoparathyroidism. During follow-up, turnover markers ß-CTX and PINP remained stable. Conclusions: This longitudinal study of pediatric DTC survivors demonstrated normal and stable median lumbar spine and femur BMD values after a median time of 17 and 23.5 years after diagnosis. However, compared with controls, a lower BMD was still found in 13.0% after prolonged follow-up despite intensive follow-up. Based on the studied follow-up period, these data do not provide convincing evidence in support of standard monitoring of bone mass among DTC survivors, but may be restricted to individual cases at low frequency. Trial Registration: This follow-up study was registered in The Netherlands Trial Register under no. NL3280 (www.trialregister.nl/trial/3280).