Relationships between the lean mass index and bone mass and reference values of muscular status in healthy Chinese children and adolescents

This study aimed to analyze the relationships between the lean mass index (LMI) and bone outcomes in Chinese children and adolescents using dual-energy X-ray absorptiometry (DXA) and to establish sex-specific reference percentile curves for the assessment of muscle status. A total of 1541 Chinese children and adolescents between the ages of 5 and 19 years were recruited from southern China. Body composition was measured by DXA (Lunar Prodigy) to acquire total body and total body less head (TBLH) measures. LMI was calculated as the LM (kg) divided by the height in meters squared. Strong sex gaps were observed after age 14 in total body LMI and appendicular LMI (p < 0.001). LM and LMI values continued to increase for boys up to age 14 compared to girls who plateaued after age 12. For each sex group, total body bone mineral content (BMC) and TBLH BMC were highly correlated with total body LMI and appendicular LMI (r = 0.856–0.916 in boys, and r = 0.651–0.804 in girls, p < 0.001). The appendicular LMI was more strongly associated with total body BMC and TBLH BMC than was total body LMI. The correlations between the BMC values and the LM measures were stronger than the fat mass results. We also present sex-specific percentile curves for LM–age and LMI–age relationships, which could be useful for identifying the LM deficits in this population.     

Femur neck bone mineral density and fracture risk by age,sex, and race or Hispanic origin in older US adults from NHANES III

Summary

We provide the first reference values for bone mineral content and bone mineral density according to age and sex in Iranian children and adolescents. The prevalence of hypovitaminosis D was high, and levels of physical activity were low in our sample. Multiple regression analyses showed age, BMI, and Tanner stage to be the main indicators of bone mineral apparent density.

Purpose

Normal bone structure is formed in childhood and adolescence. The potential determinants which interact with genetic factors to influence bone density include gender, nutritional, lifestyle, and hormonal factors. This study aimed to evaluate bone mineral content (BMC) and the bone mineral density (BMD) and factors that may interfere with it in Iranian children.

Methods

In this cross-sectional study, 476 healthy Iranian children and adolescents (235 girls and 241 boys) aged 9–18 years old participated. BMC and BMD of the lumbar spine, femoral neck, and total body were measured by dual-energy X-ray absorptiometry using a Hologic Discovery device, and bone mineral apparent density (BMAD) of the lumbar spine and the femoral neck were calculated.

Results

We present percentile curves by age derived separately for BMC, BMD, and BMAD of the lumbar spine, left femoral neck, and total body excluding the head for boys and girls. Maximum accretion of BMC and BMD was observed at ages of 11–13 years (girls) and 12–15 years (boys).The prevalence of hypovitaminosis D was high and physical activity was low in our participants. However, in multiple regression analyses, age, BMI, and Tanner stage were the main indicators of BMD and BMAD

Conclusion

These normative data aid in the evaluation of bone density in Iranian children and adolescents. Further research to evaluate the evolution of BMD in Iranian children and adolescents is needed to identify the reasons for significant differences in bone density values between Iranian populations and their Western counterparts.     

Bone mass and density in preadolescent boys with and without Down syndrome

Summary

Preadolescent boys with Down syndrome at 7–10 years of age have lower bone mass and density in the pelvis than age-matched children without Down syndrome. However, bone mass and density of total body less head and lumbar spine are not different between these two groups.

Introduction

This study aimed to assess bone mineral content (BMC) and density (BMD) in preadolescent boys with and without Down syndrome (DS) at 7–10 years of age.

Methods

Eleven preadolescent boys with DS and eleven age-matched children without DS participated in this study. Dual-energy X-ray absorptiometry was used to measure BMC and BMD in whole body and lumbar spine. Both BMC and BMD of total body less head (TBLH) and lumbar spine (vertebrae L2–L4) were compared between the two groups, with and without adjusting for physical characteristics such as bone area, body height, and total lean mass. Two bone mineral apparent density (BMAD) variables were calculated to estimate volumetric BMD in the lumbar spine.

Results

Both BMC and BMD in the pelvis were lower in the DS group, after adjusting for physical characteristics. However, with and without adjusting for physical characteristics, the two groups were not different in BMC and BMD of the arms, legs, and TBLH from the whole body scan and in BMC, BMD, and BMAD of the lumbar spine from the lumbar spine scan.

