Vitamin D and skeletal health in infancy and childhood

The effect of vitamin D on the speed and quality of pediatric fracture healing

Purpose

To evaluate the effect of vitamin D on the speed and quality of pediatric fracture healing.

Methods

A 4-year prospective study of healthy children with shaft fractures of the forearm bones (treated with minimally invasive osteosynthesis) or femur (treated by traction or by minimally invasive osteosynthesis). All children had their vitamin D levels examined four times-at the time of the injury, 1, 3, and 5 months after the injury. Also, all children underwent radiograph follow-ups (same time as blood tests) to evaluate fracture healing. Children were, in the beginning, blindly divided into two similarly sized groups-one group was orally administered cholecalciferol throughout the follow-up, the second group was not, and we compared those groups.

Results

Altogether, 63 children were included in the study-36 supplemented and 27 non-supplemented. In supplemented children, the vitamin D levels increased statistically significantly during the follow-up period, in contrast to the non-supplemented group. The fracture healing on radiographs was also statistically significantly faster and better in the supplemented group. When we divided children according to fracture type, we observed statistically significantly better fracture healing in children with forearm fractures in the supplemented group for the whole study period. In children with femoral fractures, the healing in the supplemented group was statistically significantly better after 3 months; however, after 1 and 5 months, the difference was not statistically significant.

Conclusions

Based on our results, we recommend vitamin D testing and administration for children treated for forearm and femoral fractures.

Level of evidence

Level I.

Vitamin D Levels During Fracture Healing in Children

To evaluate vitamin D levels in children treated with fractures during the healing period. A four-year prospective study, including healthy children treated with diaphyseal fracture of femur or forearm bones. Vitamin D levels were examined four times: at the time of the injury and then one, three, and five months after the injury, together with P1NP, ALP, GGT, and parathormone. In the beginning, patients were blindly divided into two groups, one supplemented with vitamin D3 for the entire follow-up period, the other non-supplemented. Altogether, 107 children underwent examination at the time of their injuries. Of these, 63 were included in the study and examined for the entire follow-up period - 36 supplemented, 27 non-supplemented. At the time of injury, 42 % had a deficit of vitamin D, 36.5 % had insufficiency, only 21.5 % had normal levels. In the children supplemented with cholecalciferol, vitamin D levels increased statistically significantly during the follow-up period (already after 1 month), in contrast with non-supplemented patients, where they did not. When we divided patients according to the initial vitamin D levels (deficit/insufficiency/normal levels) or fracture type (femur/forearm), we also observed significantly better results in supplemented groups. We observed a high prevalence of vitamin D deficit or insufficiency in healthy children at the time of their injuries. Patients supplemented with vitamin D3 had normal levels already after one month and this persisted throughout the follow-up period, in contrast with non-supplemented patients. Therefore, we recommend vitamin D testing and administration for children treated for fractures. Keywords: Vitamin D, Pediatric fracture, Children, Vitamin D supplementation.

Longitudinal analysis of vitamin D levels considering sunshine duration and suggestion for a standardised approach for vitamin D supplementation in children and adolescents with obesity

BACKGROUND

Children with obesity have low 25 hydroxy-vitamin D (25-OH-D3) levels compared to lean children. Recommendations on when to start vitamin D supplementation differ largely between countries. Longitudinal data on 25-OH-D3 levels to guide treatment decisions are scarce since they are largely influenced by solar radiation and are difficult to compare.

METHODS

We carried out a retrospective analysis of multiple 25-OH-D3 and parathyroid hormone (PTH) measurements in a cohort of 543 patients without vitamin D supplementation. All measurements were taken at the local paediatric obesity clinic as documented in the German-Austrian-Swiss APV (Prospective Documentation of Overweight Children and Adolescents) registry from 2009 to 2019. Serial 25-OH-D3 and PTH levels were adjusted for sunshine duration over the last 30 days to account for seasonal variation, as well as for sex and body mass index (BMI). We further performed an exploratory analysis of the association of sunshine duration, sex, BMI SDS (standard deviation score), abnormal lipid levels or dysglycemia with the 25-OH-D3 trend.

RESULTS

229 obese patients (mean BMI SDS: 2,58 (± 0,56), 53% females, mean age: 12 (± 3) years, range: 2-21 years) with two, 115 with three and 96 with four repeated 25-OH-D3 measurements were identified. Mean adjusted 25-OH-D3 (48.2 nmol/l) and PTH (34.9 ng/l) levels remained stable over 120 weeks. 5% of the patients had an elevated PTH > 65 ng/l. High total cholesterol ≥ 200 mg/dl and high triglycerides ≥ 130 mg/dl were associated with higher 25-OH-D3 levels.

CONCLUSION

We propose a simple method to include sunshine duration in the analysis of 25-OH-D3 levels to minimise the bias of seasonal variation. Based on our data we established the pragmatic strategy of limiting vitamin D supplementation to patients with biochemical signs of mineralisation disorders such as elevated PTH and alkaline phosphatase (AP). In children with normal PTH and AP we recommend adjustment of calcium intake and increase of outdoor activity instead.

Vitamin D supplements for fracture prevention in schoolchildren in Mongolia: analysis of secondary outcomes from a multicentre, double-blind, randomised, placebo-controlled trial

BACKGROUND

Vitamin D supplementation has been shown to increase total hip areal bone mineral density in healthy children and adolescents. We aimed to investigate whether supplementing schoolchildren living in Mongolia with weekly vitamin D3 for 3 years affected fracture risk.

METHODS

We did a multicentre, double-blind, randomised, placebo-controlled trial across 18 public schools in Ulaanbaatar, Mongolia. Schoolchildren were eligible if they were aged 6-13 years at screening, had a negative QuantiFERON-TB Gold In-tube assay (QFT) result, were not hypersensitive to vitamin D or immunocompromised, did not use vitamin D supplements, did not have clinical signs of rickets, and had no intention of leaving Ulaanbaatar within 3 years. Participants were randomly assigned (1:1) to receive either vitamin D (oral dose of 14 000 international units [IU] vitamin D3, once per week) or placebo for 3 years using permuted block randomisation stratified by school of attendance. Participants, care providers, and all trial staff were masked to group assignment during the intervention. Prespecified secondary outcomes were incidence of fractures and adverse events, ascertained using questionnaires. The fracture and safety analyses included participants who completed at least one follow-up fracture questionnaire. We estimated adjusted risk ratios (RRs) and 95% CIs using generalised linear models with binomial distribution and a log link function with adjustment for school of attendance. The trial is registered with ClinicalTrials.gov, NCT02276755, and the intervention ended in May, 2019.

