Association between bone mass and fractures in children: a prospective cohort study

Sex differences in physical activity dose-response effects on site-specific bone mineral density during childhood and adolescence

Physical activity (PA) serves as a modifiable determinant of bone mineral density (BMD). However, sex- and site-specific dose-response relationships remain poorly defined. Leveraging data from the National Health and Nutrition Examination Survey (NHANES 2011-2014), this cross-sectional study investigated sex-specific associations between accelerometer-derived PA (volume and intensity) and site-specific BMD in 2,659 children and adolescents aged 8-19 years. BMD assessment was conducted via dual-energy X-ray absorptiometry, and PA was quantified using monitor-independent movement summary units (MIMS). Linear and nonlinear analyses revealed distinct patterns: boys exhibited stronger linear associations between PA volume and BMD at weight-bearing sites (e.g., pelvis, arms, and legs; β = 0.003-0.004, P < 0.05), and girls demonstrated nonlinear thresholds (e.g., volume threshold: 15.0 × 103 MIMS/day). Both sexes had intensity-driven thresholds (~ 45-49 MIMS/min), with diminishing returns above these values (β = 0.010 in boys; stagnation in girls). Directional trends suggest the greater BMD gains per standard deviation (SD) increase in PA for boys compared with that for girls across most skeletal regions (e.g., total body less head: 0.131 SD vs. 0.106 SD for intensity). However, statistical significance (P < 0.05) was observed only for arm BMD responses. Mechanistic analyses highlighted the corresponding biomechanical principles, with weight-bearing regions showing stronger PA-BMD links than nonweight-bearing sites (e.g., spine). These findings underscore the importance of prioritizing high-intensity, weight-bearing activities, particularly for girls, to optimize skeletal health during growth. Public health strategies should focus on achieving, rather than exceeding, the identified daily 60 min intensity thresholds (~ 45-49 MIMS/min) through school- and community-based interventions.

The gSOS Polygenic Score is Associated with Bone Density and Fracture Risk in Childhood

The polygenic risk score genetic quantitative ultrasound speed of sound (gSOS) was developed using machine learning algorithms in adults of European ancestry and associates with reduced odds of fracture in adults. We aimed to determine if gSOS was associated with bone health in children. Two observational studies of children were evaluated: (1) children enrolled in the Bone Mineral Density in Childhood Study (BMDCS) with genetic data (N=1,727); and (2) children with genetic data for research at the Children's Hospital of Philadelphia (CHOP; N=10,301). Genetic variants were used to calculate gSOS and genetic ancestry. For the BMDCS, puberty stage, dietary calcium, physical activity and fracture accumulation (none or ≥1 fracture) were self-reported, height and weight were measured and BMI calculated. Areal bone mineral density (aBMD) of the lumbar spine, hip, radius, and whole body were assessed by dual energy X-ray absorptiometry and expressed as Z-scores. The CHOP study paired genetic data with documentation of fracture in the electronic health record (EHR). gSOS associated with higher aBMD Z-scores across 7 skeletal sites [e.g., a 1 SD increase in gSOS associated with 0.17 (95% CI: 0.10-0.24) higher lumbar spine aBMD Z-score]. These associations were consistent for males and females, age, puberty stage, and lifestyle factors, and most consistent among children of European genetic ancestry. A 1 SD increase in gSOS associated with 12% and 16% reduced likelihood of self-reported fracture in the BMDCS (OR=0.84, 95% CI: 0.74, 0.95) and a recorded fracture in the CHOP EHR (OR=0.88; 95% CI: 0.82, 0.95). No sex or genetic ancestry differences were found. A higher gSOS score associated with higher aBMD at multiple skeletal sites and reduced odds of fracture in two independent pediatric samples. This genetic tool may have clinical utility to help enhance bone health in early life and protect against fracture across the lifespan.

Is there an association between birth characteristics and fractures in young adults? The HUNT Study, Norway

This population study investigated the association between birth characteristics and fracture risk in 11,099 young adults (aged 19-54 years). Our findings indicate that birth weight, gestational age, and birth weight for gestational age were not associated with fractures in the wrist, humerus, hip, and spine in this population.

PURPOSE

Skeletal development starts during fetal life, and it is estimated that most bone formation occurs in the 3rd trimester. This study examined the association between birth characteristics and fractures of the wrist, humerus, hip, and spine, in young adults (19-54 years).

METHODS

11.099 participants in the 3rd survey of the HUNT Study (2006-2008) were linked with the Medical Birth Registry of Norway and hospital records. Fractures of the wrist, humerus, hip, and spine were identified using ICD9/10 codes between 1988 and 2021. Follow-up was from date of participation in HUNT until a first fracture, emigration, death, or end of study. Cox regression was used to estimate hazard ratios (HR) of fracture associated with birth characteristics (95% CI), adjusted for birth year, sex, maternal age, and maternal morbidity. In a secondary analysis, follow-up started in 1988.

RESULTS

During a median follow-up of 14.0 years (153,657 person-years), 290 fractures occurred. Mean age at first fracture was 41.4 years (SD 7.4). Overall, there were no clear associations between birth characteristics and fractures in these data. HR for fracture was 0.43 (0.15-1.24) for those with a birth weight < 2.5 kg (reference birth weight 3.5 - 3.9 kg); 1.04 (0.74 - 1.46) for those born small for gestational age (< 10th percentile, reference 10 - 90th percentile); and 0.63 (0.33 - 1.23) for those born preterm (reference term births). The secondary analysis from 1988, including 539 fractures, gave similar results as the main analysis.

CONCLUSION

Birth weight, gestational age, or birth weight for gestational age was not associated with an increased risk of fractures of the wrist, humerus, hip, and spine in young adults.

Enhanced osteogenic potential of iPSC-derived mesenchymal progenitor cells following genome editing of GWAS variants in the RUNX1 gene

Recent genome-wide association studies (GWAS) identified 518 significant loci associated with bone mineral density (BMD), including variants at the RUNX1 locus (rs13046645, rs2834676, and rs2834694). However, their regulatory impact on RUNX1 expression and bone formation remained unclear. This study utilized human induced pluripotent stem cells (iPSCs) differentiated into osteoblasts to investigate these variants' regulatory roles. CRISPR/Cas9 was employed to generate mutant (Δ) iPSC lines lacking these loci at the RUNX1 locus. Deletion lines (Δ1 and Δ2) were created in iPSCs to assess the effects of removing regions containing these loci. Deletion lines exhibited enhanced osteogenic potential, with increased expression of osteogenic marker genes and Alizarin Red staining. Circularized chromosome conformation capture (4C-Seq) was utilized to analyze interactions between BMD-associated loci and the RUNX1 promoter during osteogenesis. Analysis revealed altered chromatin interactions with multiple gene promoters including RUNX1 isoform, as well as SETD4, a histone methyltransferase, indicating their regulatory influence. Interestingly, both deletion lines notably stimulated the expression of the long isoform of RUNX1, with more modest effects on the shorter isoform. Consistent upregulation of SETD4 and other predicted targets within the Δ2 deletion suggested its removal removed a regulatory hub constraining expression of multiple genes at this locus. In vivo experiments using a bone defect model in mice demonstrated increased bone regeneration with homozygous deletion of the Δ2 region. These findings indicate that BMD-associated variants within the RUNX1 locus regulate multiple effector genes involved in osteoblast commitment, providing valuable insights into genetic regulation of bone density and potential therapeutic targets.

Medical Management for Fracture Prevention in Children with Osteogenesis Imperfecta

There are no licensed treatments for children with osteogenesis imperfecta. Children currently receive off-label treatment with bisphosphonates, without any consistent approach to dose, drug or route of administration. Meta-analyses suggest that anti-fracture efficacy of such interventions is equivocal. New therapies are undergoing clinical trials, and it is likely that one or more will receive marketing authorisation within the next three to five years. The long-term outcome from such interventions will need to be studied carefully well beyond the period over which the clinical trials are conducted, and a consistent approach to the collection of data in this regard will be needed as a major collaborative effort.

Pregnancy vitamin D supplementation and offspring bone mineral density in childhood follow-up of a randomized controlled trial

BACKGROUND

Findings from the Maternal Vitamin D Osteoporosis Study (MAVIDOS) trial demonstrated a positive effect of gestational cholecalciferol supplementation on offspring bone mineral density (BMD) at age 4 y. Demonstrating the persistence of this effect is important to understanding whether maternal vitamin D supplementation could be a useful public health strategy to improving bone health.

OBJECTIVES

We investigated whether gestational vitamin D supplementation increases offspring BMD at ages 6-7 y in an exploratory post-hoc analysis of an existing trial.

METHODS

In the MAVIDOS randomized controlled trial, pregnant females <14 wk' gestation with a singleton pregnancy and serum 25-hydroxyvitamin D 25-100nmol/l at 3 United Kingdom hospitals (Southampton, Sheffield, and Oxford) were randomly assigned to either 1000 IU/d cholecalciferol or placebo from 14 to 17-wk gestation until delivery. Offspring born at term to participants recruited in Southampton were invited to the childhood follow-up at ages 4 and 6-7 y. The children had a dual-energy X-ray absorptiometry (DXA, Hologic discovery) scan of whole-body-less-head (WBLH) and lumbar spine, from which bone area, bone mineral content (BMC), BMD, and bone mineral apparent density (BMAD) were derived. Linear regression was used to compare the 2 groups adjusting for age, sex, height, weight, duration of consumption of human milk, and vitamin D use at 6-7 y.