Conclusions

These findings indicate that the pelvis may be the first site to show the significant difference in BMC and BMD between preadolescent boys with and without DS. It also suggests that significantly lower BMC and BMD in whole body and lumbar spine, which is usually observed in young adults with DS, may not occur before adolescence.     

Normal reference for bone density in healthy Chinese children.

An ethnicity- and gender-specific normal reference database is necessary for the clinical dual-energy X-ray absorptiometry (DXA) assessment of skeletal status in Chinese children. We used a Lunar Prodigy DXA densitometer to measure bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) at total body and subcranial skeleton for 877 healthy Chinese children (505 boys, 372 girls) aged 5-13 yr. The height-for-age, BA-for-height, and BMC-for-BA percentile curves were developed using the LMS method (L, power in Box-Cox transformation; M, median; S, coefficient of variation). We found that total body BMD and subcranial skeleton BMD were highly correlated (r=0.701-0.949), and that total body BMD was significantly higher than subcranial skeleton BMD for each gender and age group (p<0.001). No gender differences in total body and subcranial skeleton BMD were found. Total body lean mass correlated highly with total body BMC and subcranial skeleton BMD and BMC (boys: r=0.888-0.953, girls: r=0.917-0.967) and moderately with total body BMD (boys: r=0.684, girls: r=0.777). The head region accounted for 16-52% and 16-49% of the total body BMC in boys and girls, respectively, and the percentages were negatively correlated with age (boys: r=-0.824, girls: r=-0.864) and height (boys: r=-0.911, girls: r=-0.922). Regression analyses showed that age explained more variance in subcranial skeleton BMD (boys: R(2)=0.641, girls: R(2)=0.685) than in total body BMD (boys: R(2)=0.387, girls: R(2)=0.472). In summary, we have presented an ethnicity- and gender-specific densitometric normal reference database for Chinese children aged 5-13 yr. It should allow for an appropriate clinical assessment of total body bone density in Chinese children as measured by the Lunar Prodigy DXA densitometer.     

Optimal monitoring time interval between DXA measures in children

The monitoring time interval (MTI) is the expected time in years necessary to identify a change between two measures that exceeds the measurement error. Our purpose was to determine MTI values for dual‐energy X‐ray absorptiometry (DXA) scans in normal healthy children, according to age, sex, and skeletal site. 2014 children were enrolled in the Bone Mineral Density in Childhood Study and had DXA scans of the lumbar spine, total hip, nondominant forearm, and whole body. Measurements were obtained annually for seven visits from 2002 to 2010. Annualized rates of change were calculated by age and sex for all bone regions. A subgroup of 155 children ages 6 to 16 years (85 boys) had duplicate scans for calculation of scan precision. The bone mineral density (BMD) regions of interest included the spine, total body less head (TBLH), total hip, femoral neck, and one‐third radius. Bone mineral content (BMC) was also evaluated for the spine and TBLH. The percent coefficient of variation (%CV) and MTI were calculated for each measure as a function of age and sex. The MTI values were substantially less than 1 year for the TBLH and spine BMD and BMC for boys ≤ 17 years and girls ≤ 15 years. The hip and one‐third radius MTIs were generally 1 year in the same group. MTI values as low as 3 months were found during the peak growth years. However, the MTI values in late adolescence for all regions were substantially longer and became nonsensical as each region neared the age for peak bone density. All four DXA measurement sites had reasonable (< 1 year) MTI values for boys ≤ 17 years and girls ≤ 15 years. MTI was neither useful nor stable in late adolescence and young adulthood. Alternative criteria to determine scan intervals must be used in this age range. © 2011 American Society for Bone and Mineral Research     

Bone mineral density by age, gender, pubertal stages, and socioeconomic status in healthy Lebanese children and adolescents