FINDINGS

Between Sept 2, 2015, and March 20, 2017, 11 475 children were invited to participate in the study and 8851 were recruited and randomly assigned to receive either vitamin D (n=4418) or placebo (n=4433). 8348 participants were included in the fracture and safety analyses (4176 [94·5%] in the vitamin D group and 4172 [94·1%] in the placebo group). Of these, 4125 (49·4%) were female, 4223 (50·6%) were male, and 7701 (92·2%) were of Khalkh ancestry. Median age was 9·2 years (IQR 8·0-10·7) and 7975 (95·5%) participants had baseline serum 25-hydroxyvitamin D concentrations less than 50 nmol/L. During a median follow-up of 3·0 years (IQR 2·9-3·1), 268 (6·4%) participants in the vitamin D group and 253 (6·1%) in the placebo group reported one or more fractures (adjusted RR 1·10, 95% CI 0·93-1·29; p=0·27). Incidence of adverse events did not differ between study groups.

INTERPRETATION

Oral vitamin D supplementation at a dose of 14 000 IU/week for 3 years was safe, but did not influence fracture risk in schoolchildren living in Mongolia who had a high baseline prevalence of vitamin D deficiency.

FUNDING

US National Institutes of Health.

Early Life Programming of Skeletal Health

PURPOSE OF REVIEW

Increasing bone mineral accrual during childhood might delay the onset of osteoporosis. We discuss the scientific evidence for early life approaches to optimising skeletal health.

RECENT FINDINGS

There is an ever-growing body of evidence from observational studies suggesting associations between early life exposures, particularly during foetal development, and bone mineral density (BMD). The findings of such studies are often heterogeneous, and for some exposures, for example, maternal smoking and alcohol intake in pregnancy or age at conception, intervention studies are not feasible. The most frequently studied exposures in intervention studies are calcium or vitamin D supplementation in pregnancy, which overall suggest positive effects on offspring childhood BMD. Maternal calcium and/or vitamin D supplementation during pregnancy appear to have positive effects on offspring BMD during early childhood, but further long-term follow-up is required to demonstrate persistence of the effect into later life.

Influence of vitamin D supplementation on fracture risk, bone mineral density and bone biochemistry in Mongolian schoolchildren: multicenter double-blind randomized placebo-controlled trial

Background

Randomized controlled trials (RCT) of vitamin D supplementation to reduce fracture risk in children are lacking.

Methods

We conducted a Phase 3 RCT of weekly oral supplementation with 14,000 IU vitamin D3 for 3 years in Mongolian schoolchildren aged 6-13 years. Serum 25-hydroxyvitamin D (25[OH]D) concentrations and the proportion of participants reporting ≥1 fracture were secondary outcomes for the main trial. Radial bone mineral density (BMD) was assessed in a nested sub-study, with serum concentrations of parathyroid hormone (PTH) and bone-specific alkaline phosphatase (BALP) determined in a subset of participants.

Findings

8851 children were enrolled in the main trial, of whom 1465 also participated in the sub-study. Vitamin D deficiency was prevalent at baseline (25[OH]D <20 ng/mL in 90.1%). The intervention elevated 25(OH)D concentrations (adjusted inter-arm mean difference [aMD] 20.3 ng/mL, 95% CI 19.9 to 20.6) and suppressed PTH concentrations (aMD -13.6 pmol/L, 95% CI -23.5 to -3.7), but it did not influence fracture risk (adjusted risk ratio 1.10, 95% CI 0.93 to 1.29, P=0.27) or radial BMD z-score (aMD -0.06, 95% CI -0.18 to 0.07, P=0.36). Vitamin D suppressed serum BALP concentrations more among participants with baseline 25(OH)D concentrations <10 vs. ≥10 ng/mL (Pinteraction=0.04). However, effects of the intervention on fracture risk and radial BMD were not modified by baseline vitamin D status (Pinteraction≥0.67).

Interpretation

Weekly oral vitamin D supplementation elevated serum 25(OH)D concentrations and suppressed PTH concentrations in vitamin D-deficient schoolchildren in Mongolia. However, this was not associated with reduced fracture risk or increased radial BMD.

Funding

National Institutes of Health.

Spinal Fusion in Pediatric Patients With Low Bone Density: Defining the Value of DXA

BACKGROUND

Children with medical complexity are at increased risk of low bone mineral density (BMD) and complications after spinal fusion compared with idiopathic scoliosis patients. Our aim was to compare treatments and outcomes of children with medical complexity undergoing spinal fusion in those who had dual-energy x-ray absorptiometry (DXA) scans versus those who did not in an effort to standardize the workup of these patients before undergoing spinal surgery.

METHODS

We conducted a retrospective review of patients with low BMD who underwent spinal fusion at a tertiary care pediatric hospital between 2004 and 2016. We consulted with a pediatric endocrinologist to create standard definitions for low BMD to classify each subject. Regardless of DXA status, all patients were given a clinical diagnosis of osteoporosis [at least 2 long bone or 1 vertebral pathologic fracture(s)], osteopenia (stated on radiograph or by the physician), or clinically low bone density belonging to neither category. The last classification was used for patients whose clinicians had documented low bone density not meeting the criteria for osteoporosis or osteopenia. Fifty-nine patients met the criteria, and 314 were excluded for insufficient follow-up and/or not meeting a diagnosis definition. BMD Z -scores compare bone density ascertained by DXA to an age-matched and sex-matched average. Patients who had a DXA scan were also given a DXA diagnosis of low bone density (≤-2 SD), slightly low bone density (-1.0 to -1.9 SD), or neither (>-1.0 SD) based on the lowest BMD Z -score recorded.

RESULTS

Fifty-nine patients were analyzed. Fifty-four percent had at least 1 DXA scan preoperatively. Eighty-one percent of DXA patients received some form of treatment compared with 52% of non-DXA patients ( P =0.03).

CONCLUSIONS

Patients referred for DXA scans were more likely to be treated for low BMD, although there is no standardized system in place to determine which patients should get scans. Our research highlights the need to implement clinical protocols to optimize bone health preoperatively.

LEVEL OF EVIDENCE

Level II-retrospective prognostic study.