RESULTS

A total of 454 children were followed up at ages 6-7 y, of whom 447 had a usable DXA scan. Gestational cholecalciferol supplementation resulted in higher WBLH BMC [0.15 SD, 95% confidence interval (CI): 0.04, 0.26], BMD (0.18 SD, 95% CI: 0.06, 0.31), BMAD (0.18 SD, 95% CI: 0.04, 0.32), and lean mass (0.09 SD, 95% CI: 0.00, 0.17) compared with placebo. The effect of pregnancy cholecalciferol on bone outcomes was similar at ages 4 and 6-7 y.

CONCLUSIONS

Supplementation with cholecalciferol 1000 IU/d during pregnancy resulted in greater offspring BMD and lean mass in mid-childhood compared with placebo in this exploratory post-hoc analysis. These findings suggest that pregnancy vitamin D supplementation may be an important population health strategy to improve bone health.

TRIAL REGISTRATION NUMBER

This trial was registered at the ISRCTN (https://doi.org/10.1186/ISRCTN82927713) as 82927713 and EUDRACT (https://www.clinicaltrialsregister.eu/ctr-search/trial/2007-001716-23/results) as 2007-001716-23.

Bone Accrual Trajectories in Children and Adolescents with Perinatal HIV Infection

CONTEXT

Low bone mineral density (BMD) has been reported in children and adolescents living with perinatally-acquired HIV (PHIV). Little is known about their bone accrual through puberty compared to an uninfected healthy cohort.

OBJECTIVE

To compare bone accrual in PHIV and healthy children.

DESIGN

PHIV children aged 7-16 years had dual energy X-ray absorptiometry (DXA) at entry, 2 years, and then at least 2 years later. Bone accrual was compared to healthy children from the Bone Mineral Density in Childhood Study (BMDCS).

SETTING

United States academic clinical research centers.

PATIENTS

172 PHIV; 1321 BMDCS.

ANALYSIS

We calculated height-adjusted whole-body and spine BMD and bone mineral content (BMC) Z-scores in PHIV using BMDCS reference curves. We fit piecewise weighted linear mixed effects models with change points at 11 and 15 years, adjusted for age, sex, race, height Z-score, and Tanner stage, to compare BMD and BMC Z-scores across actual age by cohort.Main Outcome Measure: BMD/BMC Z-scores.

RESULTS

Height-adjusted whole-body BMD and BMC Z-scores in PHIV were lower across age compared to BMDCS children. Spine BMD Z-score across age was higher in PHIV after height adjustment. Whole-body and spine bone area tended to be lower in PHIV. PHIV had slower accrual in whole-body and spine bone area before 14 years. After 15 years, bone area accruals were similar, as were height-adjusted spine BMC Z-scores, across age.

CONCLUSIONS

PHIV had persistent deficits in all measures except height-adjusted spine BMD and BMC Z-scores. Data are needed on PHIV followed to adulthood.

Initial results from the PHEFREE longitudinal natural history study: Cross-sectional observations in a cohort of individuals with phenylalanine hydroxylase (PAH) deficiency

Over fifty years have passed since the last large scale longitudinal study of individuals with PAH deficiency in the U.S. Since then, there have been significant changes in terms of treatment recommendations as well as treatment options. The Phenylalanine Families and Researchers Exploring Evidence (PHEFREE) Consortium was recently established to collect a more up-to-date and extensive longitudinal natural history in individuals with phenylketonuria across the lifespan. In the present paper, we describe the structure and methods of the PHEFREE longitudinal study protocol and report cross-sectional data from an initial sample of 73 individuals (5 months to 54 years of age) with PAH deficiency who have enrolled. Looking forward, the study holds the promise for advancing the field on several fronts including the validation of novel neurocognitive tools for assessment in individuals with PKU as well as evaluation of the long-term effects of changes in metabolic control (e.g., effects of Phe-lowering therapies) on outcome.

Cohort profile of an early life observational cohort in China: Bone and MicroBiOme onset (BAMBOO) study

PURPOSE

The Bone And MicroBiOme Onset (BAMBOO) study is an ongoing prospective observational cohort study conducted in Tianjin, China, aiming to determine age-appropriate trajectories for microbiome maturation and bone development and to identify the influence of dietary factors in the process.

PARTICIPANTS

The recruitment started in September 2021 and was completed in February 2023. A total of 1380 subjects were recruited, 690 at birth (group 1) and 690 at 6 months of age (group 2). Groups 1 and 2 will be followed up for 12 months and 36 months, respectively.

FINDINGS TO DATE

The age of the mothers was 31.1±3.7 (mean±SD), and the birth weight of infants was 3.3±0.5 kg with an incidence of caesarean section 50.4%. Food diary information of the first 100 subjects showed that 64 food items were introduced by 6 months. A pilot microbiome analysis revealed that at the species level, bacterial communities were composed of mostly Bacteroides dorei, Bacteroides vulgatus and Escherichia coli, which were consistent with that of previous reports. Feasibility assessments of breast milk vitamin D and human milk oligosaccharides were validated through certified reference measurements. The early data assessment showed a high reliability of the data generated from this study.

FUTURE PLANS

Data collection will be completed in August 2025. Four stage-statistical analyses will be performed as the cohort reaches certain age thresholds before the final report. Analysis of BAMBOO data will be used to develop age-appropriate trajectories for microbiome maturation and bone development for children aged 0-3 years and investigate the contribution of dietary factors in the process.

TRIAL REGISTRATION NUMBER

ChiCTR2100049972.

A Comprehensive Review of Bone Health in a Child: From Birth to Adulthood

Bone health is critical for growth and development during childhood. Although fractures are common in children, fractures occurring in the absence of trauma should prompt physicians to consider underlying bone health disorders. This article provides an overview of the current definition of osteoporosis in children, highlighting its limitations and the potential for underdiagnosis. It also discusses the timing of screening initiation and various techniques used to assess bone health, along with their respective benefits and limitations. In addition, this article identifies several causes of primary and secondary osteoporosis in children, shedding light on previously overlooked disorders that can contribute to poor bone quality. The article emphasizes the importance of a multidisciplinary approach to therapeutic management and aims to optimize patient outcomes and improve the overall care of pediatric bone health disorders.

Exposure to perfluoroalkyl substances and longitudinal changes in bone mineral density in adolescents and young adults: A multi-cohort study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may impair bone development in adolescence, which impacts life-long bone health. No previous studies have examined prospective associations of individual PFAS and their mixture with bone mineral density (BMD) changes in Hispanic young persons, a population at high risk of osteoporosis in adulthood.

OBJECTIVES

To examine associations of individual PFAS and PFAS mixtures with longitudinal changes in BMD in an adolescent Hispanic cohort and examine generalizability of findings in a mixed-ethnicity young adult cohort (58.4% Hispanic).

METHODS

Overweight/obese adolescents from the Study of Latino Adolescents at Risk of Type 2 Diabetes (SOLAR; n = 304; mean follow-up = 1.4 years) and young adults from the Southern California Children's Health Study (CHS; n = 137; mean follow-up = 4.1 years) were included in this study. Plasma PFAS were measured at baseline and dual x-ray absorptiometry scans were performed at baseline and follow-up to measure BMD. We estimated longitudinal associations between BMD and five PFAS via separate covariate-adjusted linear mixed effects models, and between BMD and the PFAS mixture via quantile g-computation.

RESULTS

In SOLAR adolescents, baseline plasma perfluorooctanesulfonic acid (PFOS) was associated with longitudinal changes in BMD. Each doubling of PFOS was associated with an average -0.003 g/cm2 difference in change in trunk BMD per year over follow-up (95% CI: -0.005, -0.0002). Associations with PFOS persisted in CHS young adults, where each doubling of plasma PFOS was associated with an average -0.032 g/cm2 difference in total BMD at baseline (95% CI -0.062, -0.003), though longitudinal associations were non-significant. We did not find associations of other PFAS with BMD; associations of the PFAS mixture with BMD outcomes were primarily negative though non-significant.

DISCUSSION

PFOS exposure was associated with lower BMD in adolescence and young adulthood, important periods for bone development, which may have implications on future bone health and risk of osteoporosis in adulthood.

