Vitamin D testing in children and adolescents in Victoria, Australia: are testing practices in line with global recommendations?

OBJECTIVE

To describe changing primary care ordering of serum 25-hydroxyvitamin D (25OHD) tests in Australian children.

DESIGN

Longitudinal, population-based descriptive study of 25OHD testing using a large administrative dataset of pathology orders and results, 2003-2018.

SETTING AND PARTICIPANTS

Three primary health networks in Victoria, Australia. Patients aged ≤18 years with a serum 25OHD test ordered by the general practitioner (GP).

MAIN OUTCOME MEASURES

Trends over 15 years in the number of 25OHD tests ordered, proportion indicating low levels or vitamin D deficiency and details of repeat testing.

RESULTS

Of 970 816 laboratory tests, 61 809 (6.4%) included an order for a 25OHD test. The 61 809 tests were performed in 46 960 children or adolescents. The odds of ordering a 25OHD test in 2018 was 30.4 times higher compared with 2003 (95%CI 22.6 to 40.8, p<0.001). The odds of detecting a low 25OHD (<50 nmol/L) compared with the baseline in 2003 remained steady (adjusted OR<1.5) over time. Repeat tests (14 849) were undertaken in 9626 patients (median intertest interval 357 days, IQR 172-669 days). A total of 4603 test results indicated vitamin D deficiency (<30 nmol/L), but in only 180 (3.9%) of these was a repeat test performed within 3 months as recommended.

CONCLUSION

Testing volumes increased 30-fold, but the odds of detecting low 25OHD remained steady. Current Australian policy and the Global Consensus Recommendations for the prevention and management of nutritional rickets do not support routine 25OHD testing. Education and electronic pathology ordering tools may assist GPs to better align practice with current recommendations.

SUN-083 Screening of Vitamin D and Calcium Concentrations in Neonates of Mothers at High Risk of Vitamin D Deficiency

Objective: The aim of this study was to determine, retrospectively, the serum 25OHD and calcium concentrations of screened neonates of mothers at high risk of 25OHD deficiency (maternal 25OHD < 25 nmol/L or unknown vitamin D concentrations and risk factors for vitamin D deficiency) and critically analyse whether their measurements contributes to the management of these neonates.

Methods: Serum 25OHD and calcium concentrations from 600 samples of umbilical cord blood or venous blood collected from neonates over a 12-month period were analysed. 25OHD concentrations were reported for all while both the corrected calcium concentrations and vitamin D concentrations were available for 569 samples.

Results: There was little or no evidence of association between neonatal 25OHD concentrations and gender, gestational age or birth weight. There was a high prevalence of vitamin D insufficiency (27.6%, 30–50 nmol/L) and deficiency (21.3%, < 30 nmol/L) in neonates from high-risk maternal groups. There was a statistically positive but weak correlation (ρ = 0.22, P < 0.0001) between serum calcium and 25OHD concentrations. Only 7 neonates out of 569 (1.2%) had calcium levels in the hypocalcaemic range; however, a significant number (47.6%) were reported to be in the hypercalcaemic range. Nearly all of these were venous samples collected in first 24 hours after birth. We calculated the reference interval for corrected calcium from our data of venous samples in first 24 hours and the upper limit was significantly higher (2.38–3.04 mmol/L) than the standard reference range used.

Conclusion: Vitamin D deficiency is prevalent in neonates of high-risk mothers but the risk of hypocalcaemia due to vitamin D deficiency at birth is low. Screening neonates entails blood testing which can cause distress to neonates and their parents, substantial impost on staff and financial burden on the health care system. 25OHD deficiency is corrected relatively easily in neonates with supplementation and vitamin D supplementation of neonates from birth without routine screening appears to offer better value of care. Also, the data from this study suggest that the paediatric reference range for corrected calcium concentrations in neonates is higher and the paediatric reference range should be reconsidered.