Pregnancy Vitamin D Supplementation and Childhood Bone Mass at Age 4 Years: Findings From the Maternal Vitamin D Osteoporosis Study (MAVIDOS) Randomized Controlled Trial

In the Maternal Vitamin D Osteoporosis Study (MAVIDOS) randomized trial, vitamin D supplementation in pregnancy did not lead to greater neonatal bone mass across the trial as a whole, but, in a prespecified secondary analysis by season of birth, led to greater neonatal bone mass among winter-born babies. Demonstrating persistence of this effect into childhood would increase confidence in a long-term benefit of this intervention. We investigated whether antenatal vitamin D supplementation increases offspring bone mineralization in early childhood in a prespecified, single-center follow-up of a double-blinded, multicenter, randomized controlled clinical trial based in the UK (MAVIDOS). A total of 1123 women in early pregnancy with a baseline 25-hydroxyvitamin D level 25-100 nmol/L from three research centers (2008-2014) were randomized to 1000 IU/d cholecalciferol or matched placebo from 14 weeks of gestation to delivery. Offspring born at the Southampton, UK research center were assessed at age 4 years (2013-2018). Anthropometry and dual-energy X-ray absorptiometry (DXA) were performed (yielding whole body less head [WBLH] bone mineral content [BMC], areal bone mineral density [aBMD], bone area [BA], and body composition). Of 723 children, 564 (78.0%) children attended the 4-year visit, 452 of whom had a useable DXA. Maternal vitamin D supplementation led to greater WBLH aBMD in the children compared with placebo (mean [95% confidence interval {CI}]: supplemented group: 0.477 (95% CI, 0.472-0.481) g/cm2; placebo group: 0.470 (95% CI, 0.466-0.475) g/cm2, p = 0.048). Associations were consistent for BMC and lean mass, and in age- and sex-adjusted models. Effects were observed across the whole cohort irrespective of season of birth. Maternal-child interactions were observed, with a greater effect size among children with low milk intake and low levels of physical activity. Child weight, height, and body mass index (BMI) were similar by maternal randomization group. These findings suggest a sustained beneficial effect of maternal vitamin D supplementation in pregnancy on offspring aBMD at age 4 years, but will require replication in other trials. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Hepatic Steatosis is Negatively Associated with Bone Mineral Density in Children

OBJECTIVE

To evaluate the relationship between hepatic steatosis and bone mineral density (BMD) in children. In addition, to assess 25-hydroxyvitamin D levels in the relationship between hepatic steatosis and BMD.

STUDY DESIGN

A community-based sample of 235 children was assessed for hepatic steatosis, BMD, and serum 25-hydroxyvitamin D. Hepatic steatosis was measured by liver magnetic resonance imaging proton density fat fraction (MRI-PDFF). BMD was measured by whole-body dual-energy x-ray absorptiometry.

RESULTS

The mean age of the study population was 12.5 years (SD 2.5 years). Liver MRI-PDFF ranged from 1.1% to 40.1% with a mean of 9.3% (SD 8.5%). Across this broad spectrum of hepatic fat content, there was a significant negative relationship between liver MRI-PDFF and BMD z score (R = -0.421, P < .001). Across the states of sufficiency, insufficiency, and deficiency, there was a significant negative association between 25-hydroxyvitamin D and liver MRI-PDFF (P < .05); however, there was no significant association between vitamin D status and BMD z score (P = .94). Finally, children with clinically low BMD z scores were found to have higher alanine aminotransferase (P < .05) and gamma-glutamyl transferase (P < .05) levels compared with children with normal BMD z scores.

CONCLUSIONS

Across the full range of liver MRI-PDFF, there was a strong negative relationship between hepatic steatosis and BMD z score. Given the prevalence of nonalcoholic fatty liver disease and the critical importance of childhood bone mineralization in protecting against osteoporosis, clinicians should prioritize supporting bone development in children with nonalcoholic fatty liver disease.

Effect of Vitamin D Supplementation in Early Life on Children's Growth and Body Composition: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Vitamin D deficiency during pregnancy or infancy is associated with adverse growth in children. No systematic review has been conducted to summarize available evidence on the effect of vitamin D supplementation in pregnancy and infancy on growth and body composition in children. Objective: We aim to summarize the available evidence on the effect of vitamin D supplementation in pregnancy and infancy on child growth and body composition. Method: A systematic review and meta-analysis were performed on the effects of vitamin D supplementation during early life on children’s growth and body composition (bone, lean and fat). A literature search of randomized controlled trials (RCTs) was conducted to identify relevant studies on the effects of vitamin D supplementation during pregnancy and infancy on children’s body composition (bone, lean and fat) in PubMed, EMBASE and Cochrane Library from inception to 31 December 2020. A Cochrane Risk Assessment Tool was used for quality assessment. The comparison was vitamin D supplementation vs. placebo or standard care. Random-effects and fixed-effect meta-analyses were conducted. The effects are presented as mean differences (MDs) or risk ratios (RRs) with 95% confidence intervals (CIs). Results: A total of 3960 participants from eleven randomized controlled trials were eligible for inclusion. Vitamin D supplementation during pregnancy was associated with higher triceps skinfold thickness (mm) (MD 0.33, 95% CI, 0.12, 0.54; I² = 34%) in neonates. Vitamin D supplementation during pregnancy or infancy was associated with significantly increased length for age z-score in infants at 1 year of age (MD 0.29, 95% CI, 0.03, 0.54; I² = 0%), and was associated with lower body mass index (BMI) (kg/m²) (MD −0.19, 95% CI −0.34, −0.04; I² = 0%) and body mass index z-score (BMIZ) (MD −0.12, 95% CI −0.21, −0.04; I² = 0%) in offspring at 3–6 years of age. Vitamin D supplementation during early life was not observed to be associated with children’s bone, lean or fat mass. Conclusion: Vitamin D supplementation during pregnancy or infancy may be associated with reduced adiposity in childhood. Further large clinical trials of the effects of vitamin D supplementation on childhood body composition are warranted.

Vitamin D Status in Children With Forearm Fractures: Incidence and Risk Factors

Introduction:

The association between vitamin D status and fracture characteristics in children remains ambiguous. We hypothesized that vitamin D deficient or insufficient children would have an increased risk of forearm fractures severe enough to require surgical management.

Methods:

One hundred children with low-energy forearm fractures were prospectively enrolled from a single hospital. Each participant answered a questionnaire focusing on the risk factors for vitamin D deficiency. Fractures were categorized as requiring nonsurgical or surgical management. Vitamin D status was based on the measurement of 25-hydroxyvitamin D (25(OH)D) concentration obtained during the clinic visit and compared between the two fracture groups.

Results:

The cohort exhibited a mean age of 9.8 ± 3.2 years (range: 3-15 years), comprising 65 (65%) men and 35 (35%) women. Overall, mean 25(OH)D was 27.5 ± 8.3 ng/mL. Using the Endocrine Society guidelines, 21% of patients were categorized as “vitamin D deficient” (25(OH)D ≤ 20 ng/mL) and 49% as “vitamin D insufficient” (25(OH)D: 21 to 29 ng/mL). Stratification by intervention revealed a mean 25(OH)D of 23.3 ± 8.8 ng/mL in the surgical group (n = 12) and 28.1 ± 8.1 in the nonsurgical group (n = 88) (P = 0.057). Fifty percent of the surgical group were “vitamin D deficient” compared with 17% of the nonsurgical group (P = 0.017). The relative risk of requiring surgical treatment in children with forearm fracture and vitamin D deficiency (25(OH)D < 20 ng/mL) was 3.8. 25(OH)D level, negatively correlated with body mass index (r = −0.21, P = 0.044); 9 surgical patients were overweight or obese (as defined by the criteria of the Centers for Disease Control and Prevention). 25(OH)D level was significantly lower in non-Caucasians compared with Caucasians (26.0 ± 7.2 versus 32.5 ± 9.9 ng/mL; P = 0.0008).