Fracture Risk in Patients with Anorexia Nervosa Over a 40-Year Period

Researchers have reported increased fracture risk in patients with anorexia nervosa (AN), but more knowledge on the long-term risk and the effects of age, male sex, and time-related changes is still needed. We examined the long-term (up to 40 years) fracture risk among patients with AN compared to a matched comparison cohort from the general population. We utilized data from the Danish Health Care Registers to identify 14,414 patients with AN (13,474 females and 940 males) diagnosed between 1977 and 2018, with a median age of 18.6 years and median follow-up time of 9.65 years. We calculated adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) using Cox regression analysis for overall and site-specific fracture risks. The overall aHR of any fracture was 1.46 [95% CI: 1.36 to 1.48], with an aHR of 1.50 [95% CI: 1.43 to 1.57] for females and 0.95 [95% CI: 0.82 to 1.1] for males. For specific fractures we found an association with femur fractures both in females 4.06 [95% CI: 3.39 to 4.46] and in males 2.79 [95% CI: 1.45 to 2.37] and for fractures of the spine (females 2.38 [95% CI: 2.00 to 2.84], males 2.31 [95% CI: 1.20 to 4.42]). The aHR of any fracture decreased from 1.66 [95% CI: 1.52 to 1.81] in the period from 1977 to 1997 to 1.40 [95% CI: 1.33 to 1.40] from 1998 to 2018. In conclusion, we found that AN was associated with a 46% increased risk of any fracture up to 40 years after diagnosis. We found no overall increased risk in males, but in both sexes we found a particularly high site-specific fracture risk in the spine and femur. Fracture risk decreased in recent decades, indicating that more patients with AN have been diagnosed with presumably less severe disease and that the earlier detection and intervention of AN in recent years may translate into a lower facture risk. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Decreased bone mass in adolescents with bone fragility fracture but not in young children: a case-control study

Background

The incidence of distal forearm fracture due to minimal/moderate trauma shows a bimodal distribution for age at event, with one peak occurring during early adolescence, in both boys and girls and the other one in postmenopausal females. The aim of this study was, therefore, to document whether the relationship between bone mineral density and fracture is different in young children compared with adolescents.

Methods

A matched-pair, case-control study has been conducted to evaluate bone mineral density in 469 young children and 387 adolescents of both sexes, with/without fracture due to minimal/moderate trauma with assurance that the compared groups were equally susceptible to the outcome event. All fractures were radiographically confirmed. The study utilized bone mineral areal density of the total body, spine, hips, and forearm; volumetric bone mineral density of the forearm; and metacarpal radiogrammetry measurements. The study controlled for skeletal development, bone geometry, body composition, hand grip strength, calcium intake, and vitamin D status.

Results

Adolescents with distal forearm fracture have reduced bone mineral density at multiple skeletal regions of interest. This was documented by the bone mineral areal density measurements at multiple skeletal sites (p < 0.001), volumetric bone mineral density measurements of the forearm (p < 0.0001), and metacarpal radiogrammetry (p < 0.001). Adolescent females with fracture had reduced cross-sectional areas of the radius and metacarpals. The bone status of young female and male children with fracture was no different to its controls. Increased body fatness was more prevalent among fracture cases than in controls. Around 72% of young female and male children with fracture had serum 25-hydroxyvitamin D levels below the threshold of 31 ng/ml, compared with only 42% of female controls and to 51% of male controls.

Conclusions

Adolescents with bone fragility fracture had reduced bone mineral density at multiple skeletal regions of interest, whereas this was not the case with younger children. The results of the study may have implications for the prevention of bone fragility in this segment of the pediatric population.

Epidemiological Investigation of Pediatric Fractures-A Retrospective Cohort Study of 1129 Patients

Background and Objectives: Fractures are common in pediatric trauma, and they are caused by a broad spectrum of factors. Only a few studies have discussed the mechanisms of injury and their relationships to different types of fractures. The most frequent type of fractures in different age groups remains unclear. Therefore, we aim to summarize the epidemiological characteristics of pediatric fractures in a medical center in Zhuhai, China from 2006 to 2021 and analyze the causes of fractures with the highest frequency in different age groups. Materials and Methods: We extracted the information from the Zhuhai Center for Maternal and Child Health Care of those under 14 years old who had fractures from 2006 to 2021. Results: We reviewed the information of 1145 children. The number of patients increased during the 15 years (p < 0.0001). The number of patients was significantly different between genders after Y2 (p = 0.014). In addition, more than two-thirds of patients (71.3%) had upper limb fractures, and all types of falls were the most common cause of fractures (83.6%). The incidence demonstrated an insignificant difference in age groups except for the fractures of humerus and radius. Moreover, we discovered that the prevalence of fall-related injuries decreased with age, while that of sports-related injuries increased with age. Conclusions: Our study demonstrates that the prevalence of fall-related injuries decreases with age, and that of sports-related injuries increases with age. Most patients have upper limb fractures, and all types of falls are the most common cause of fractures. Fracture types with the highest frequency differ in each age group. These findings might supplement current epidemiological knowledge of childhood fracture and provide references for decision-making in children's health policies.

Fracture prevalence and its association with bone density among children living with HIV in Zimbabwe

OBJECTIVES

HIV infection impairs bone density in children living with HIV (CLWH). We aimed to determine the prevalence of self-reported fracture (past or current), associated risk factors and disability, by HIV status in Zimbabwean children.

DESIGN

Cross-sectional study.

METHODS

We recruited CLWH aged 8-16 years taking antiretroviral therapy (ART) for ≥2 years from HIV clinics, and HIV-uninfected children from schools in Harare. Interviewer-administered questionnaires collected data on fracture site and management, sociodemographics, dietary calcium and vitamin D, physical activity and HIV history. Dual-energy X-ray absorptiometry (DXA) measured size-adjusted bone density.

RESULTS

We recruited 303 CLWH [mean (SD) age 12.5 (2.5) years; 50% female] and 306 children without HIV [12.5 (2.5) years; 51% female]. Median age at HIV diagnosis in CLWH was 3.0 years [interquartile range (IQR) 1.2, 5.9], and median ART duration 8.1 years [IQR 6.2, 9.5]. 53.8% CLWH had self-reported disability and/or functional impairment, vs. 29.4% children without HIV. Fracture prevalence was 5.9% with no difference by HIV status [21/306 (6.9%) vs. 14/303 (4.6%), P  = 0.24]. Male sex was associated with fractures. Low size-adjusted bone density ( Z -score < -2) was associated with prevalent fractures in CLWH {risk ratio [RR] 1.14 (95% confidence interval (CI) -0.02, 2.29]}, but not in children without HIV [RR -0.04 (-2.00, 1.91)], P -interaction = 0.27. All sought medical attention for their fracture(s), but CLWH were less often admitted to hospital [2/14 (14.3%) vs. 7/21 (33.3%)].

CONCLUSION

Prevalent fractures may be associated with low lumbar spine bone density in CLWH. Fracture surveillance and strategies to reduce future fracture risk are warranted as CLWH enter adulthood.

Aging and Bone Metabolism

Changes in bone architecture and metabolism with aging increase the likelihood of osteoporosis and fracture. Age-onset osteoporosis is multifactorial, with contributory extrinsic and intrinsic factors including certain medical problems, specific prescription drugs, estrogen loss, secondary hyperparathyroidism, microenvironmental and cellular alterations in bone tissue, and mechanical unloading or immobilization. At the histological level, there are changes in trabecular and cortical bone as well as marrow cellularity, lineage switching of mesenchymal stem cells to an adipogenic fate, inadequate transduction of signals during skeletal loading, and predisposition toward senescent cell accumulation with production of a senescence-associated secretory phenotype. Cumulatively, these changes result in bone remodeling abnormalities that over time cause net bone loss typically seen in older adults. Age-related osteoporosis is a geriatric syndrome due to the multiple etiologies that converge upon the skeleton to produce the ultimate phenotypic changes that manifest as bone fragility. Bone tissue is dynamic but with tendencies toward poor osteoblastic bone formation and relative osteoclastic bone resorption with aging. Interactions with other aging physiologic systems, such as muscle, may also confer detrimental effects on the aging skeleton. Conversely, individuals who maintain their BMD experience a lower risk of fractures, disability, and mortality, suggesting that this phenotype may be a marker of successful aging. © 2023 American Physiological Society. Compr Physiol 13:4355-4386, 2023.

Early life organophosphate ester exposures and bone health at age 12 years: The Health Outcomes and Measures of the Environment (HOME) Study

BACKGROUND

No human studies have evaluated early life organophosphate ester (OPE) exposures with bone health outcomes, despite evidence of osteotoxicity.

OBJECTIVES

We assessed associations of urinary OPE metabolites measured across early life with areal bone mineral density (aBMD) and bone mineral content (BMC) at age 12 years.

METHODS

Among 223 mother-child dyads enrolled in the Health Outcomes and Measures of the Environment (HOME) Study, we quantified concentrations of bis-2-chloroethyl phosphate (BCEP), bis-(1,3-dichloro-2-propyl) (BDCIPP), di-n-butyl phosphate (DnBP), and diphenyl phosphate (DPHP) in urine collected from mothers during pregnancy and children at ages 1, 2, 3, 5, and 8 years. At age 12 years, we performed dual energy x-ray absorptiometry and calculated aBMD and BMC z-scores at six skeletal sites. We estimated overall and sex-stratified BMD/BMC z-score differences per interquartile range (IQR) increase in OPE concentrations at multiple exposure timepoints: gestation (average) and 1-3 (average), 5, and 8 years.