Diagnosis of Recurrent Fracture in a Pediatric Cohort

Significant fracture history in children is defined as having at least one vertebral fracture, at least 2 fractures by age 10, or at least 3 fractures by age 19. Between September 2011 and December 2014, clinical data were collected on children with a significant fracture history that attended a major Australian children's hospital. Fifty-six patients were identified as having 305 fractures in total, including 44 vertebral fractures. 18% of patients (10/56) were diagnosed with osteogenesis imperfecta (OI) by a bone health expert, molecular testing or both, and they sustained 23% of all fractures (71/305). Analysis of serum bone biochemistry showed all median values to be within a normal range and no clinically significant differences between patients with and without OI. The DXA and pQCT derived bone mineral density (BMD) and bone mineral content (BMC) Z scores were reduced overall. DXA derived total body and lumbar spine areal BMD-for-age and BMC-for-age Z scores were significantly lower in children who had vertebral fractures or who were later diagnosed with OI. Similarly, pQCT performed on radii and tibiae showed Z scores significantly less than zero. pQCT-derived limb muscle cross sectional area Z scores were significantly lower in the OI subgroup. In conclusion, this study describes the bone phenotype of children referred to a tertiary hospital clinic for recurrent fractures and highlights a subset of children with previously undiagnosed OI, but a larger cohort without classic OI. Thus it can be clinically challenging to differentiate between children with OI type 1 (mild phenotype) and non-OI children without bone densitometry and genetic testing. We conclude that recurrent fractures in children should prompt a comprehensive bone and systemic health assessment to eliminate an underlying pathology.

MANAGEMENT OF ENDOCRINE DISEASE: Therapeutics of Vitamin D

OBJECTIVE

The central role of vitamin D in bone health is well recognized. However, controversies regarding its clinical application remain. We therefore aimed to review the definition of hypovitaminosis D, the skeletal and extra-skeletal effects of vitamin D and the available therapeutic modalities.

DESIGN

Narrative and systematic literature review.

METHODS

An international working group that reviewed the current evidence linking bone and extra-skeletal health and vitamin D therapy to identify knowledge gaps for future research.

RESULTS

Findings from observational studies and randomized controlled trials (RCTs) in vitamin D deficiency are discordant, with findings of RCTs being largely negative. This may be due to reverse causality with the illness itself contributing to low vitamin D levels. The results of many RCTs have also been inconsistent. However, overall evidence from RCTs shows vitamin D reduces fractures (when administered with calcium) in the institutionalized elderly. Although controversial, vitamin D reduces acute respiratory tract infections (if not given as bolus monthly or annual doses) and may reduce falls in those with the lowest serum 25-hydroxyvitamin D (25OHD) levels. However, despite large ongoing RCTs with 21 000–26 000 participants not recruiting based on baseline 25OHD levels, they will contain a large subset of participants with vitamin D deficiency and are adequately powered to meet their primary end-points.

CONCLUSIONS

The effects of long-term vitamin D supplementation on non-skeletal outcomes, such as type 2 diabetes mellitus (T2DM), cancer and cardiovascular disease (CVD) and the optimal dose and serum 25OHD level that balances extra-skeletal benefits (T2DM) vs risks (e.g. CVD), may soon be determined by data from large RCTs.

Long-Term Bisphosphonate Therapy in Osteogenesis Imperfecta

PURPOSE OF REVIEW

Osteogenesis imperfecta (OI) is a genetic bone disorder resulting in bone fragility. It has a heterogeneous phenotype which typically includes reduced bone mass, multiple fractures, deformity, and chronic disability. Bisphosphonate treatment remains the first-line medical management, but there is still debate on aspects of its effectiveness. This review summarizes current knowledge about long-term bisphosphonate use in OI with recommendations on clinical application.

RECENT FINDINGS

Bisphosphonates increase bone mineral density, most notably of the vertebrae, and reduce fracture risk in the pediatric OI population. Gains in strength and mobility, together with the permissive effect on orthopedic surgery (e.g., in combination with intramedullary rodding) and physiotherapy, have resulted in improved quality of life for those with OI. As experience in its use continues, the risks and benefits of long-term bisphosphonate treatment in OI are slowly emerging. Patient registries containing data on genotype, phenotype, fractures, bisphosphonate treatment, orthopedic intervention, and functional outcomes are essential for systematic evaluation given the lack of large multi-centered randomized control trials.