Discussion:

Vitamin D deficiency is common in children with forearm fractures and may be a contributing risk factor for forearm fractures requiring surgical management in children.

Conclusion:

Vitamin D deficiency and inefficiency are common in children with low energy forearm fractures, especially in obese children and in fractures requiring surgical treatment.

Vitamin D and bone health in adults: a systematic review and meta-analysis

Low bone health is associated with vitamin D deficiency in older individuals; however, this association is not well established in adults. The aim of the study was to analyze the association between serum concentrations of 25-hydroxyvitamin D and bone health in adults by systematic review and meta-analysis. The search was carried out in the LILACS, PubMed, Scopus, Web of Science, ScienceDirect databases from March 2017 to October 2018 with adult individuals (20-59 years). Bone health was evaluation performed through dual X-ray absorptiometry and serum concentrations of 25(OH)D. The random effect model was used to analyze data from bone mineral content and bone mineral. Random effects models were used and the sources of heterogeneity were explored by means of meta-regression. Thirty-five articles were selected. There was positive correlation between vitamin D and bone health in most of the evaluated sites. Correlation was observed in the analysis of subgroups for lumbar spine among men. When stratified, the studies presented high heterogeneity, which was explained by the sample size, mean serum vitamin D levels and risk of bias. Vitamin D is positively correlated to bone health in adult individuals.

Vitamin D, and Maternal and Child Health

Vitamin D has important roles in calcium metabolism and in the prevention of rickets and osteomalacia; low levels of 25-hydroxyvitamin D are common in the general population and amongst pregnant women. Whilst there is a wealth of observational evidence linking vitamin D deficiency to a wide range of disease outcomes, there are currently few high-quality randomised controlled trials to confirm any causal associations, although many are currently in progress. Furthermore, currently, the vast majority of published guidelines recommend standard supplemental vitamin D doses for children and pregnant women, yet there is increasing recognition that individual characteristics and genetic factors may influence the response to supplementation. As such, future research needs to concentrate on documenting definite beneficial clinical outcomes of vitamin D supplementation, and establishing personalised dosing schedules and demonstrating effective approaches to optimising initiation and adherence.

Vitamin D status among preterm infants with cholestasis and metabolic bone disease

BACKGROUND

Metabolic bone disease of prematurity (MBD) is a common problem among preterm infants. Our previous study identified cholestasis as an important risk factor for the development of MBD. We conducted this study to determine the vitamin D status in preterm infants with MBD and cholestasis.

METHODS

We retrospectively reviewed medical record of preterm infants evaluated in NICU at Holtz Children's/Jackson Memorial Hospital between June 2014 and May 2016. Demographic, biochemical data, and vitamin D intake were collected and analyzed.

RESULTS

We identified 58 preterm infants (median gestational age 25 weeks) with MBD during this period. Twenty five infants also developed cholestasis. Median serum 25-hydroxyvitamin D level at the time of diagnosis of MBD was similar in cholestasis (C), (29.1 ng/ml, IQR 24.4-33.5), and non-cholestasis (NC), (28.7 ng/ml, IQR 22.7-34.6), group (p = 0.41). At the second measurement, average 6 weeks after the first measurement; median serum 25-hydroxyvitamin D level was lower (p = 0.02) in the C group (31.2 ng/ml, IQR 23.0-38.8) than in the NC group (36.5 ng/ml, IQR 28-45). However, the actual percentage of infants with vitamin D deficiency was similar in both the groups.

CONCLUSION

Most preterm infants with cholestasis and MBD had normal vitamin D status.

Population-based register study of children born in Sweden from 1997 to 2014 showed an increase in rickets during infancy

AIM

This population-based study assessed the incidence of rickets in infants up to age of one born in Sweden from 1997 to 2014. We also examined maternal and perinatal factors and co-morbidity.

METHODS

We used Swedish National Board of Health and Welfare registers and data from Statistics Sweden. The outcome measure was an International Classification of Diseases, Tenth Revision, code for rickets.

RESULTS

There were 273 cases of rickets, with an incidence of 14.7 per 100 000 and a 10-fold incidence increase between 1997 and 2014. The majority (78.4%) were born preterm, half were small-for-gestational age (SGA) (birthweight <10th percentile), 4.8% were born to Asian-born mothers and 3.5% to African-born mothers. The adjusted odds ratios by birth week were 182 (95% CI: 121-272) before 32 weeks and 10.8 (95% CI: 6.72-17.4) by 32-36 weeks. Preterm infants with necrotising enterocolitis had very high odds for rickets and so did SGA term-born infants and those born to African-born mothers. The odds for rickets among preterm infants increased considerably during the later years.

CONCLUSION

Rickets increased 10-fold in Sweden from 1997 to 2014 and was mainly associated with prematurity, SGA and foreign-born mothers. Possible reasons may include increased preterm survival rates and improved clinical detection and registration.

Determinants for low bone mineral density in pre-school children: a matched case-control study in Wuhan, China

Introduction Reduced bone mass will increase bone fragility and risk of fractures. Thus, it is better to note its determinants as early as possible. Objective This study aimed to find and determine the determinants for low bone mineral density (BMD) in pre-school children. Methods Between November 2014 and April 2015, a matched case-control study was performed to detect information on growth and development condition and consumption frequency of products of cases with low BMD and controls with normal BMD. Anthropometric data measurement and blood tests were conducted. Besides, the questionnaires concerning the mentioned information were completed to get relevant determinants. A paired t-test, the McNemar test and univariate and multiple conditional logistic regression models were used to explore the association between these factors and low BMD. Results In total, 88 (28 boys, 60 girls) incident cases (4.15 ± 0.78 years) of low BMD and 88 sex- and age-matched (±2 months) controls (4.16 ± 0.80 years) of normal BMD were enrolled. The results of multiple conditional logistic regression analysis indicated that if children had larger chest circumference (odds ratio [OR] = 0.763), longer duration of breastfeeding (OR = 0.899) and lower frequency of eating snacks (OR = 0.439), the risk of low BMD would decrease. Conclusions Our findings suggest that pre-school children with an association of larger chest circumference, longer duration of breastfeeding and lower frequency of eating snacks could have lower risk for low BMD. Intended measures to strengthen those protective factors could be effective in reducing the cases of low BMD.