Gender, ethnicity, and lifestyle factors affect bone mass acquisition during childhood, thus the need for age- and sex-adjusted Z scores using ethnic-specific data for bone mineral density (BMD) measurement. This study aimed at establishing normative data for BMD in healthy Lebanese children and adolescents. Three hundred sixty-three healthy children aged 10 to 17 years (mean+/-SD: 13.1+/-2.0) were studied. BMD, bone mineral content (BMC), and lean mass were measured by dual-energy X-ray absorptiometry (DXA) using a Hologic 4500A device, and apparent volumetric BMD (BMAD) of the lumbar spine and the femoral neck were calculated. BMD, BMC, and BMAD were expressed by age groups and Tanner stages for boys and girls separately. There was a significant effect of age and puberty on all bone parameters, except at the femoral neck BMAD in boys. BMC and BMD were higher at cortical sites in boys, including subtotal body and hip; whereas, in girls, it was higher at a site more enriched in trabecular bone, namely the lumbar spine. At several skeletal sites, girls had significantly higher BMD adjusted for lean mass than boys. By the end of puberty, adolescents had a mean BMD that was 43-66% higher at the lumbar spine and 25-41% higher at cortical sites than pre-pubertal children, depending on the gender. Mean BMD values in the study group were significantly lower (P<0.01) than Western normative values, with Z scores ranging between -0.2 and -1.1. In both genders, children of lower socioeconomic status tended to have lower BMD than those from a higher socioeconomic background. This study allows additional insight into gender dimorphism in mineral accretion during puberty. It also provides a valuable reference database for the assessment of BMD in children with pubertal or growth disorders who are of Middle Eastern origin.     

A Cross-Calibration Study of GE Lunar iDXA and GE Lunar DPX Pro for Body Composition Measurements in Children and Adults

Objective: To cross-calibrate dual energy X-ray absorptiometry machines when replacing GE Lunar DPX-Pro with GE Lunar iDXA. Methods: A cross-sectional study was conducted in 126 children (3–19 years) and 135 adults (20–66 years). Phantom cross calibration was carried out using aluminum phantom provided with each of the machines on both machines. Total body less head (TBLH), lumbar spine (L2–L4) and left femoral neck bone mineral density (BMD), bone mineral content (BMC), and bone area were assessed for each patient on both machines. TBLH lean and fat mass were also measured. Bland-Altman analysis, linear regressions, and independent sample t test were performed to evaluate consistency of measurements and to establish cross-calibration equations. Results: iDXA measured 0.33% lower BMD and 0.64% lower BMC with iDXA phantom as compared to DPX-Pro phantom (p < 0.001). In children, TBLH-BMC, femoral BMC and area were measured 10%–14% lesser, TBLH area was higher by 1%–2% and L2–L4 area by 10%–14% by iDXA as compared to DPX-Pro. iDXA measured higher TBLH fat [15% (girls), 31% (boys)] than DPX-Pro. In adults, TBLH-BMD (1.7%–3.4%), BMC (6.0%–10.9%) and area (4.2%–7.6%) were measured lesser by iDXA than DPX-Pro. L2–L4 BMD was higher [2.7% (men), 1.8% (women)] by iDXA than DPX-Pro. Femoral BMC was 2.11% higher in men and 4.1% lower in women by iDXA as compared to DPX-Pro. In children, R² of cross-calibration equations, ranged from 0.91 to 0.96; in adults, it ranged from 0.93 to 0.99 (p < 0.01). After the regression equations were applied, differences in BMD values between both machines were negligible. Conclusion: A strong agreement for bone mass and body composition was established between both machines. Cross-calibration equations need to be applied to transform DPX-Pro measurements into iDXA measurements to avoid errors in assessment. This study documents a need for use of cross-calibration equations to transform DPX-Pro body composition data into iDXA values for clinical diagnosis.     

The correlation between calcaneus stiffness index calculated by QUS and total body BMD assessed by DXA in Chinese children and adolescents