The importance of vitamin D in maternal and child health: a global perspective

Vitamin D and calcium are important nutrients for skeletal growth and bone health. Children and pregnant women are particularly vulnerable to 25-hydroxy vitamin D deficiency (VDD). VDD, with or without dietary calcium deficiency, can lead to nutritional rickets (NR), osteomalacia, and disturbances in calcium homeostasis. Multiple studies have linked VDD to adverse health outcomes in both children and pregnant women that extend beyond bone health. VDD remains an important global public health concern, and an important differentiation must be made between the impact of VDD on children and adults. Reports of increased incidence of NR continue to emerge. NR is an entirely preventable condition, which could be eradicated in infants and children worldwide with adequate vitamin D and calcium supplementation. The desire and necessity to put in place systems for preventing this potentially devastating pediatric disease should not elicit dispute. VDD and NR are global public health issues that require a collaborative, multi-level approach for the implementation of feasible preventative strategies. This review highlights the history, risk factors, and controversies related to VDD during pregnancy and childhood with a particular focus on global NR prevention.

Protocol for a randomised control trial of bisphosphonate (zoledronic acid) treatment in childhood femoral head avascular necrosis due to Perthes disease

INTRODUCTION

Perthes disease (PD) is an idiopathic disorder presenting with avascular necrosis to the femoral head, which frequently results in flattening. Long-term function is directly related to the subsequent femoral head sphericity. Current treatment includes mechanical modalities and surgical procedures, which are therapeutic but are not uniformly able to prevent collapse. The use of the nitrogen-containing bisphosphonate zoledronic acid (ZA) to inhibit osteoclastic bone resorption is aimed at preserving femoral head strength, reducing collapse and thus maintaining shape. The proposed multicentre, prospective, randomised controlled trial intends to evaluate the efficacy of ZA treatment in PD.

METHODS AND ANALYSIS

An open-label randomised control trial recruiting 100 children (50 each treatment arm) 5 to 16 years old with unilateral PD. Subjects are randomly assigned to either (a) ZA and standard care or (b) Standard care. The primary outcome measure is deformity index (DI), a radiographic parameter of femoral head roundness assessed at 24 months, following 12 months of ZA treatment (3-monthly doses of ZA 0.025 mg/kg at baseline, 3, 6, 9 and 12 months) plus 12 months observation (group A) or 24 months of observation (group B). Secondary outcome measures are femoral head subluxation, Faces Pain scale, Harris hip score and quality of life. Assessments are made at baseline, 3 monthly during the first year of follow-up and then 6 monthly, until the 24th month.

ETHICS AND DISSEMINATION

The study commenced following the written approval from the Human Research Ethics Committee. Safety considerations regarding the effects of ZA are monitored which include the subject's symptomatology, mineral status, bone mass and turnover activity, and metaphyseal modelling. Data handling plan requires that all documents, clinical information, biological samples and investigation results will be held in strict confidence by study investigators to preserve its safety and confidentiality.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials ACTRN12610000407099, pre-results.

Osteogenesis imperfecta: diagnosis and treatment

Osteogenesis imperfecta (OI) is a genetic bone fragility disorder characterized by low bone mass, skeletal deformity, and variable short stature. OI is predominantly caused by dominant mutations affecting type 1 collagen synthesis, with a number of other genes implicated in OI over recent years. The clinical severity of OI can vary greatly, even within families who share a common mutation. Optimal management of OI requires a multidisciplinary approach involving pediatrician, endocrinologist (bone and mineral physician), rehabilitation specialist, orthopedic surgeon, dentist, geneticist, social worker/psychologist, physiotherapist, and occupational therapist. Bisphosphonate therapy remains the mainstay of medical treatment in OI and has been shown to decrease bone pain, enhance well-being, improve muscle strength and mobility and decrease fracture incidence. Novel therapies are beginning to emerge as more is understood about the signaling pathways involved in bone formation. The following summarizes the diagnosis, genetic heterogeneity and management of OI in pediatric practice.

Intravenous pamidronate treatment in children with moderate-to-severe osteogenesis imperfecta started under three years of age

OBJECTIVE

Evaluate clinical outcome of early cyclic intravenous pamidronate treatment in children with moderate-to-severe osteogenesis imperfecta (OI), commenced before three years of age.

METHODS

A retrospective review of 17 patients with moderate-to-severe OI. Development, anthropometry, fracture history, bone mineral density (BMD) and biochemistry were collected at baseline, 12 and 24 months.