An epidemiological evaluation of fractures and its determinants among Lebanese schoolchildren: a cross-sectional study

The purpose of this study is to establish the prevalence and determinants of fractures among 974 Lebanese schoolchildren aged 8-18. Fractures might be less common in the Lebanese pediatric population compared to western populations. Male gender and high SES are independent risk factors for fractures, while 25(OH)D and BMI have no impact.

PURPOSE

To establish the prevalence of fractures among Lebanese schoolchildren and its relationship with age, gender, BMI, 25 hydroxyvitamin D (25(OH)D) levels, and socioeconomic status (SES).

METHODS

In this cross-sectional study, 974 Lebanese schoolchildren aged 8-18 years old, mean age 13.37 ± 2.92 (508 boys and 466 girls), were recruited from 10 schools with different SES. For each participant, a questionnaire was used to collect data regarding history of fractures. Serum 25(OH)D was also measured.

RESULTS

The prevalence of Lebanese children sustaining ≥ 1 fracture was 16.9% and was higher in boys compared to girls (22.2% vs 11.1%, p < 0.0001). A 71.3% of fractures were localized in the upper limbs and 20% of participants had at least one displaced fracture. Children who sustained a fracture had a non-significant higher BMI compared to those without (p = 0.096). The percentage of children with fractures was higher in children from high SES compared to those from middle and low SES (respectively 23.3% vs. 16.3% and 13.8%, p < 0.0001). Fractures occurred at a younger age in girls compared to boys, but this difference was non-significant (p = 0.13). 25(OH)D levels were significantly higher in children with fractures compared to those without (p = 0.017). Finally, female gender was protective against upper limb fractures (p = 0.009). In a logistic regression analysis, male gender and high SES were independently associated with fractures, while BMI and 25(OH)D were not.

CONCLUSION

Our study demonstrates that the prevalence of fractures in the Lebanese pediatric population might be lower than western populations. It also confirms that male gender and high SES are independent risk factors for fractures, while 25(OH)D and BMI were not independently associated with fracture risk.

Vitamin D Deficiency: The Missing Etiological Factor in the Development of Juvenile Osteochondrosis Dissecans?

BACKGROUND

Vitamin D deficiency can result in rickets and hypocalcemia during infant and childhood growth. There is an increasing interest in the role of vitamin D with regards to childhood bone health. Osteochondrosis dissecans (OD) is a common disease affecting different joints. To date, the exact etiology of OD still remains unclear. The aim of this study was to evaluate a possible association of vitamin D deficiency and juvenile OD.

METHODS

A retrospective chart review of the years 2010 to 2015 of all orthopaedic patients with an initial diagnosis of juvenile OD admitted to undergo operative treatment of the OD was performed. Patient demographics, medical history, information on sports activity (if available) and serum vitamin D (25-OH-D) level on admission date were obtained. For statistical comparison, we measured baseline prevalence of vitamin D insufficiency in age-matched orthopaedic patients presenting at the department of pediatric orthopaedics.

RESULTS

A total of 80 patients were included in this study. Overall, 97.5% (n=78) of tested patients in the OD group had serum vitamin D levels below the recommended threshold of 30 ng/mL (mean value of 10.1 ng/mL (±6.7 ng/mL)). Over 60% (n=49) were vitamin D deficient, 29 patients (37%) showed serum levels below 10 ng/mL corresponding to a severe vitamin D deficiency. Of note, only 2 patients (2.5%) reached serum vitamin D levels above the recommended threshold of 30 ng/mL. No statistical difference was found in respect to sports activity level before onset of the symptoms (P=0.09). Statistical analysis found a significant difference in vitamin D levels between patients with OD and patients without an OD (P=0.026).

CONCLUSIONS

We found an unexpected high prevalence of vitamin D deficiency in juveniles diagnosed with OD presenting with significant lower mean 25-OH-D level compared with a control group. These results suggest that vitamin D deficiency is potentially associated with the development of OD. Thus, vitamin D deficiency might be an important cofactor in the multifactorial development of juvenile OD. For this reason, supplementation of vitamin D might not only be a potential additional therapy but also be a possible preventative factor in patients with juvenile OD. However, future prospective studies are needed to confirm this preliminary data.

LEVEL OF EVIDENCE

Level III-this is a case-control study.

Rare paleopathological insights into vitamin D deficiency rickets, co-occurring illnesses, and documented cause of death in mid-19th century London, UK

Growing evidence suggests that vitamin D supports immune responses to infections, autoimmune conditions and cancers, although evidence from large-scale studies is limited. There is scope to better understand how vitamin D deficiency interacted with other diseases to affect health in past groups. This study investigated paleopathological evidence and documentary records of individual cause of death to examine disease co-occurrence in a group of mid-19th century child burials from London, UK. Twenty-one percent of children had vitamin D deficiency rickets (138/642) and 36 children with rickets had an identified cause of death. Cyclical episodes of metabolic and nutritional deficiencies (rickets and scurvy) had occurred during childhood. Active rickets co-occurred with respiratory and gastrointestinal infections in a small number of children, likely reflecting vitamin D's role in supporting immune function. Consideration of the stage of the vitamin D deficiency showed that the majority of children were affected by chronic disease loads indicative of multiple episodes of illness. Reconstructions of the wider health consequences of vitamin D deficiency in past groups are dependent on recognising whether the deficiency was active or healed. The variability of diseases identified illustrates the high disease burden that affected children in this socially disadvantaged group.

Vitamin D Intervention and Bone: A Randomized Clinical Trial in Fair- and Dark-skinned Children at Northern Latitudes

OBJECTIVES

The aim of the study was to evaluate vitamin D status and effects of vitamin D intervention on bone mineral density (BMD) and content (BMC) in children with fair and dark skin in Sweden during winter.

METHODS

In a 2-center prospective double-blinded randomized intervention study 5- to 7-year-old children (n = 206) with fair and dark skin in Sweden (55°N-63°N) received daily vitamin D supplements of 25 μg, 10 μg, or placebo (2 μg) during 3 winter months. We measured BMD and BMC for total body (TB), total body less head (TBLH), femoral neck (FN), and spine at baseline and 4 months later. Intake of vitamin D and calcium, serum 25-hydroxy vitamin D (S-25[OH]D), and related parameters were analyzed.

RESULTS

Despite lower S-25(OH)D in dark than fair-skinned children, BMD of TB (P = 0.012) and TBLH (P = 0.002) and BMC of TBLH (P = 0.04) were higher at baseline and follow-up in those with dark skin. Delta (Δ) BMD and BMC of TB and TBLH did not differ between intervention and placebo groups, but FN-BMC increased more among dark-skinned children in the 25 μg (P = 0.038) and 10 μg (P = 0.027) groups compared to placebo. We found no associations between Δ S-25(OH)D, P-parathyroid hormone, P-alkaline phosphatase, and Δ BMD and BMC, respectively.