RESULTS

In adjusted models, overall associations of BCEP and BDCIPP with total hip and 1/3rd distal radius aBMD and BMC varied significantly by exposure timepoint, as did BDCIPP with whole body aBMD. For example, differences (95 % CI) in total hip aBMD z-score per IQR increase in BDCIPP were 0.33 (0.01, 0.64), -0.10 (-0.34, 0.14), -0.18 (-0.40, 0.05), and 0.14 (-0.09, 0.38) for concentrations during gestation and at 1-3, 5, and 8 years, respectively. Overall DnBP and DPHP associations were generally null at all timepoints. We observed sex-specific associations for some timepoints and skeletal sites. For example, an IQR increase in 8-year DPHP was associated with a 0.21 (0.05, 0.38) greater total hip aBMD z-score among females but -0.19 (-0.43, 0.05) lower z-score among males.

DISCUSSION

Early life OPE exposures may be associated with sex- and exposure period-dependent alterations in early adolescent bone mineral accrual and strength.

Use of Dual-Energy X-ray Absorptiometry in Children with Inflammatory Bowel Disease: A Large Single Centre Study

PURPOSE

Low bone mineral density (BMD) is a complication in children with inflammatory bowel disease (IBD). There are limited data evaluating dual-energy x-ray absorptiometry (DXA) as a screening tool for low BMD in children with IBD. We performed a single site retrospective analysis of DXA use.

METHODS

Children aged 5-18 years with IBD diagnosed between 2013 to 2017 at the Royal Children's Hospital, Australia, were included. Patient demographics, measures of disease activity, DXA scores, and factors related to BMD were collected.

RESULTS

Over a median follow up of 5.1 (4-6.4) years, 72/239 (30.1%) children underwent DXA, and 28/239 (11.7%) children had a second DXA. Our DXA practice differed to consensus guidelines regarding initial screening based on height and/or body mass index (BMI) z-score (8/17 [47.1%]), and repeat surveillance (13/42 [31.0%]). Children had a median lumbar spine (LS) z-score -0.80 (-1.65-0.075). Children with LS z-score≤-2.0 (n=14) had lower weight (6.57 [1.78-23.7] vs. 51.1 [26.5-68.7], p=0.0002) and height centiles (3.62 [1.17-17.1] vs. 42 [16.9-67.1], p=0.0001), and higher faecal calprotectin (FCP) (3041 [1182-4192] vs. 585 [139-2419], p=0.009) compared to children with LS z-score>-2.0. No fractures were reported. Of 28 children who underwent a second DXA 1.6 (1.1-2.2) years following initial DXA, no significant change in z-scores occurred.

CONCLUSION

Children with IBD had low BMD. In addition to height centile and weight centile, FCP was associated with lower BMD, and should be considered in DXA screening guidelines. Greater clinician awareness of DXA consensus guidelines is required. Future prospective studies are required.

Bone deficits in children and youth with type 1 diabetes: A systematic review and meta-analysis

Deficits in bone mineral and weaker bone structure in children with type 1 diabetes (T1D) may contribute to a lifelong risk of fracture. However, there is no meta-analysis comparing bone properties beyond density between children with T1D and typically developing children (TDC). This meta-analysis aimed to assess differences and related factors in bone mineral content (BMC), density, area, micro-architecture and estimated strength between children with T1D and TDC. We systematically searched MEDLINE, Embase, CINAHL, Web of Science, Scopus, Cochrane Library databases, and included 36 in the meta-analysis (2222 children and youth with T1D, 2316 TDC; mean age ≤18 yrs., range 1-24). We estimated standardized mean differences (SMD) using random-effects models and explored the role of age, body size, sex ratio, disease duration, hemoglobin A1c in relation to BMC and areal density (aBMD) SMD using meta-regressions. Children and youth with T1D had lower total body BMC (SMD: -0.21, 95% CI: -0.37 to -0.05), aBMD (-0.30, -0.50 to -0.11); lumbar spine BMC (-0.17, -0.28 to -0.06), aBMD (-0.20, -0.32 to -0.08), bone mineral apparent density (-0.30, -0.48 to -0.13); femoral neck aBMD (-0.21, -0.33 to -0.09); distal radius and tibia trabecular density (-0.38, -0.64 to -0.12 and -0.35, -0.51 to -0.18, respectively) and bone volume fraction (-0.33, -0.56 to -0.09 and -0.37, -0.60 to -0.14, respectively); distal tibia trabecular thickness (-0.41, -0.67 to -0.16); and tibia shaft cortical content (-0.33, -0.56 to -0.10). Advanced age was associated with larger SMD in total body BMC (-0.13, -0.21 to -0.04) and aBMD (-0.09; -0.17 to -0.01) and longer disease duration with larger SMD in total body aBMD (-0.14; -0.24 to -0.04). Children and youth with T1D have lower BMC, aBMD and deficits in trabecular density and micro-architecture. Deficits in BMC and aBMD appeared to increase with age and disease duration. Bone deficits may contribute to fracture risk and require attention in diabetes research and care. STUDY REGISTRATION: PROSPERO (CRD42020200819).

Adiposity, Insulin Resistance, Cardiorespiratory Fitness, and Bone Health in Hispanic Children

CONTEXT

Childhood obesity disproportionately affects Hispanic youth. The skeletal system appears to be a target organ of the adverse effects of obesity. Yet, the relationship between adiposity and bone health in youth and the modulating factors are not well understood.

OBJECTIVE

This work aims to examine the relationship between adiposity, insulin resistance (IR), cardiorespiratory fitness (CRF), and bone mass in Hispanic youth.

METHODS

A total of 951 Hispanic youth (50% male), aged 4 to 19 years, participated in this cross-sectional design study from the Viva La Familia Study at Children's Nutrition Research Center. Bone mineral content (BMC) and density (BMD), lean mass (LM), total body fat mass (FM), truncal FM were obtained using dual-energy x-ray absorptiometry. Fasting glucose and insulin were obtained and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. CRF was measured using a treadmill ramp protocol. We applied linear regression models and mediation analyses.

RESULTS

Adiposity measures were negatively related to BMC and BMD after accounting for LM and sex. IR negatively contributed whereas CRF positively contributed to the variance in BMC and BMD, more notably in the pubertal age group. In mediation analysis, HOMA-IR partially mediated the negative relationship of adiposity to BMC (standardized indirect effect [IE] = -0.0382; 95% CI, -0.0515 to -0.0264) whereas the sequential IE of HOMA-IR and CRF partially attenuated (IE = -0.0026; 95% CI, -0.0053 to -0.0005) this relationship. Similar findings were seen with BMD as the primary outcome.

CONCLUSION

IR mediates the negative relationship between adiposity and bone mass whereas CRF may partially attenuate it.

Impact of Type 1 Diabetes Mellitus on Bone Health in Children

This paper gives an overview of the impact of type 1 diabetes on bone health in children and adolescents. Firstly, we analyse studies using dual X-ray absorptiometry to assess bone mineral content and bone mineral density. Then, we discuss modern, non-invasive techniques including peripheral quantitative computer tomography (pQCT) and high-resolution pQCT for the detailed assessment of bone health aspects including bone mass, bone geometry, bone microarchitecture, and bone strength. Thereafter, we explore some of the mechanisms that are responsible for diabetic bone disease in children, like low bone turnover and high sclerostin levels. Finally, we summarize some of the evidence for the importance of microvascular disease in the pathophysiology of diabetic bone disease.

Vitamin D: Before, during and after Pregnancy: Effect on Neonates and Children

A worldwide high prevalence of vitamin D (VD) deficiency has become of growing concern because of potential adverse effects on human health, including pregnant women and their offsprings. Beyond its classical function as a regulator of calcium and phosphate metabolism, together with its fundamental role in bone health in every stage of life, its deficiency has been associated to multiple adverse health effects. The classic effects of VD deficiency in pregnancy and neonates have been late hypocalcemia and nutritional rickets. Nevertheless, recent studies have linked VD to fertility and 25(OH)D with several clinical conditions in pregnancy: preeclampsia, gestational diabetes, higher incidence of cesarean section and preterm birth, while in infants, the clinical conditions are low birth weight, lower bone mass and possible relationship with the development of such diseases as bronchiolitis, asthma, type 1 diabetes, multiple sclerosis and autism included as VD non-classical actions. The supplementation with Vitamin D and achievement of optimal levels reduce maternal-fetal and newborn complications. Supplementation in children with VD deficiency reduces the risk of respiratory infections and possibly autoimmune diseases and autism. This review emphasizes the roles of Vitamin D deficiency and the consequences of intervention from preconception to infancy.