Few studies have shown comparison data between calcaneus stiffness index (SI) calculated by quantitative ultrasound (QUS) and bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) in the Chinese population. This study was aimed to examine the correlations between calcaneus SI calculated by QUS and total body BMD and bone mineral content (BMC) measured by DXA in Chinese children and adolescents. We measured the total body BMD and BMC using Lunar Prodigy (GE Healthcare), and speed of sound (SOS), broadband ultrasound attenuation (BUA), and a calculated SI of the left os calcis using Lunar Achilles Express (GE Healthcare) in 392 healthy Chinese schoolchildren and adolescents aged 5–19 years. The short-term precision for DXA was 0.5 % for total body BMD. The precision for QUS was 1.8 % for SI, 2.9 % for BUA, and 0.4 % for SOS. Pearson’s correlation coefficients (r) were calculated to assess the possible correlations between the total body BMC by DXA and SI calculated by QUS. There were significantly positive correlations between SI of the left os calcis and total body BMD (r = 0.693, p < 0.001, n = 392) and BMC (r = 0.690, p < 0.001, n = 392). For all the subjects, significant positive correlations were observed between the calcaneal SI and the age, weight, height, BMI, total body BMD, total body BMC, total body lean mass, and total body fat mass, with r ranging from 0.310 (total body fat mass) to 0.693 (total body BMD) (p < 0.001, n = 392). In conclusion, QUS bone densitometry is a useful measuring method showing the physiological bone development in childhood and adolescence.     

Percentile distributions of bone measurements in Iowa children: the Iowa Bone Development Study.

Four hundred twenty-eight white children (200 boys and 228 girls) ages 4.5-6.5 yr had spine, hip, and whole-body bone mineral density (BMD) and bone mineral content (BMC) measured by dual-energy X-ray absorptiometry(DXA) as part of the Iowa Bone Development Study. Anthropometric measurements, including height, weight, and body mass index (BMI) were determined for each child at the time the bone measurements were made. The age- and gender-specific height percentile based on the 2000 CDC Growth Charts (www.cdc.gov/growthcharts/) was determined for each child. These percentiles were used to classify children into four groups as defined by the 25th, 50th,and 75th percentile cutpoints. Percentile distributions were determined within each height quartile group to delineate percentiles (5th, 25th, 50th, 75th, 95th) for BMD and BMC. Gender differences in BMD and BMC were investigated before and after stratification into height groups. Boys had higher age-height-weight-adjusted means for most BMD and BMC measures except spine BMD. Bone measurements increased with height quartile, indicating that taller children have greater BMD and BMC compared to shorter children of the same age and gender. Within any given quartile,mean BMD and BMC measurements were similar for boys and girls, with the exception of hip BMD, for which values were consistently higher for boys (p < 0.05). In addition, whole-body BMC values were higher for boys in quartiles 1 and 3 (p < 0.05). These bone measures provide norms for young white children and serve as a reference for comparison with other racial and ethnic groups, as well as with childhood populations that are at risk for osteopenia because of chronic disease. Gender, age, and height are useful clinical predictors of BMD and BMC in young children.     

Diagnostic evaluation of bone densitometric size adjustment techniques in children with and without low trauma fractures

Summary

Several established methods are used to size adjust dual-energy X-ray absorptiometry (DXA) measurements in children. However, there is no consensus as to which method is most diagnostically accurate. All size-adjusted bone mineral density (BMD) values were more diagnostically accurate than non-size-adjusted values. The greatest odds ratio was estimated volumetric BMD for vertebral fracture.

Introduction

The size dependence of areal bone density (BMD_a) complicates the use of DXA in children with abnormal stature. Despite several size adjustment techniques being proposed, there is no consensus as to the most appropriate size adjustment technique for estimating fracture risk in children. The aim of this study was to establish whether size adjustment techniques improve the diagnostic ability of DXA in a cohort of children with chronic diseases.

Methods

DXA measurements were performed on 450 children, 181 of whom had sustained at least one low trauma fracture. Lumbar spine (L₂–L₄) and total body less head (TBLH) Z-scores were calculated using different size adjustment techniques, namely BMD_a and volumetric BMD for age (bone mineral apparent density (BMAD)); bone mineral content (BMC) and bone area for height; BMC for bone area; BMC for lean mass (adjusted for height); and BMC for bone and body size.

Results

Unadjusted L₂–L₄ and TBLH BMD_a were most sensitive but least specific at distinguishing children with fracture. All size adjustments reduced sensitivity but increased post-test probabilities, from a pre-test probability of 40 % to between 58 and 77 %. The greatest odds ratio for fracture was L₂–L₄ BMAD for a vertebral fracture and TBLH for lean body mass (LBM) (adjusted for height) for a long bone fracture with diagnostic odds ratios of 9.3 (5.8–14.9) and 6.5 (4.1–10.2), respectively.