CONCLUSIONS

BMD and BMC remained higher in dark- than fair-skinned children despite lower vitamin D status. Even though no difference in general was found in BMD or BMC after vitamin D intervention, the increase in FN-BMC in dark-skinned children may suggest an influence on bone in those with initially insufficient vitamin D status.

The Convergence of Two Epidemics: Vitamin D Deficiency in Obese School-aged Children

PROBLEM

Vitamin D deficiency (VDD) and obesity are two interrelated global epidemics that affect school-aged children. This article will review the relationship between VDD and obesity in school-aged children and implications it has for the pediatric nurse (PN).

ELIGIBILITY CRITERIA

Original articles of studies, review articles and meta-analyses were selected from the past 5years and pooled for review. These included obese school-aged children who had vitamin D insufficiency. The latest guidelines concerning the issue were also included.

SAMPLE

Children 6-12years of age with obesity and vitamin D insufficiency.

RESULTS

This review strongly implies obesity in children being a strong risk factor for VDD. Prevention of VDD starts with lifestyle changes and adequate dietary intake of fortified foods and current screening recommendations for VDD are inconsistent. Vitamin D supplementation is recommended with inadequate intake or deficient serum 25-hydroxyvitamin D levels or signs of hypocalcemia. Supplementation doses differ based on whether VDD is being prevented or being treated and in obese children, the Endocrine Society recommends a dose that is two to three times higher than for normal weight children. Subclinical signs and symptoms of VDD include musculoskeletal pain, fractures, reduced bone density and reduced immunity.

CONCLUSIONS

Whereas obesity is a strong risk factor for VDD, more research is needed to clarify the role of VDD as a risk factor for obesity.

IMPLICATIONS

The PN plays an essential role in preventing, screening for, assessing for, treating and counseling on VDD in obese school-aged children.

The effects of different intensities of exercise and active vitamin D on mouse bone mass and bone strength

Physical exercise is beneficial to bone health. However, little is known how different intensities of exercise affect bone mass and strength. In the present study, we used young mice to study the effects of different intensities of exercise on bone mass and bone strength in comparison to pharmacological doses of active vitamin D (calcitriol). We found that only the medium level of exercise tested showed a positive effect on bone mineral density, trabecular bone volume, and bone strength, which are attributable to a decrease in bone resorption and an increase in bone formation, with the latter being accompanied by an increase in the number of osteogenic mesenchymal stem cells in the bone marrow. Calcitriol increases bone volume and bone strength, yet the combination of calcitriol and medium-intensity exercise did not further improve bone mass or strength. Moreover, calcitriol also showed some protective effect on the bone in mice with high levels of exercise. These results indicate that exercise at medium intensity increases bone mass and strength via affecting both bone formation and resorption and that its beneficial effects on bone mass cannot be further improved by calcitriol.

Serum 25-hydroxyvitamin D status among Saudi children with and without a history of fracture

BACKGROUND

The significance of vitamin D deficiency in the incidence of bone fractures in children has been under investigated. Here, we aimed to associate serum 25-hydroxyvitamin D levels and fractures in Saudi children.

MATERIALS AND METHODS

This cross-sectional study was conducted in 1022 Saudi children without fracture history [476 boys (age 14.56 ± 1.81, BMI 22.38 ± 5.81) and 546 girls (age 13.57 ± 1.67, BMI 22.24 ± 4.94)] and 234 Saudi children with a history of fracture [148 boys (age 14.25 ± 1.39, BMI 22.66 ± 6.08) and 86 girls (age 13.76 ± 1.35, BMI 21.33 ± 1.35)]. Anthropometric and fasting serum biochemical data were collected. Serum 25-hydroxyvitamin D level was assessed using electrochemiluminescence.

RESULTS

Mean circulating 25-hydroxyvitamin (25OH) D level in subjects with a history of fracture was significantly lower in both boys (p < 0.01) and girls (p < 0.01) than those without, however both groups had low mean 25(OH)D levels. Furthermore, age was positively associated with 25-hydroxyvitamin D in boys (p < 0.05) and negatively in girls (p < 0.05) with a history of fracture.

CONCLUSION

In conclusion, vitamin D levels were significantly lower in children with a history of bone fractures in both boys and girls than those without such a history; even in the absence of fracture history, vitamin D status correction is warranted in the general Saudi pediatric population.

The etiology and significance of fractures in infants and young children: a critical multidisciplinary review

This paper addresses significant misconceptions regarding the etiology of fractures in infants and young children in cases of suspected child abuse. This consensus statement, supported by the Child Abuse Committee and endorsed by the Board of Directors of the Society for Pediatric Radiology, synthesizes the relevant scientific data distinguishing clinical, radiologic and laboratory findings of metabolic disease from findings in abusive injury. This paper discusses medically established epidemiology and etiologies of childhood fractures in infants and young children. The authors also review the body of evidence on the role of vitamin D in bone health and the relationship between vitamin D and fractures. Finally, the authors discuss how courts should properly assess, use, and limit medical evidence and medical opinion testimony in criminal and civil child abuse cases to accomplish optimal care and protection of the children in these cases.

Development, Epigenetics and Metabolic Programming

It is now widely recognized that the environment in early life can have important effects on human growth and development, including the 'programming' of far-reaching effects on the risk of developing common metabolic and other noncommunicable diseases in later life. We have shown that greater childhood adiposity is associated with higher maternal adiposity, low maternal vitamin D status, excessive gestational weight gain and short duration of breast-feeding; maternal dietary patterns in pregnancy and vitamin D status have been linked with childhood bone mineral content and muscle function. Human studies have identified fetal liver blood flow adaptations and epigenetic changes as potential mechanisms that could link maternal influences with offspring body composition. In experimental studies, there is now substantial evidence that the environment during early life induces altered phenotypes through epigenetic mechanisms. Epigenetic processes, such as DNA methylation, covalent modifications of histones and non-coding RNAs, can induce changes in gene expression without a change in DNA base sequence. Such processes are involved in cell differentiation and genomic imprinting, as well as the phenomenon of developmental plasticity in response to environmental influences. Elucidation of such epigenetic processes may enable early intervention strategies to improve early development and growth.

Ethnic and geographic variations in the epidemiology of childhood fractures in the United Kingdom

BACKGROUND

Fractures are common in childhood, and there is considerable variation in the reported incidence across European countries, but few data relating to ethnic and geographic differences within a single country. We therefore aimed to determine the incidence of childhood fractures in the United Kingdom (UK), and to describe age-, ethnicity- and region- specific variations.