Vitamin D level, body mass index and fracture risk in children: vitamin D deficiency and fracture risk

The objective of this study was to determine the impacts of preventable causes of fracture, such as vitamin D deficiency, disturbed calcium homeostasis and obesity on fracture occurrence in minor traumas. In this way, the effects of relevant parameters on fracture may be further elucidated. A prospective case-control study in children aged 2-18 years children with and without fractures was performed. Participants with a pediatric trauma score higher than 10 presenting to minor trauma were included to exclude the significant impact of severe trauma on fracture. The effects of obesity, parameters associated with vitamin D and Ca homeostasis on fracture occurrence were evaluated. Univariate and multivariate analyses were used to test for associations between fracture status and the assessed variables. The relationships between the variables and the odds of fracture occurrence were examined using logistic regression models. The sample consisted of 76 patients and 50 controls. There were no significant differences between the patients and controls in terms of age, sex, trauma type and pubertal period. The patients had a significantly higher mean BMI percentile (61.2 ± 30.7, 36.7 ± 30.7; P < 0.001). Likewise, patients were more likely than controls to have a lower mean 25(OH)D level and mean phosphorus level (respectively, 13.4 ± 7.0, 17.3 ± 7.8; P = 0.004, and 4.6 ± 0.7, 5.1 ± 0.8; P < 0.001). Moreover, fractures were substantially more frequent in children with vitamin D deficiency (<20 ng/mL, χ2: 7.781, df: 1, P = 0.005). In the multivariate logistic model, BMI percentile and vitamin D levels remained significantly associated with increased odds of fracture [1.02 (1.01-1.04), P < 0.001 and 0.93 (0.89-0.98), P = 0.01]. The present study supports an association of high BMI and vitamin D deficiency with an increased odds of fracture occurrence in children. The findings may help physicians to reduce the risk factors of fracture by preventive efforts. Thus, unexpected health costs and morbidity may be minimized.

Glycomacropeptide in PKU-Does It Live Up to Its Potential?

The use of casein glycomacropeptide (CGMP) as a protein substitute in phenylketonuria (PKU) has grown in popularity. CGMP is derived from κ casein and is a sialic-rich glycophosphopeptide, formed by the action of chymosin during the production of cheese. It comprises 20–25% of total protein in whey products and has key biomodulatory properties. In PKU, the amino acid sequence of CGMP has been adapted by adding the amino acids histidine, leucine, methionine, tyrosine and tryptophan naturally low in CGMP. The use of CGMP compared to mono amino acids (L-AAs) as a protein substitute in the treatment of PKU promises several potential clinical benefits, although any advantage is supported only by evidence from non-PKU conditions or PKU animal models. This review examines if there is sufficient evidence to support the bioactive properties of CGMP leading to physiological benefits when compared to L-AAs in PKU, with a focus on blood phenylalanine control and stability, body composition, growth, bone density, breath odour and palatability.

Associations of pregnancy phthalate concentrations and their mixture with early adolescent bone mineral content and density: The Health Outcomes and Measures of the Environment (HOME) study

BACKGROUND

The developing fetus may be particularly susceptibility to environmental osteotoxicants, but studies of pregnancy phthalate exposures and childhood bone health are scarce.

OBJECTIVES

To examine relations of pregnancy phthalate exposure biomarkers with early adolescent bone mineral density (BMD) and bone mineral content (BMC) in a prospective birth cohort.

METHODS

We used data from 223 pregnant mothers and their children enrolled in a Cincinnati, OH area cohort from 2003 to 2006. We quantified monoethyl phthalate (MEP), monoisobutyl phthalate, monobutyl phthalate, monobenzyl phthalate, mono-(3-carboxypropyl) phthalate (MCPP), and four metabolites of di-2-ethylhexyl phthalate in maternal urine collected at 16 and 26 weeks gestation, and calculated the average of creatinine-standardized concentrations. Using dual x-ray absorptiometry measures at age 12 years, we calculated BMD and BMC Z-scores for six skeletal sites. In overall and sex-stratified models, we estimated covariate-adjusted associations per 2-fold increase in phthalate biomarker concentrations using linear regression, and estimated joint effects of the phthalate biomarkers mixture using Bayesian kernel machine regression (BKMR) and quantile g-computation.

RESULTS

In single phthalate models, several biomarkers were positively associated with BMC and BMD. For example, each doubling of MEP and MCPP, 1/3rd distal radius BMD Z-score increased by 0.09 (95% CI: 0.01, 0.17) and 0.16 (95% CI: 0.01, 0.31), respectively. For phthalate mixtures, associations were generally U-shaped among males and positive-linear among females, using both statistical methods. Mixture associations were strongest with forearm sites: in BKMR models, increasing all biomarkers from the 50th to 90th percentile was associated with a 0.64 (95% CI: 0.01, 1.28) greater 1/3rd distal radius BMD Z-score in males, and a 0.49 (95% CI: -0.13, 1.10) greater ultradistal radius BMD Z-score in females.

DISCUSSION

In this study, phthalate exposures during gestation were associated with increased BMD Z-scores in early adolescence, though further research is needed to determine implications for long-term skeletal health.

Physical Activity at Growth Induces Bone Mass Benefits Into Adulthood – A Fifteen‐Year Prospective Controlled Study

Daily school physical activity (PA) improves musculoskeletal traits. Whether or not benefits remain in adulthood is debated. We included in this study 131 children that took part in an intervention with 40 minutes of PA per school day (200 minutes per week) from age 6 to 9 years (grade one) to age 14 to 16 years (grade nine), whereas 78 children continued with national recommended school physical education of 60 minutes per week. Measurements were done with dual‐energy X‐ray absorptiometry (bone mineral content [BMC], bone mineral density [BMD], and bone area), and a computerized knee dynamometer (peak torque muscle strength) at study start, at the end of the intervention, and 7 years after the intervention. Group differences from study start and end of the intervention to 7 years thereafter were estimated by analyses of covariance (adjusted for sex and follow‐up time). Musculoskeletal gains from study start to 7 years after termination of the intervention were higher in the intervention group (total body less head BMC +182.5 g [95% confidence interval {CI}, 55.1–309.9] and BMD +0.03 g/cm² [95% CI, 0.003–0.05], femoral neck area + 0.2 cm² [95% CI, 0.1–0.4], and knee flexion peak torque muscle strength at 60 degrees per second +9.2 Nm [95% CI, 2.9–15.5]). There was no attenuation during the 7 years that followed termination of the intervention (all group comparisons p > 0.05). Benefits in musculoskeletal gains remain 7 years after termination of a daily school‐based PA program, without attenuation after termination of the program. Daily school PA may counteract low bone mass and inferior muscle strength in adulthood. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Downturn in Childhood Bone Mass: A Cross‐Sectional Study Over Four Decades

Screen time and physical inactivity have increased among children. As physical activity is a determinant of bone mass, there is a concern that children today have lower bone mass than earlier. If this is true, fractures may become more common in the future. In 2017–2018, we used single‐photon absorptiometry (SPA) to measure distal forearm bone mineral density (BMD; mg/cm²) in a normative cohort of 238 boys and 204 girls aged 7 to 15 years. We compared these results to BMD in a normative cohort collected in 1979–1981 (55 boys and 61 girls aged 7 to 15 years) measured by the same scanner. To investigate difference between the two cohorts, we used multiple linear regression with age, sex, and cohort as predictors. Predicted bone density at age 16 years was estimated through the slope values. The bone density‐age slope was flatter in the cohort measured in 2017–2018 than in the cohort measured 1979–1981 (−5.6 mg/cm²/yr [95% confidence interval −9.6 to −1.5]). Predicted bone density was at age 16 years in 2017–2018 in boys was 10% lower (−0.9 SD) and in girls 11% lower (−1.1 SD) than in their counterparts measured in 1979–1981. We found indications that children nowadays develop lower bone mass than four decades ago, giving concern that they may have a higher risk of osteoporosis and fragility fractures as they grow old. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Role of Polyphenols in the Metabolism of the Skeletal System in Humans and Animals – A Review

Polyphenols are a group of compounds arousing enormous interest due to their multiple effects on both human and animal health and omnipresence in plants. A number of in vitro and animal model studies have shown that all polyphenols exhibit anti-inflammatory and antioxidant activities, and play a significant role against oxidative stress-related pathologies. They also exert gut promotory effects and prevent chronic degenerative diseases. However, less attention has been paid to the potential influence of polyphenols on bone properties and metabolism. It is well known that proper growth and functioning of the organism depend largely on bone growth and health. Therefore, understanding the action of substances (including polyphenols) that may improve the health and functioning of the skeletal system and bone metabolism is extremely important for the health of the present and future generations of both humans and farm animals. This review provides a comprehensive summary of literature related to causes of bone loss during ageing of the organism (in both humans and animals) and possible effects of dietary polyphenols preventing bone loss and diseases. In particular, the underlying cellular and molecular mechanisms that can modulate skeletal homeostasis and influence the bone modeling and remodeling processes are presented.

Bone health in glucocorticoid-treated childhood acute lymphoblastic leukemia

Glucocorticoids (GCs) are widely used in the treatment of childhood acute lymphoblastic leukemia (ALL), but their long-term use is also associated with bone-related morbidities. Among others, growth deficit, decreased bone mineral density (BMD) and increased fracture rate are well-documented and severely impact quality of life. Unfortunately, no efficient treatment for the management of bone health impairment in patients and survivors is currently available. The overall goal of this review is to discuss the existing data on how GCs impair bone health in pediatric ALL and attempts made to minimize these side effects.