Conclusion

All size adjustment techniques improved the predictive ability of DXA. The most accurate method for assessing vertebral fracture was BMAD for age. The most accurate method for assessing long bone fracture was TBLH for LBM adjusted for height.     

Regional and total body bone mineral content,bone mineral density,and total body tissue composition in children 8–16 years of age

Summary Normative values for total body bone mineral content (TBBM) and total body bone mineral density (TBMD) were derived from measurements on 234 children 8–16 years of age. In addition, bone mineral content (BMC) and bone mineral density (BMD) values for selected regions of interest and soft tissue (bone free lean and fat) for the total body are presented. Bone mineral and soft tissue values were determined by dual energy X-ray absorptiometry (DXA) using a Hologic QDR-2000 in the array mode. Results of a stepwise multiple regression analysis revealed a significant correlation between bone-free lean tissue (BFLT) and BMD (r² = 0.80) in girls. Adding age to the equation accounted for an additional 2% of the variance (P < 0.05) and height accounted for another 1% of the variance (P < 0.05). Body weight and fat tissue (FT) did not account for any additional variance. In boys BFLT correlated significantly with BMD (r² = 0.75;P < 0.05); none of the other predictor variables accounted for additional variance. No significant differences were found in TBBM or TBMD between boys and girls at any age. There was a significant overall gender effect for only three regions of interest. Boys had greater BMC in the head region and had greater BMD in the upper limbs, but post hoc analysis revealed no significant differences for any specific age groups. Girls had greater overall BMD in the pelvis, but this difference was only significant at the 15–6-year age group. The changes in BFLT and FT over the age ranges were consistent with the growth literature.The normative values can be applied to the assessment of children and adolescents with health problems that may impact on the skeleton as well as to research studies investigating bone mineral development in children.     

Normative data and percentile curves for Dual Energy X-ray Absorptiometry in healthy Indian girls and boys aged 5-17 years

For the correct interpretation of Dual Energy X-ray Absorptiometry (DXA) measurements in children, the use of age, gender, height, weight and ethnicity specific reference data is crucially important. In the absence of such a database for Indian children, the present study aimed to provide gender and age specific data on bone parameters and reference percentile curves for the assessment of bone status in 5-17 year old Indian boys and girls. A cross sectional study was conducted from May 2006 to July 2010 on 920 (480 boys) apparently healthy children from schools and colleges in Pune City, India. The GE-Lunar DPX Pro Pencil Beam DXA scanner was used to measure bone mineral content (BMC [g]), bone area (BA [cm(2)]) and bone mineral density (BMD [g/cm(2)]) at total body, lumbar spine and left femur. Reference percentile curves by age were derived separately for boys and girls for the total body BMC (TBBMC), total body BA (TBBA), lumbar spine bone mineral apparent density (BMAD [g/cm(3)]), and left femoral neck BMAD. We have also presented percentile curves for TBBA for height, TBBMC for TBBA, LBM for height and TBBMC for LBM for normalizing bone data for Indian children. Mean TBBMC, TBBA and TBBMD were expressed by age groups and Tanner stages for boys and girls separately. The average increase in TBBMC and TBBA with age was of the order of 8 to 12% at each age group. After 16 years of age, TBBMC and TBBA were significantly higher in boys than in girls (p<0.01). Maximal increase in TBBMD occurred around the age of 13 years in girls and three years later in boys. Reference data provided may be used for the clinical assessment of bone status of Indian children and adolescents.     

Bone Densitometry in Canadian Children 8–17 Years of Age

Normative bone mineral density (BMD) and bone mineral content (BMC) values for the total body (TB), proximal femur (PF), and antero-posterior lumbar spine (LS) were obtained from a large cross-sectional sample of children and adolescents who were 8–17 years of age. There were 977 scans for the TB, 892 for the PF, and 666 for the LS; bone mineral values were obtained using a HOLOGIC QDR 2000 in array mode. Data are presented for the subregions of the PF (femoral neck, trochanter, intertrochanter, and the total region) and for the LS (L1–L4 and L3). Female and male values for the FN, LS (L1–L4), and the TB were compared across age groups using a two-way ANOVA. In addition, we compared the 17-year-old female values to a separate sample of young adult women (age 21). At all these sites, BMC and BMD increased significantly with age. There was no gender difference in TB BMC until age 14 or in TB BMD until age 16, when male values were significantly greater. Females had significantly greater LS BMC at ages 12 and 13, but by age 17 the male values were significantly greater. Females had significantly greater LS BMD across all age groups, however. Males had significantly greater FN BMC and BMD across all age groups. There were no significant differences in BMC or BMD at any sites between the 17- and 21-year-old women. Received: 29 September 1995 / Accepted: 1 April 1996     