METHODS

The Clinical Practice Research Datalink (CPRD) contains anonymised electronic health records for approximately 7% of the UK population. The occurrence of a fracture between 1988 and 2012 was determined from the CPRD for all individuals <18years of age, and used to calculate fracture incidence rates for age, sex and ethnicity. Regional fracture incidence rates were also calculated based on general practitioner location within 14 Strategic Health Authorities (SHA) within the UK.

RESULTS

The overall fracture incidence rate was 137 per 10,000 person-years (py). This was higher in boys (169 per 10,000 py) than girls (103 per 10,000 py) and white children (150 per 10,000 py) compared to those of black (64 per 10,000 py) and South Asian (81 per 10,000 py) ethnicity. Marked geographic variation in incidence was observed. The highest fracture rates were observed in Wales, where boys and girls had 1.82 and 1.97 times greater incidence, respectively, than those residing in Greater London.

CONCLUSION

In the period 1988-2012, there was marked geographic and ethnic variation in childhood fracture incidence across the UK. These findings also implicate lifestyle and socio-economic differences associated with location and ethnicity, and are relevant to policy makers in the UK and internationally.

Comparison of the Vitamin D Status of Children Younger and Older Than 2 Years in Tehran: Are Supplements Really Necessary?

BACKGROUND

Vitamin D is a vital lipid-soluble vitamin in the body, helping the growth and development of bones. Vitamin D deficiency in children has several adverse effects. The most important preventative factor is determining the deficiency at an early stage and prescribing vitamin D-containing supplements.

OBJECTIVES

To investigate the vitamin D status of children younger and older than 2 years and determine the utility of prescribing vitamin D supplements.

PATIENTS AND METHODS

Three hundred healthy children who attended the pediatric clinic for routine assessments were enrolled in this study. Their parents were asked to complete a questionnaire, which included questions about demographics, nutrition, and supplements. Blood levels of vitamin D, calcium, and phosphorus were then measured.

RESULTS

The final study consisted of 286 children, 140 males and 146 females, with a mean age of 4.46 ± 2.82 yr. Of these, 218 (76.22%) children, with a mean age of 5.09 ± 2.82 yr, had vitamin D deficiency, and 76 children (23.78%), with a mean age of 2.58 ± 1.88 yr, had normal vitamin D levels (P = 0.001). The mean level of vitamin D was 29.71 ± 14.42 ng/mL in 88 (30.8%) patients up to 2 years and 17.11 ± 14.02 ng/mL in 198 (69.2%) patients older than 2 years (P = 0.0001).

CONCLUSIONS

The vitamin D levels of children aged more than 2 years are lower than those of children aged less than 2 years. Thus, prescribing vitamin D-containing supplements in children older than 2 years may be beneficial.

Life-course approach to nutrition

This narrative review summarizes the role that nutrition plays in the development and maintenance of a healthy skeleton throughout the life-course. Nutrition has a significant influence on bone health throughout the life cycle. This narrative review summarizes current knowledge and guidance pertaining to the development and maintenance of a healthy skeleton. The primary objectives proposed for good bone health at the various stages of life are the following: Children and adolescents: achieve genetic potential for peak bone mass Adults: avoid premature bone loss and maintain a healthy skeleton Seniors: prevention and treatment of osteoporosis Findings from cohort studies, randomized controlled trials, systematic reviews and meta-analyses, in addition to current dietary guidelines, are summarized with the intention of providing clear nutritional guidance for these populations and pregnant women.

Differences in childhood adiposity influence upper limb fracture site

INTRODUCTION

Although it has been suggested that overweight and obese children have an increased risk of fracture, recent studies in post-menopausal women have shown that the relationship between obesity and fracture risk varies by fracture site. We therefore assessed whether adiposity and overweight/obesity prevalence differed by upper limb fracture site in children.

METHODS

Height, weight, BMI, triceps and subscapular skinfold thickness (SFT) were measured in children aged 3-18 years with an acute upper limb fracture. Data was compared across three fracture sites (hand, forearm and upper arm/shoulder [UA]), and to published reference data.

RESULTS

401 children (67.1% male, median age 11.71 years, range 3.54-17.27 years) participated. 34.2%, 50.6% and 15.2% had fractures of the hand, forearm and UA, respectively. Children with forearm fractures had higher weight, BMI, subscapular SFT and fat percentage z-scores than those with UA fractures (p<0.05 for all). SFT and fat percentage z-scores were also higher in children with forearm fractures compared to hand fractures, but children with hand and UA fractures did not differ. Overweight and obesity prevalence was higher in children with forearm fractures (37.6%) than those with UA fractures (19.0%, p=0.009). This prevalence was also higher than the published United Kingdom population prevalence (27.9%, p=0.003), whereas that of children with either UA (p=0.13) or hand fractures (29.1%, p=0.76) did not differ. These differences in anthropometry and overweight/obesity prevalence by fracture site were evident in boys, but not present in girls.

CONCLUSION

Measurements of adiposity and the prevalence of overweight/obesity differ by fracture site in children, and in particular boys, with upper limb fractures.

Association between bone stiffness and nutritional biomarkers combined with weight-bearing exercise, physical activity, and sedentary time in preadolescent children. A case-control study

Physical activity (PA) and micronutrients such as calcium (Ca), vitamin D (25OHD), and phosphate (PO) are important determinants of skeletal development. This case-control study examined the association of these nutritional biomarkers and different PA behaviours, such as habitual PA, weight-bearing exercise (WBE) and sedentary time (SED) with bone stiffness (SI) in 1819 2-9-year-old children from the IDEFICS study (2007-2008). SI was measured on the calcaneus using quantitative ultrasound. Serum and urine Ca and PO and serum 25OHD were determined. Children's sports activities were reported by parents using a standardised questionnaire. A subsample of 1089 children had accelerometer-based PA data (counts per minute, cpm). Moderate-to-vigorous PA (MVPA) and SED were estimated. Children with poor SI (below the 15th age-/sex-/height-specific percentile) were defined as cases (N=603). Randomly selected controls (N=1216) were matched by age, sex, and country. Odds ratios (OR) for poor SI were calculated by conditional logistic regression for all biomarkers and PA behaviour variables separately and combined (expressed as tertiles and dichotomised variables, respectively). ORs were adjusted for fat-free mass, dairy product consumption, and daylight duration. We observed increased ORs for no sports (OR=1.39, p<0.05), PA levels below 524 cpm (OR=1.85, p<0.05) and MVPA below 4.2% a day (OR=1.69, p<0.05) compared to WBE, high PA levels (<688 cpm) and high MVPA (6.7%), respectively. SED was not associated with SI. ORs were moderately elevated for low serum Ca and 25OHD. However, biomarkers were not statistically significantly associated with SI and did not modify the association between PA behaviours and SI. Although nutritional biomarkers appear to play a minor role compared to the osteogenic effect of PA and WBE, it is noteworthy that the highest risk for poor SI was observed for no sports or low MVPA combined with lower serum Ca (<2.5 mmol/l) or lower 25OHD (<43.0 nmol/l).