Musculoskeletal Benefits from a Physical Activity Program in Primary School are Retained 4 Years after the Program is Terminated

Daily school physical activity (PA) improves musculoskeletal traits. This study evaluates whether the benefits remain 4 years after the intervention. We followed 45 boys and 36 girls who had had 40 min PA/school day during the nine compulsory school years and 21 boys and 22 girls who had had 60 min PA/school week (reference), with measurements at baseline and 4 years after the program terminated. Bone mineral content (BMC; g) and bone mineral density (BMD; g/cm²) were measured by dual-energy X-ray absorptiometry and knee flexion peak torque relative to total body weight (PT_flexTBW) at a speed of 180 degrees/second with a computerized dynamometer. Group differences are presented as mean differences (adjusted for sex and duration of follow-up period) with 95% confidence intervals. The total gain bone mass [mean difference in spine BMC +32.0 g (14.6, 49.4) and in arms BMD of +0.06 g/cm² (0.02, 0.09)] and gain in muscle strength [mean difference in PT_flex180TBW +12.1 (2.0, 22.2)] were greater in the intervention than in the control group. There are still 4 years after the intervention indications of benefits in both bone mass and muscle strength gain. Daily school PA may counteract low bone mass and inferior muscle strength in adult life. ClinicalTrials.gov.NCT000633828 retrospectively registered 2008-11-03.

Associations of Maternal Serum Perfluoroalkyl Substances Concentrations with Early Adolescent Bone Mineral Content and Density: The Health Outcomes and Measures of the Environment (HOME) Study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may impair bone accrual and strength via endocrine disruption and nuclear receptor agonism, but human studies are primarily of adults or cross-sectional.

OBJECTIVES

We assessed associations of individual PFAS and their mixture during pregnancy with child bone mineral content (BMC) and areal bone mineral density (aBMD) at age 12 y.

METHODS

Among 206 mother-child pairs enrolled in a prospective cohort (2003-2006), we quantified perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS) in maternal serum collected during gestation or delivery. When children were age 12 y, we performed dual energy X-ray absorptiometry and calculated BMC, aBMD, and bone mineral apparent density (BMAD) z -scores for six skeletal sites. We estimated covariate-adjusted z -score differences per doubling of individual PFAS using linear regression and assessed the PFAS mixture using quantile g-computation and Bayesian kernel machine regression. We explored whether associations were modified by child's sex or mediated by whole-body lean mass.

RESULTS

In covariate-adjusted models, we found that higher maternal serum concentrations of PFOA, PFNA, and the PFAS mixture were associated with lower total hip and forearm (one-third distal radius) BMC z -scores in children. Differences in forearm BMC z -scores were - 0.17 [95% confidence interval (CI): - 0.35 , 0.01] and - 0.24 (95% CI: - 0.44 , - 0.05 ) per doubling of PFOA and PFNA, respectively, and - 0.18 (95% CI: - 0.34 , - 0.02 ) per quartile increase in the PFAS mixture. Child's sex modified PFOA associations for some skeletal sites; for example, differences in spine BMAD z -score per doubling were - 0.31 (95% CI: - 0.58 , - 0.03 ) among males and 0.07 (95% CI: - 0.16 , 0.30) among females (modification p = 0.04 ). Except for PFNA among females, these associations were not mediated by whole-body lean mass.

DISCUSSION

Maternal PFAS concentrations during pregnancy may be associated with lower bone mineral accrual and strength in early adolescence. https://doi.org/10.1289/EHP9424.

Bone health in children and youth with ASD: a systematic review and meta-analysis

Higher risk of fracture reported in individuals with autism spectrum disorder (ASD) might be linked to poor bone health and development in childhood. This study aimed to systematically review studies comparing imaged bone outcomes between children with ASD and typically developing children (TDC) or reference data, and to perform a meta-analysis comparing commonly reported bone outcomes. We searched articles published since August 2020 from PubMed, Cochrane Library, Web of Science, EMBASE, and Scopus databases. We included studies comparing areal bone mineral density (aBMD) between children with ASD and TDC in the qualitative analysis (meta-analysis), and evaluated other imaged bone outcomes qualitatively. Seven publications were identified for the systematic review, and four studies were included in the meta-analysis. The meta-analysis indicated lower aBMD at the total body (standardized mean difference = - 0.77; 95% CI, - 1.26 to - 0.28), lumbar spine (- 0.69; - 1.00 to - 0.39), total hip (- 1.00; - 1.82 to - 0.17), and femoral neck (- 1.07; - 1.54 to - 0.60) in children with ASD compared to TDC. Based on our qualitative review, limited evidence suggested 13% lower bone mineral content at the total body and 10-20% lower cortical area, cortical and trabecular thickness, and bone strength at the distal radius and tibia in children with ASD. Children with ASD have lower aBMD at the total body, lumbar spine, and hip and femoral neck compared to TDC. Limited evidence also suggests deficits in bone mineral content, micro-architecture, and strength in children with ASD.

The independent and interactive associations of physical activity intensity and vitamin D status with bone mineral density in prepubertal children: the PANIC Study

It is unclear how physical activity intensity and vitamin D status are related to bone health in prepubertal children. We found positive associations between vitamin D status and moderate-to-vigorous physical activity with bone in boys and girls. This highlights the importance of lifestyle factors for skeletal health prepuberty.

INTRODUCTION

The sex-specific independent and interactive associations of physical activity (PA) intensity and serum 25-hydroxyvitamin D (25(OH)D) levels with areal bone mineral density (aBMD) were investigated in prepubertal children.

METHODS

The participants were 366 prepubertal Finnish children (190 boys, 176 girls) aged 6-8 years. Linear regression analysed the associations of sedentary time (ST), light PA (LPA), moderate PA (MPA), moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) measured by accelerometery, and serum 25(OH)D with total body less head (TBLH) and lower-limb aBMD, measured by dual-energy X-ray absorptiometry.

RESULTS

There was no interaction between PA intensity or serum 25(OH)D and sex with aBMD. MPA and MVPA were positively associated with TBLH and lower-limb aBMD (β = 0.11, 95% CI 0.02-0.20, p = 0.01). Serum 25(OH)D was positively associated with TBLH and lower-limb aBMD (β = 0.09, 95% CI 0.01-0.18, p = 0.03). There were no interactions between PA intensity and serum 25(OH)D with aBMD.

CONCLUSION

Vitamin D status, MPA and MVPA levels in active prepubertal children were positively associated with aBMD. The influence of MVPA is due to the MPA component, though our findings regarding the role of VPA should be interpreted with caution, as shorter accelerometer epochs are needed to more accurately assess VPA. This study adds evidence to the promotion of MPA and behaviours to encourage optimal vitamin D status in supporting skeletal health in childhood, though these need not be used in conjunction to be beneficial, and a sex-specific approach is not necessary in prepubertal children.

TRIAL REGISTRATION NUMBER

NCT01803776 . Date of registration: 4/03/2013.

A Three-Year Longitudinal Study Comparing Bone Mass, Density, and Geometry Measured by DXA, pQCT, and Bone Turnover Markers in Children with PKU Taking L-Amino Acid or Glycomacropeptide Protein Substitutes

In patients with phenylketonuria (PKU), treated by diet therapy only, evidence suggests that areal bone mineral density (BMDa) is within the normal clinical reference range but is below the population norm. Aims: To study longitudinal bone density, mass, and geometry over 36 months in children with PKU taking either amino acid (L-AA) or casein glycomacropeptide substitutes (CGMP-AA) as their main protein source. Methodology: A total of 48 subjects completed the study, 19 subjects in the L-AA group (median age 11.1, range 5–16 years) and 29 subjects in the CGMP-AA group (median age 8.3, range 5–16 years). The CGMP-AA was further divided into two groups, CGMP100 (median age 9.2, range 5–16 years) (n = 13), children taking CGMP-AA only and CGMP50 (median age 7.3, range 5–15 years) (n = 16), children taking a combination of CGMP-AA and L-AA. Dual X-ray absorptiometry (DXA) was measured at enrolment and 36 months, peripheral quantitative computer tomography (pQCT) at 36 months only, and serum blood and urine bone turnover markers (BTM) and blood bone biochemistry at enrolment, 6, 12, and 36 months. Results: No statistically significant differences were found between the three groups for DXA outcome parameters, i.e., BMDa (L2–L4 BMDa g/cm²), bone mineral apparent density (L2–L4 BMAD g/cm³) and total body less head BMDa (TBLH g/cm²). All blood biochemistry markers were within the reference ranges, and BTM showed active bone turnover with a trend for BTM to decrease with increasing age. Conclusions: Bone density was clinically normal, although the median z scores were below the population mean. BTM showed active bone turnover and blood biochemistry was within the reference ranges. There appeared to be no advantage to bone density, mass, or geometry from taking a macropeptide-based protein substitute as compared with L-AAs.