A Pediatric Bone Mass Scan Has Poor Ability to Predict Adult Bone Mass: A 28-Year Prospective Study in 214 Children

As the correlation of bone mass from childhood to adulthood is unclear, we conducted a long-term prospective observational study to determine if a pediatric bone mass scan could predict adult bone mass. We measured cortical bone mineral content (BMC [g]), bone mineral density (BMD [g/cm²]), and bone width (cm) in the distal forearm by single photon absorptiometry in 120 boys and 94 girls with a mean age of 10 years (range 3–17) and mean 28 years (range 25–29) later. We calculated individual and age-specific bone mass Z scores, using the control cohort included at baseline as reference, and evaluated correlations between the two measurements with Pearson’s correlation coefficient. Individual Z scores were also stratified in quartiles to register movements between quartiles from growth to adulthood. BMD Z scores in childhood and adulthood correlated in both boys (r = 0.35, p < 0.0001) and girls (r = 0.50, p < 0.0001) and in both children ≥10 years at baseline (boys r = 0.43 and girls r = 0.58, both p < 0.0001) and children <10 years at baseline (boys r = 0.26 and girls r = 0.40, both p < 0.05). Of the children in the lowest quartile of BMD, 58 % had left the lowest quartile in adulthood. A pediatric bone scan with a value in the lowest quartile had a sensitivity of 48 % (95 % confidence interval [CI] 27–69 %) and a specificity of 76 % (95 % CI 66–84 %) to identify individuals who would remain in the lowest quartile also in adulthood. Childhood forearm BMD explained 12 % of the variance in adult BMD in men and 25 % in women. A pediatric distal forearm BMD scan has poor ability to predict adult bone mass.     

Physical Activity Benefits the Skeleton of Children Genetically Predisposed to Lower Bone Density in Adulthood

Both genetics and physical activity (PA) contribute to bone mineral density (BMD), but it is unknown if the benefits of physical activity on childhood bone accretion depend on genetic risk. We, therefore, aimed to determine if PA influenced the effect of bone fragility genetic variants on BMD in childhood. Our sample comprised US children of European ancestry enrolled in the Bone Mineral Density in Childhood Study (N = 918, aged 5 to 19 years, and 52.4% female). We used a questionnaire to estimate hours per day spent in total, high‐, and low‐impact PA. We calculated a BMD genetic score (% BMD lowering alleles) using adult genome‐wide association study (GWAS)‐implicated BMD variants. We used dual‐energy X‐ray absorptiometry to estimate femoral neck, total hip, and spine areal‐BMD and total body less head (TBLH) bone mineral content (BMC) Z‐scores. The BMD genetic score was negatively associated with each bone Z‐score (eg, TBLH‐BMC: estimate = –0.03, p = 1.3 × 10^?6). Total PA was positively associated with bone Z‐scores; these associations were driven by time spent in high‐impact PA (eg, TBLH‐BMC: estimate = 0.05, p = 4.0 × 10^?10) and were observed even for children with lower than average bone Z‐scores. We found no evidence of PA‐adult genetic score interactions (p interaction > 0.05) at any skeletal site, and there was no evidence of PA‐genetic score–Tanner stage interactions at any skeletal site (p interaction > 0.05). However, exploratory analyses at the individual variant level revealed that PA statistically interacted with rs2887571 (ERC1/WNT5B) to influence TBLH‐BMC in males (p interaction = 7.1 × 10^?5), where PA was associated with higher TBLH‐BMC Z‐score among the BMD‐lowering allele carriers (rs2887571 AA homozygotes: estimate = 0.08 [95% CI 0.06, 0.11], p = 2.7 × 10^?9). In conclusion, the beneficial effect of PA on bone, especially high‐impact PA, applies to the average child and those genetically predisposed to lower adult BMD (based on GWAS‐implicated BMD variants). Independent replication of our exploratory individual variant findings is warranted. © 2016 American Society for Bone and Mineral Research.     