Vitamin D signaling in calcium and bone homeostasis: a delicate balance

Loss-of-function mutations in genes involved in the vitamin D/vitamin D receptor system have clearly evidenced its critical role for mineral and skeletal homeostasis. Adequate levels of 1,25-dihydroxyvitamin D [1,25(OH)2D], the active form of vitamin D are therefore required and depend on sufficient sunlight exposure or dietary intake. Intestinal calcium absorption is a primary target of 1,25(OH)2D action and this pathway indirectly promotes calcium incorporation in bone. Severe vitamin D deficiency may thus decrease bone quality and leads to osteomalacia, whereas less severe deficiency increases the risk of osteoporosis and bone fractures. On the other hand, high vitamin D levels together with low dietary calcium intake will increase bone resorption and decrease bone mineralization in order to maintain normal serum calcium levels. Appropriate dietary calcium intake and sufficient serum vitamin D levels are thus important for skeletal health. Dosing of calcium and vitamin D supplements is still debated and requires further investigation.

Serum 25-Hydroxyvitamin D Levels: Variability, Knowledge Gaps, and the Concept of a Desirable Range

Hypovitaminosis D is prevalent worldwide but proportions vary widely between regions, depending on genetic and lifestyle factors, the threshold to define deficiency, and accuracy of 25-hydroxyvitamin D (25OHD) assays used. Latitude, pollution, concealing clothing, sun exposure, gender, dietary habits, and lack of government regulation account for up to 50% in variations in serum 25OHD levels, whereas genetic polymorphisms in the vitamin D pathway account for less than 5%. Organizations/societies have developed guidelines for recommended desirable 25OHD levels and vitamin D doses to reach them, but their applicability across age groups and populations are still debated. This article and the accompanying online Supporting Information highlight sources of variations in circulating 25OHD levels, uncertainties and knowledge gaps, and analytical problems facing 25OHD assays, while keeping efficacy and safety data as the dominant factors when defining a desirable range for 25OHD levels. We propose a desirable range of 20 to 40 ng/mL (50 to 100 nmol/L), provided precise and accurate assays are used. Although slightly lower levels, 15 to 20 ng/mL, may be sufficient for some infants and adults, higher levels, 40 to 60 ng/mL, may still be safe. This desirable range allows physicians to tailor treatment while taking season, lifestyle, vitamin D intake, and other sources of variation into account. We reserve 25OHD measurements for at-risk patients, defined by disease or lifestyle, and the use of 25OHD assays calibrated against the recommended international standards. Most target groups reach desirable target levels by a daily intake of 400 to 600 IU for children and 800 IU for adults. A total daily allowance of vitamin D of up to 1000 IU in the pediatric age groups, and up to 2000 IU in adults, tailored to an individual patient risk profile, is probably safe over long durations. Additional data are needed to validate the proposed range and vitamin D doses, especially in children, pregnant women, and non-white populations.

25-Hydroxyvitamin D3 Levels, BsmI Polymorphism and Insulin Resistance in Brazilian Amazonian Children

Vitamin D is associated with a wide range of other functions beyond bone development. We evaluated the factors associated with 25-hydroxyvitamin D levels in 974 children aged ≤ 10 years and the impact of BsmI polymorphism of the vitamin D receptor (VDR) gene (rs1544410) on metabolic parameters in a subsample (n: 430) with a follow-up 2 years later from the initial population-based cross-sectional study. Multiple linear regression models were used in the analyses. The prevalence (95% CI) of vitamin D deficiency, insufficiency and sufficiency of children was 11.1% (9.2-13.2), 21.8% (19.2-24.5) and 67.2% (64.1-70.1), respectively. Overall, 23% of the variation in serum 25-hydroxyvitamin D concentrations was accounted for by BsmI polymorphism β = -0.053 (95% CI) (-0.100, -0.006), maternal schooling (≥ 9 years) β = 0.100 (0.039, 0.161), serum vitamin E β = 0.478 (0.381, 0.574), total cholesterol concentration β = 0.232 (0.072, 0.393) and serum folate β = 0.064 (0.013, 0.115). BsmI polymorphism was positively associated with HOMA-IR β = 0.122 (0.002, 0.243) and fasting glucose concentration β = 1.696 (0.259, 3.133). In conclusion, variables related to socioeconomic level, the presence of the allele risk for BsmI and other nutrient concentrations were associated with serum 25-hydroxyvitamin D concentrations. Our results suggest that BsmI polymorphism is correlated with metabolic outcomes.

Normal bone mass and normocalcemia in adulthood despite homozygous vitamin D receptor mutations

Adding to the debate around vitamin D's effects on skeletal health, we report the long-term follow-up of two patients with severe vitamin D receptor mutations, who had normal bone mass acquisition and normalization of calcemia around puberty, suggesting that vitamin D might not be essential for skeletal health in adulthood.

INTRODUCTION

Vitamin D plays a pivotal role in calcium homeostasis, and the consequences of vitamin D insufficiency for skeletal health, as well as the importance of its supplementation, are a matter of great interest. Individuals bearing homozygous vitamin D receptor (VDR) defects present with severe hypocalcemic rickets in early infancy due to vitamin D resistance.

METHODS

Here, we report the follow-up of two patients with hereditary vitamin D-resistant rickets (HVDRR), focusing on bone mass acquisition and evolution of calcemia.

RESULTS

Patient 1 is a 30-year-old male bearing a homozygous p.Arg30* nonsense mutation in the VDR DNA-binding domain, who presented at 6 months. From 9 years of age, treatment requirement decreased progressively. Follow-up with DXA showed normal bone mass acquisition. In adulthood, he maintains normocalcemia without calcium supplementation and has no signs of bone fragility. Patient 2 is a 37-year-old female with milder HVDRR and alopecia due to a homozygous p.Gly319Val mutation in the VDR ligand-binding domain. Around puberty, hypercalciuria and kidney stones were detected, resulting in suspension of treatment. Follow-up with DXA revealed normal bone mass, and she maintained normocalcemia without supplementation during gestation and lactation.

CONCLUSIONS

The long-term follow-up of HVDRR provides insights into the role of vitamin D in human calcium homeostasis and bone health. The normalization of calcemia and normal bone mass acquisition despite a permanently dysfunctional VDR suggest that vitamin D might not be essential for skeletal health in adulthood. Extrapolation of these findings may have implications in broader clinical settings, especially considering widespread vitamin D supplementation.