Gestational Folate and Offspring Bone Health; The Vitamin D in Pregnancy Study

Maternal nutritional intake, such as folate and folic acid supplementation, during pregnancy may affect offspring bone health during childhood. We aimed to determine the associations between maternal dietary and supplementary folate intake and offspring bone health measures, including fracture risk. Data were obtained from 160 of 475 mother-child pairs who had returned for the 11-year follow up of the Vitamin D in Pregnancy Study, an observational cohort study. Incident fractures were ascertained from radiological records and dual X-ray absorptiometry was used to measure bone mineral density and content at 11 years of age. Maternal dietary folate intake during pregnancy was determined by Food Frequency Questionnaire and folate supplementation was determined through self-report. Both measures were undertaken at recruitment (before 16 weeks gestation) and at 28-32 weeks' gestation. Multivariable linear regression models and Cox regression models were used to examine associations. Results are presented as per 1000 µg folate for dietary measures. There were significant associations between maternal folate supplementation in early pregnancy (< 16 weeks gestation) and offspring spine bone mineral content (BMC) (β = 1.53, 95% CI 0.21, 2.86), spine area (β = 1.10, 95% CI 0.37, 1.82) and total body less head area (β = 329.30, 95% CI 3.50, 55.20) at the 11-year follow-up. The association between spine BMC was attenuated after adjustment for bone size (β = 0.13 95% CI - 0.85, 1.10). There was no association between maternal folate supplementation at 28-32 weeks' or maternal dietary intake at either time point with any offspring bone outcome. These data suggest that folate supplementation in early pregnancy may be associated with offspring bone size, but not other bone measures.

The Combined Effects of Milk Intake and Physical Activity on Bone Mineral Density in Korean Adolescents

The purpose of this study was to examine the combined effects of milk intake and physical activity on bone mineral density in adolescents. This study was conducted using data from the 2009–2011 Korea National Health and Nutrition Examination Survey (KNHANES), which provided measurements of bone mineral density (BMD) in addition to basic health-related data. This study included 1061 adolescents aged 13 to 18 years (557 males and 504 females) whose data on milk intake and participation time in moderate to vigorous physical activity were available. BMD was measured by dual-energy X-ray absorptiometry (DXA). Milk intake was assessed using the 24-h recall method, and the levels of physical activity were examined using a questionnaire. The physical activity questions of 2009–2011 KNHANES were based on the Korean version of the International Physical Activity Questionnaire (IPAQ) short form. The subjects were classified into four groups according to milk intake and physical activity level: no milk intake + low-level physical activity group (M_noP_low), no milk intake + high-level physical activity group (M_noP_high), milk intake + low-level physical activity group (M_yesP_low), and milk intake + high-level physical activity group (M_yesP_high). The results of partial correlation controlling for age, body mass index (BMI), and energy intake showed that the BMD variables were associated significantly with physical activity in both males and females. Among males, the M_noP_low group had the lowest BMD in all BMD variables, showing a significant difference from the high-level physical activity groups (M_noP_high, M_yesP_high) by multiple logistic regression analysis. Among females, the M_yesP_high group showed a significantly higher lumbar BMD value than the other groups. The M_noP_low group had approximately 0.3 to 0.5 times lower odds ratio for median or higher BMD values, compared to M_yesP_high group. These results show that milk intake and physical activity have a combined effect on BMD, and suggest that to achieve healthy bone growth, it is important to encourage both moderate to vigorous physical activity and milk intake during adolescence.

Clinical Criteria Can Identify Children With Osteopenia in Newly Diagnosed Crohn Disease

OBJECTIVES

Chronic inflammation of Crohn disease (CD) is associated with reduced bone mineral density (BMD). As bone mass is almost exclusively accrued during childhood, early recognition of osteopenia is especially important in pediatric CD. We aimed to identify variables associated with osteopenia to guide dual-energy X-ray absorptiometry (DXA) scan screening to those who most need it.

METHODS

This was a retrospective inception cohort study of children newly diagnosed with CD, and routinely referred to DXA scans. Demographic and explicit clinical data were recorded along with whole-body less head BMD, adjusted for age, sex, and height by z-scores.

RESULTS

Of the 116 included children (mean age 13 ± 3.1 years, 67 [58%] boys, mean body mass index [BMI] 16.7 ± 2.6), 63 (54%) had normal BMD (z-score > -1) or borderline osteopenia (-1 ≥ z-score > -2) and 53 (46%) had osteopenia (z-score ≤ -2). Osteopenia was associated with lower BMI z-score (-0.8 ± 1.2 vs -1.8 ± 1.1, P < 0.001) and higher PCDAI (33.7 ± 15.2 vs 25.7 ± 16.5; P = 0.009) than those with BMD z-score >-2. In total, 59% of children with BMI z-score <-0.5 had moderate-severe osteopenia and only 18% of those with higher z-scores. Multivariate logistic regression identified BMI z-score as the sole risk factor (OR 1.28 [95% CI 1.08-1.52], P = 0.005). BMI z-score ≥-0.5 excludes osteopenia with a sensitivity 87%, specificity 49%, NPV 82%, and PPV 59%.

CONCLUSIONS

Osteopenia was found in nearly half of children with newly onset CD. BMI z-score <-0.5 should prompt referral to DXA screening.

Factors influencing peak bone mass gain

Bone mass is a key determinant of osteoporosis and fragility fractures. Epidemiologic studies have shown that a 10% increase in peak bone mass (PBM) at the population level reduces the risk of fracture later in life by 50%. Low PBM is possibly due to the bone loss caused by various conditions or processes that occur during adolescence and young adulthood. Race, gender, and family history (genetics) are responsible for the majority of PBM, but other factors, such as physical activity, calcium and vitamin D intake, weight, smoking and alcohol consumption, socioeconomic status, age at menarche, and other secondary causes (diseases and medications), play important roles in PBM gain during childhood and adolescence. Hence, the optimization of lifestyle factors that affect PBM and bone strength is an important strategy to maximize PBM among adolescents and young people, and thus to reduce the low bone mass or osteoporosis risk in later life. This review aims to summarize the available evidence for the common but important factors that influence bone mass gain during growth and development and discuss the advances of developing high PBM.

DXA and pQCT derived parameters in Indian children with beta thalassemia major - A case controlled study

Children with beta thalassemia major (BTM) are known to have reduced bone mass which increases incidence of non-traumatic fractures. Few studies have assessed prevalence of fractures and bone health in underprivileged children with BTM. Our objectives were to 1) determine prevalence of fractures in underprivileged Indian children with BTM, 2) assess size corrected bone density and bone geometry using Dual x-ray absorptiometry (DXA) and peripheral quantitative computerized tomography (pQCT) in these children and healthy controls 3) determine predictors of fractures in children with BTM 4) compare differences in bone density between children with BMT with and without fractures. Bone mineral content and areal bone mineral density (aBMD) of lumbar spine and whole body and vertebral fracture assessment (VFA) was performed by DXA in 334 children (3-18 years, 167 BTM + 167 controls). Volumetric BMD (vBMD) and bone geometry were assessed by pQCT (subset, 70 BTM, 70 healthy) at distal radius. Children with BTM had higher prevalence of vertebral and long bone fractures (p < 0.05). DXA aBMD was lower in children with BTM (p < 0.05), whereas, lumbar spine bone mineral apparent density (LSBMAD) was higher (p > 0.05). Children with BTM had lower total distal radial vBMD, cortical vBMD and strength strain index (SSI) at 66% site whereas, distal radial trabecular vBMD at 4% was higher (p < 0.05). On height adjustment, children with BTM had lower muscle area and cortical thickness and higher marrow area (p < 0.05) at 66% site. Age, body size, total body less head (TBLH) aBMD and strength strain index (SSI) were important predictors of fractures in children with BTM. Thus, children with BTM had higher prevalence of non-traumatic fractures. Despite lower areal and volumetric densities, they had higher LSBMAD and trabecular densities which may be attributed to erythroid hyperplasia and iron deposition due to inadequate transfusion and chelation. As LSBMAD is raised in these children, it is unlikely to identify BTM subjects at risk of fracture; VFA thus maybe useful in identifying asymptomatic vertebral fractures.

Effects of Bisphosphonates on Osteoporosis Induced by Duchenne Muscular Dystrophy: A Prospective Study

OBJECTIVE

Duchenne muscular dystrophy (DMD) is a severe X-linked progressive neuromuscular disease that brings a significantly increased risk of osteoporosis and bone fractures. We prospectively evaluated the effects of oral and intravenous bisphosphonates on the bones of children with DMD.

METHODS

This study included a total of 52 children with DMD. They were divided into zoledronic acid (ZOL), alendronate (ALN), and control groups according to bone mineral density (BMD) and history of fragility fractures. For 2 years, all patients took calcium, vitamin D, and calcitriol. Meanwhile, 17 patients received infusions of ZOL, and 18 patients received ALN. BMD, serum levels of alkaline phosphatase (ALP) and the cross-linked C-telopeptide of type I collagen (β-CTX) were evaluated.