RESULTS

Four had OI type I, eleven had type III, one OI-FKBP10 type and one OI type V. Mean age at start of pamidronate was 14 ± 11 months. Pamidronate ranged from 6 to 12 mg/kg/year. No adverse reaction apart from fever and vomiting was noted. Long bone fracture decreased from a mean of 10.4/year to 1.2/year after 12 months and 1.4/year after 24 months (p = 0.02). Lumbar spine age- and height-matched BMD Z-scores increased (p < 0.005). Sixteen with vertebral compression fractures at baseline all showed improved vertebral shape (p < 0.001). Concavity index, likewise, improved (p < 0.005). Motor milestones compared to historical data show earlier attainment in rolling over, crawling, pulling to stand and walking independently but not sitting.

CONCLUSION

Cyclic intravenous pamidronate, started under 3 years of age in children with moderate-to-severe OI, was well tolerated and associated with an increase in lumbar spine BMD, reduced fracture frequency, vertebral remodelling and attainment of motor milestones at an earlier age.

The use of bisphosphonates in children: review of the literature and guidelines for dental management

Bisphosphonates are inhibitors of osteoclastic bone resorption with therapeutic benefit in a variety of bone disorders in both adults and children. While these agents have been routinely used in adults for the past three decades, their more recent introduction into paediatric medicine means there is a paucity of data on long-term safety and effects on dental development. There is uncertainty regarding the dental management of children treated with bisphosphonates, particularly when invasive dental procedures, such as extractions and oral surgical procedures, are required. There are limited data with which to make recommendations about the dental management of patients treated with bisphosphonates, and there are no published recommendations that specifically address paediatric patients. This paper aims to outline paediatric uses and adverse effects of bisphosphonates and present recommendations on the dental management of children receiving bisphosphonates.

The effect of whole body vibration exposure on muscle function in children with cystic fibrosis: a pilot efficacy trial

Background

To examine the effects of whole body vibration (WBV) exposure on muscle function in children with Cystic Fibrosis (CF). Non-randomised controlled cross-over trial.

Methods

The setting was home-based WBV exposure. The participants were children (8 - 15 years) with CF (n = 7). Intervention: participants served as their own controls for the first four weeks (usual care), then underwent four weeks of parentally-supervised home-based WBV exposure followed by four weeks washout (usual care). The WBV exposure consisted of 20 - 30 minutes of intermittent (1 min vibration:1 min rest) exposure on a Galileo platform (20 - 22Hz, 1 mm amplitude) 3 days/week. The primary outcome measures of absolute and relative lower body (leg extension (LE), leg press (LP)), upper body (chess press (CP)) strength and power, and power were measured at baseline, and weeks 4, 8 and 12. Secondary exploratory outcomes were cardiorespiratory fitness, pulmonary function and health-related quality of life.

Results

Six participants completed the training without adverse events. Muscle function changes following WBV exposure were not statistically significant. However, moderate-to-large relative effect sizes (ES) favouring WBV were evident for leg extension strength (ES = 0.66 (-0.50, 1.82)), LP relative strength (ES = 0.92 (-0.27, 2.11)), leg press peak power (ES = 0.78 (-0.50, 2.07)) and CMJ height (ES = 0.60 (-0.56 to 1.76)).

Conclusions

The results from this first controlled trial indicate that WBV may be a potentially effective exercise modality to safely increase leg strength and explosive power in children with CF. Potentially clinically relevant changes support continued investigation of the efficacy, mechanism and feasibility of this intervention in future large-scale studies.

The successful use of pamidronate in an 11-year-old girl with complex regional pain syndrome: response to treatment demonstrated by serial peripheral quantitative computerised tomographic scans