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

This is the first prospective cohort study of the association between bone mass and fracture risk in childhood. A total of 6213 children 9.9 years of age were followed for 24 months. Results showed an 89% increased risk of fracture per SD decrease in size-adjusted BMC. INTRODUCTION: Although previous case-control studies have reported that fracture risk in childhood is inversely related to bone mass, this has not been confirmed in prospective studies. Additionally, it remains unclear which constituent(s) of bone mass underlie this association. We carried out a prospective cohort study to examine the relationship between DXA measures in children 9.9 years of age and risk of fracture over the following 2 years. MATERIALS AND METHODS: Total body DXA scan results obtained at 9.9 years of age were linked to reported fractures over the following 2 years in children from a large birth cohort in southwest England. DXA measures consisted of total body less head (TBLH) BMD, bone area, and BMC, and results of subregional analysis of the humerus. Analyses were adjusted for age, sex, ethnicity, and social position. RESULTS: Complete data were available on 6213 children. There was a weak inverse relationship between BMD at 9.9 years and subsequent fracture risk (OR per SD decrease = 1.12; 95% CI, 1.02-1.25). In analyses examining the relationship between fracture risk and volumetric BMD, fracture risk was inversely related to BMC adjusted for bone area, height, and weight (OR = 1.89; 95% CI, 1.18-3.04) and to estimated volumetric BMD of the humerus (OR = 1.29; 95% CI, 1.14-1.45). Fracture risk was unrelated to both TBLH and humeral bone area. However, in analyses of the relationship between fracture risk and bone size relative to body size, an inverse association was observed between fracture risk and TBLH area adjusted for height and weight (OR = 1.51; 95% CI, 1.17-1.95). CONCLUSIONS: Fracture risk in childhood is related to volumetric BMD, reflecting an influence of determinants of volumetric BMD such as cortical thickness on skeletal fragility. Although bone size per se was not related to fracture risk, we found that children who fracture tend to have a smaller skeleton relative to their overall body size.     

Sex-specific relationships between insulin resistance and bone mineral content in Korean adolescents

The aim of this study was to examine sex-specific relationships between insulin resistance (IR) and bone mineral content (BMC) according to age group and weight status. A population-based sample of 618 Korean adolescents (315 male and 303 female), aged 10–19 years from the Fourth Korea National Health and Nutrition Examination Survey, 2009. They were divided into three age groups (10–12; 13–16; 17–19 years) and two weight groups (non-overweight vs. overweight). IR was assessed using the homeostatic model of assessment of IR (HOMA-IR). Soft tissue composition (fat and lean mass) and BMC of the whole body, proximal femur, and lumbar spine were measured by dual energy X-ray absorptiometry. Adiposity (body mass index, waist circumference, or soft tissue composition), age, height, total cholesterol, triglycerides, high density lipoprotein cholesterol, alkaline phosphatase, serum vitamin D, dietary calcium and energy intake, and menarche for females were adjusted using general linear models of a complex sampling design. Higher HOMA-IR was associated with a decrease in BMC in male adolescents aged 13–19 years after adjustment for adiposity and other confounders, while the associations were not significant in male adolescents aged 10–12 years and female adolescents. After adjustment for adiposity and confounders, the inverse associations between HOMA-IR and BMC were more consistent in non-overweight male adolescents than in other weight groups (overweight males and non-overweight and overweight females). The unfavorable effect of IR on BMC appears to be more obvious in males aged 13–19 years or non-overweight males than in females.     