RESULTS

After 24 months of treatment, the percentage changes in lumbar spine BMD were 23.2 ± 9.7% and 23.6 ± 8.8% in the ZOL and ALN groups (all P<.01 vs. baseline). The increases did not differ between the ZOL and ALN groups, but were significantly larger than those of the control group (P<.01). Serum β-CTX and ALP levels, respectively, were decreased by 44.4 ± 18.0% and 31.9 ± 26.7% in the ZOL group and by 36.0 ± 20.3% and 25.8 ± 14.4% in the ALN group (all P<.01 vs. baseline).

CONCLUSION

Zoledronic acid and alendronate had similar protective effects to increase bone mineral density and reduce bone resorption in children with DMD, which were superior to treatment of calcium, vitamin D, and calcitriol.

ABBREVIATIONS

25OHD = 25 hydroxyvitamin D; ALN = alendro-nate; ALP = alkaline phosphatase; ALT = alanine aminotransferase; BMD = bone mineral density; BP = bisphosphonate; Ca = calcium; β-CTX = cross-linked C-telopeptide of type I collagen; DMD = Duchenne muscular dystrophy; FN = femoral neck; GC = glucocorticoid; LS = lumbar spine; ZOL = zoledronic acid.

Dual-energy X-ray absorptiometry bone densitometry in pediatrics: a practical review and update

The assessment of pediatric bone mineral content and density is an evolving field. In this manuscript we provide a practical review and update on the interpretation of dual-energy X-ray absorptiometry (DXA) in pediatrics including historical perspectives as well as a discussion of the recently published 2019 Official Position Statements of the International Society of Clinical Densitometry (ISCD) that apply to children.

The "Goldilocks Day" for Children's Skeletal Health: Compositional Data Analysis of 24-Hour Activity Behaviors

Optimization of children's activity behaviors for skeletal health is a key public health priority, yet it is unknown how many hours of moderate to vigorous physical activity (MVPA), light physical activity (LPA), sedentary behavior, or sleep constitute the best day-the "Goldilocks Day"-for children's bone structure and function. To describe the best day for children's skeletal health, we used data from the cross-sectional Child Health CheckPoint. Included participants (n = 804, aged 10.7 to 12.9 years, 50% male) underwent tibial peripheral quantitative CT to assesses cross-sectional area, trabecular and cortical density, periosteal and endosteal circumference, polar moment of inertia, and polar stress-strain index. Average daily time-use composition (MVPA, LPA, sedentary time, and sleep) was assessed through 8-day, 24-hour accelerometry. Skeletal outcomes were regressed against time-use compositions expressed as isometric log-ratios (with quadratic terms where indicated), adjusted for sex, age, pubertal status, and socioeconomic position. The models were used to estimate optimal time-use compositions (associated with best 5% of each skeletal outcome), which were plotted in three-dimensional quaternary figures. The center of the overlapping area was considered the Goldilocks Day for skeletal health. Children's time-use composition was associated with all skeletal measures (all p ≤ 0.001) except cross-sectional area (p = 0.72). Days with more sleep and MVPA, less sedentary time, and moderate LPA were beneficially associated with skeletal measures, except cortical density, which was adversely associated. The Goldilocks daily time-use composition for overall skeletal health was center (range): 10.9 (10.5 to 11.5) hours sleep; 8.2 (7.8 to 8.8) hours sedentary time; 3.4 (2.8 to 4.2) hours LPA, and 1.5 (1.3 to 1.5) hours MVPA. Estimated optimal sleep duration is consistent with current international guidelines (9 to 11 hours), while estimated optimal MVPA exceeds recommendations of at least 60 min/d. This first study to describe optimal durations of daily activities for children's skeletal health provides evidence to underpin guidelines. © 2020 American Society for Bone and Mineral Research (ASBMR).

The effect of an online exercise programme on bone health in paediatric cancer survivors (iBoneFIT): study protocol of a multi-centre randomized controlled trial

BACKGROUND

New approaches on paediatric cancer treatment aim to maintain long-term health. As a result of radiotherapy, chemotherapy or surgery, paediatric cancer survivors tend to suffer from any chronic health condition. Endocrine dysfunction represents one of the most common issues and affects bone health. Exercise is key for bone mass accrual during growth, specifically plyometric jump training. The iBoneFIT study will investigate the effect of a 9-month online exercise programme on bone health in paediatric cancer survivors. This study will also examine the effect of the intervention on body composition, physical fitness, physical activity, calcium intake, vitamin D, blood samples quality of life and mental health.

METHODS

A minimum of 116 participants aged 6 to 18 years will be randomized into an intervention (n = 58) or control group (n = 58). The intervention group will receive an online exercise programme and diet counselling on calcium and vitamin D. In addition, five behaviour change techniques and a gamification design will be implemented in order to increase the interest of this non-game programme. The control group will only receive diet counselling. Participants will be assessed on 3 occasions: 1) at baseline; 2) after the 9 months of the intervention; 3) 4 months following the intervention. The primary outcome will be determined by dual energy X-ray absorptiometry (DXA) and the hip structural analysis, trabecular bone score and 3D-DXA softwares. Secondary outcomes will include anthropometry, body composition, physical fitness, physical activity, calcium and vitamin D intake, blood samples, quality of life and mental health.

DISCUSSION

Whether a simple, feasible and short in duration exercise programme can improve bone health has not been examined in paediatric cancer survivors. This article describes the design, rationale and methods of a study intended to test the effect of a rigorous online exercise programme on bone health in paediatric cancer survivors. If successful, the iBoneFIT study will contribute to decrease chronic health conditions in this population and will have a positive impact in the society.

TRIAL REGISTRATION

Prospectively registered in isrctn.com: isrctn61195625 . Registered 2 April 2020.

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.

Proton pump inhibitor use and risk of hip fracture in patients with type 2 diabetes

Type 2 diabetes mellitus (T2DM) is associated with a high rate of comorbidity, including osteoporosis and peptic ulcers. Proton pump inhibitors (PPIs) are a group of acid-suppressing drugs commonly used for treating peptic ulcers. However, observational studies have reported an association between PPI therapy and osteoporotic fractures. This study investigated the association between PPI use and hip fracture (HFx) among patients with T2DM. We conducted this population-based propensity-matched retrospective cohort study using the National Health Insurance Research Database in Taiwan. Patients newly diagnosed with T2DM between 2000 and 2008 were identified. After excluding those who previously used PPIs or suffered HFx, 398,885 patients were recruited (44,341 PPI users; 354,544 non-users). HFx risk data from 2000 to 2013 were collected to calculate the cumulative rate of HFx in these two groups. Sensitivity analyses were conducted to evaluate the effects of PPI dose. After propensity score matching of 1:4, 44,431 and 177,364 patients were assigned to the PPI user and non-user groups, respectively. PPI user group showed an increased risk of HFx with an adjusted hazard ratio of 1.41 (95% CI 1.29–1.54) without dose–response relationship. Thus, there is an increased risk of HFx in patients with T2DM receiving long-term PPI treatment.

Association between maternal smoking and child bone mineral density: a systematic review and meta-analysis

Maternal smoking during pregnancy has detrimental effects on fetal development. The current review examined the differences in offspring's bone mineral density (BMD) between mothers smoked during pregnancy and those who did not. A systematic review and meta-analysis on the studies investigating the influence of maternal smoking during pregnancy on children or neonates' bone measures published up to October 30, 2018, was performed. BMD results measured at different body sites were pooled and then fixed or random effect models were used based on the presence of heterogeneity. The desired pooled effect size was the offspring's BMD mean difference with 95% confidence interval between smoker and non-smoker mothers. Sensitivity analysis was performed for birth weight and current weight, two important mediator/confounders causing heterogeneity. Overall, eight studies consisting of 17,931 participants aged from infancy to 18 years were included. According to the fixed effect model, the mean of BMD in offspring whose mothers smoked during pregnancy was 0.01 g/cm² lower than those with non-smoker mothers (95% CI = - 0.02 to - 0.002). However, subgroup meta-analysis adjusted for birth weight and current weight demonstrated no significant mean difference between BMD of children with smoker and non-smoker mothers (d = 0.06, 95% CI = -0.04 to 0.16, p value = 0.25 and d = - 0.005, 95% CI = - 0.01 to 0.004, p value = 0.28, respectively). According to available studies, it is suggested that maternal smoking during pregnancy does not have direct effect on the offspring's BMD. Instead, this association might be confounded by other factors such as placental weight, birth weight, and current body size of children.

Bones and Birth Control in Adolescent Girls

Peak bone mass acquisition during adolescence is an important determinant of adult bone health. Knowledge about the effects of different contraceptives on peak bone mass acquisition could influence choice of method recommended. This review summarizes normal bone acquisition during adolescence, discusses methods of assessing bone health in this age group, and reviews the effects of different contraceptive options on bone health, both in adults and in adolescents. Based on the evidence, long-acting reversible contraceptives do not appear to affect peak bone mass acquisition or future fracture risk and remain the first-line contraceptive choice for adolescents. Oral contraceptives with doses of ethinyl estradiol greater than 30 μg should be used in preference to lower-dose preparations, and the adverse effects of depo medroxyprogesterone acetate (DMPA) on bone health are reversible on discontinuation of the medication. Concerns about bone health should not prevent use of DMPA in an adolescent who prefers this method.