Complex regional pain syndrome (CRPS) is a disorder that can cause significant functional morbidity. While it usually presents in adulthood, it has also been reported in children. Multiple treatment modalities have been reported with mixed success. Bisphosphonate therapy has been shown to be effective in adult patients, but there are limited data in children. We report the successful use of intravenous pamidronate therapy in diminishing pain, improving function, and restoring bone mass in an 11-year-old girl with CRPS of her left lower limb following a tibial fracture. Previous treatment with intense physiotherapy and regional sympathetic blockade had not improved her symptoms. Pain improved within weeks of the first pamidronate infusion, with subsequent improvement in function. The benefit in pain reduction and function was sustained during the 2-year treatment regime. Improvement in bone mass and density was demonstrated by dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computerised tomography (pQCT). pQCT scans showed marked improvement in bone size and geometry and muscle bulk on the affected side. No adverse affects were reported. We conclude that intravenous pamidronate was associated with reduced pain, a return of function, and recovery of bone and muscle parameters in a child with CRPS. Before definitive conclusions can be drawn, a randomised controlled trial similar to those undertaken in adults previously is required to fully validate this approach.

Prevention and treatment of osteoporosis in chronically ill children

Osteoporosis secondary to chronic disease in children has emerged as a major health issue. As the severity of a child's illness increases, so too does the number of factors affecting their bone health. Determinants of bone health in children include level of mobility, exposure to osteotoxic medication, nutritional status, calcium and vitamin D intake, chronic inflammation and pubertal development.

Histopathological analysis of Leri-Weill dyschondrosteosis: disordered growth plate

Leri-Weill syndrome (LWS) is a dominant (pseudoautosomal) skeletal dysplasia with mesomelic short stature and bilateral Madelung deformity, due to dyschondrosteosis of the distal radius. It results from the loss of one copy of the Short Stature Homeobox Gene (SHOX) from the tip of the short arm of the X or Y chromosome. SHOX molecular testing enabled us to evaluate the histopathology of the radial physis in LWS patients with a documented SHOX abnormality. A widespread disorganisation of physeal anatomy was revealed with disruption of the normal parallel columnar arrangement of chondrocytes. Tandem stacking of maturing chondrocytes within columns was replaced by a side-by-side arrangement. The presence of hypertrophic osteoid with micro-enchondromata in the radial metaphysis suggests abnormal endochondral ossification. The Vickers' ligament was confirmed to blend with the triangular fibrocartilage complex (TFCC). This histopathological study demonstrates that the zone of dyschondrosteosis in LWS is characterised by marked disruption of normal physeal chondrocyte processes and that a generalised physeal abnormality is present.

Height discordance in monozygotic females is not attributable to discordant inactivation of X-linked stature determining genes

We tested the hypothesis that X-linked genes determining stature which are subject to skewed or non-random X-inactivation can account for discordance in height in monozygotic female twins. Height discordant female monozygotic adult twins (20 pairs) were identified from the Australian Twin Registry, employing the selection criteria of proven monozygosity and a measured height discordance of at least 5 cm. Differential X-inactivation was examined in genomic DNA extracted from peripheral lymphocytes by estimating differential methylation of alleles at the polymorphic CAG triplet repeat of the Androgen receptor gene (XAR). There were 17/20 MZ pairs heterozygous at this locus and informative for analysis. Of these, 10/17 both had random X-inactivation, 5/17 showed identical X-inactivation patterns of non random inactivation and 2/17 (12%) showed discordant X-inactivation. There was no relationship between inactivation patterns and self-report chorionicity. We conclude that non-random X-inactivation does not appear to be a major contributor to intra-pair height discordance in female MZ twins.

Hepatic glycogenosis: reversible hepatomegaly in type 1 diabetes

OBJECTIVE

To describe the aetiology, clinical features and appropriate treatment for hepatic glycogenosis in poorly controlled type 1 diabetes.

METHODS

A review of three adolescents with poor diabetes control, hepatomegaly and elevated serum liver transaminase concentrations.

RESULTS

Symptoms included abdominal pain, anorexia, nausea and vomiting. All had tender hepatomegaly; two had splenomegaly. Liver biopsy was performed on two patients. Histology revealed hepatic glycogenosis in both; one also demonstrated macrovesicular steatosis. With improved glycaemic control, all three showed resolution of their symptoms, organomegaly and elevated serum liver transaminase concentrations.

CONCLUSIONS

Insulin-reversible hepatic glycogenosis is the most common cause of hepatomegaly and raised serum liver transaminase concentrations in children and adolescents with type 1 diabetes. Having excluded other causes of hepatic dysfunction, a 4 week therapeutic trial of improved glycaemic control is recommended prior to more invasive investigations.