A 5-Year Exercise Program in Pre- and Peripubertal Children Improves Bone Mass and Bone Size Without Affecting Fracture Risk

We studied the effect in children of an exercise intervention program on fracture rates and skeletal traits. Fractures were registered for 5 years in a population-based prospective controlled exercise intervention study that included children aged 6–9 years at study start, 446 boys and 362 girls in the intervention group and 807 boys and 780 girls in the control group. Intervention subjects received 40 min/school day of physical education and controls, 60 min/week. In 73 boys and 48 girls in the intervention group and 52 boys and 48 girls in the control group, bone mineral density (BMD, g/cm²) and bone area (mm²) were followed annually by dual-energy X-ray absorptiometry, after which annual changes were calculated. At follow-up we also assessed trabecular and cortical volumetric BMD (g/cm³) and bone structure by peripheral computed tomography in the tibia and radius. There were 20.0 fractures/1,000 person-years in the intervention group and 18.5 fractures/1,000 person-years in the control group, resulting in a rate ratio of 1.08 (0.79–1.47) (mean and 95 % CI). The gain in spine BMD was higher in both girls (difference 0.01 g/cm², 0.005–0.019) and boys (difference 0.01 g/cm², 0.001–0.008) in the intervention group. Intervention girls also had higher gain in femoral neck area (difference 0.04 mm², 0.005–0.083) and at follow-up larger tibial bone mineral content (difference 0.18 g, 0.015–0.35), larger tibial cortical area (difference 17 mm², 2.4–31.3), and larger radial cross-sectional area (difference 11.0 mm², 0.63–21.40). As increased exercise improves bone mass and in girls bone size without affecting fracture risk, society ought to encourage exercise during growth.     

Bone-related complications of transfusion-dependent beta thalassemia among children and adolescents

Thalassemia and the blood transfusion complications associated with it predispose children to poor bone health. This study was conducted to determine the prevalence of bone-related abnormalities and identify the bone health predictors within this population. One hundred and forty transfusion-dependent beta thalassemic subjects 8–18 years old in Mashhad, Iran, participated in this cross-sectional study. Anthropometric measures, dietary intake, bone-related biomarkers and bone densitometry, were assessed. The incidence of underweight and short stature was 33.6 and 41.4 %, respectively, which were indicators of malnutrition among thalassemic subjects in this study. Low bone density was detected in the lumbar spine and femoral region in 82 and 52 % of subjects, respectively. Hypocalcemia and hypophosphatemia were seen in 22 and 18.2 %, whilst vitamin D deficiency was present in more than 85 % of thalassemic children and adolescents. The relationships between weight, height and other anthropometric indices, serum calcium and bone markers, intake of macronutrients, zinc and vitamin E with bone mineral density (BMD) and bone mineral content (BMC) in the lumbar spine and femoral area were positively related, indicating that better nutritional status were associated with higher BMD and BMC values. Puberty, gender and serum osteocalcin were negative predictors for BMD and BMC values, whereas age, weight and height were the positive predictors. High incidence of low bone density and deficit in other aspects of bone health among thalassemia patients makes routine bone health assessment necessary for this vulnerable group. Considering influencing factors, dietary counseling and preventive supplementation therapy for this high risk group of children and adolescents may be necessary, although this should be assessed by intervention studies.     

A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children: the university of Saskatchewan bone mineral accrual study.

To investigate the influence of physical activity on bone mineral accrual during the adolescent years, we analyzed 6 years of data from 53 girls and 60 boys. Physical activity, dietary intakes, and anthropometry were measured every 6 months and dual-energy X-ray absorptiometry scans of the total body (TB), lumbar spine (LS), and proximal femur (Hologic 2000, array mode) were collected annually. Distance and velocity curves for height and bone mineral content (BMC) were fitted for each child at several skeletal sites using a cubic spline procedure, from which ages at peak height velocity (PHV) and peak BMC velocity (PBMCV) were identified. A mean age- and gender-specific standardized activity (Z) score was calculated for each subject based on multiple yearly activity assessments collected up until age of PHV. This score was used to identify active (top quartile), average (middle 2 quartiles), or inactive (bottom quartile) groups. Two-way analysis of covariance, with height and weight at PHV controlled for, demonstrated significant physical activity and gender main effects (but no interaction) for PBMCV, for BMC accrued for 2 years around peak velocity, and for BMC at 1 year post-PBMCV for the TB and femoral neck and for physical activity but not gender at the LS (all p < 0.05). Controlling for maturational and size differences between groups, we noted a 9% and 17% greater TB BMC for active boys and girls, respectively, over their inactive peers 1 year after the age of PBMCV. We also estimated that, on average, 26% of adult TB bone mineral was accrued during the 2 years around PBMCV.