Bone mineral density of proximal femur and spine in Korean children between 2 and 18 years of age

Ethnic factors affect bone mass acquisition during childhood. The aim of our study was to establish normative data for bone mineral content (BMC) and bone mineral density (BMD) in healthy Korean children and adolescents, using 446 lumbar spine scans (224 males and 222 females) and 364 proximal femur scans (181 males and 183 females) of healthy children between ages 2 and 18 years measured by dual-energy X-ray absorptiometry using Hologic QDR Discovery A 2004. There was an increase in both BMC and BMD during early childhood, acceleration during the adolescence spurt, and a slower increase later. Until 11 years of age, both male and female BMC and BMD were not statistically different. There was a rapid increase in both BMC and BMD in females earlier than in males, and later males caught up with the females and overshot the female values. When compared with Canadian children, BMD and BMC of total proximal femur was found to be more and BMD and BMC of total lumbar spine to be less at some ages. Tanner's stage was significantly associated with BMD and BMC of spine and proximal femur in males and BMC of spine in females in the first three Tanner's stages. Height, body weight, fat content, and body mass index influenced BMC and BMD at different sites by variable amount. Hence, the values presented in this study should be used as reference values in Korean children and adolescents.     

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.     

Bone mass in young women is dependent on lean body mass.

Relationships between bone mineral density (BMD) and body mass, height, fat mass, and lean mass have been reported. This study examined the relationship between body size and composition on bone density in young premenopausal women. In this study, a cross-sectional design was used. Seventy-one healthy women aged between 24 and 36 yr selected to have a wide range of boy habitus (mean body mass index, 22.7+/-3.0) underwent a dual-energy X-ray absorptiometry (DXA) whole-body bone density scan (Hologic QDR 2000). Their bone density and soft tissue body composition and anthropometric parameters (skinfolds, girths, limb lengths, bone breadths, height, and body mass) were analyzed, and their body composition was assessed by underwater weighing (UWW). Bone-free lean mass (BFLM) determined by DXA was correlated with both bone mineral content (BMC) and BMD (r=0.74, p<0.001; r=0.48, p<0.001, respectively). In addition, fat-free mass (FFM) determined by UWW was correlated with BMC and BMD (r=0.80, p<0.001; r=0.48, p<0.001, respectively). Controlling for height in the model removed most of the correlations with whole-body BMD, with the exception of FFM, BFLM, and shoulder breadth (r=0.39, p<0.001; r=0.37, p<0.01; and r=0.34, p<0.01, respectively). No correlation was found between fat mass by DXA, UWW, and sum of skinfolds and BMD. These results indicate that bone mass in premenopausal women is dependent on lean body mass.     

Simulated change in body fatness affects Hologic QDR 4500A whole body and central DXA bone measures.

Changes in body fatness may impact the accuracy of dual energy X-ray absorptiometry (DXA) measures of bone mineral content (BMC) and bone mineral density (BMD). The aim of this study was to determine if DXA can accurately assess BMC and BMD with changes in exogenous fat (lard) placed to simulate weight change. Whole body (WB), lumbar spine (LS), and proximal femur (PF) DXA scans (Hologic QDR 4500A) were performed on 30 elderly (52-83 yr) and 60 young (18-40 yr) individuals (i.e., 45 females and 45 males) of varying body mass index (mean+/-standard deviation: 26.1+/-4.9 kg/m2). When scans were repeated with lard packets (2.54 cm thick, 25.4x17.8 cm, 1 kg), WB BMD decreased 1.1% and 1.6% after chest and thigh packet placement, respectively (p=0.001), PF BMD increased 0.7% (p=0.02) and LS BMD decreased 1.6% (p=0.001) primarily due to a 2.2% reduction in LS BMC (p<0.001). Initial LS BMC and trunk mass were related to error in LS BMC measures due to lard-loading (r=0.64 and 0.45, respectively, p<0.001). We conclude that on average simulated weight change minimally impacts PF bone measures and moderately impacts WB and LS bone measures; however, individual variability in measurement error was noteworthy and may be impacted by body thickness.     

Is Osteopenia a Health Risk in Professional Cyclists?

Bone mineral content (BMC) and bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry Lunar DPX-NT, SV 4.0 in 23 professional male cyclists (age: 28.5+/-3.9 yr; height: 179+/-6.8 cm; weight: 70.9+/-7.1 kg(-1)). Eight subjects had normal L1-L4 T-score values (-0.19+/-0.62) and 15 had low values (-1.57+/-0.45). Correlations between: L1-L4 T-scores and body weight, fat mass (FM) and % FM (r=0.40, p<0.05; r=0.65, p<0.001; r=0.59, p<0.01). Regression analysis: L1-L4 T-score and FM (R2=0.42; p<0.001); total BMC and fat-free mass (FFM) (R2=0.60; p<0.0001); and total BMD and BMI (R2=0.25; p<0.05). Climbers had lower arms BMD (0.85+/-0.04; p<0.05). Flat-terrain cyclist had lower right leg FFM (9.7+/-0.8 kg; p<0.05). Time trialists had higher body weight (76.7+/-4.4 kg; p<0.05), total FFM (68.3+/-4.7 kg), total BMC (3.1+/-0.3; p<0.03), right and left leg BMC (0.60+/-0.1; 0.60+/-0.1; p<0.05), and spinal BMD (1.09+/-0.1; p<0.05). In conclusion, two-thirds of professional cyclists had abnormally low BMD values.     

Can BMD assessed by DXA at age 8 predict fracture risk in boys and girls during puberty?: an eight-year prospective study.

This study reports on the association between DXA at age 8 and subsequent fractures in both male and female children. Bone densitometry at the total body and spine (but not hip) is a strong predictor of fracture (especially upper limb) during puberty. INTRODUCTION: The aim of this study was to determine if prepubertal DXA can predict fracture risk during puberty. MATERIALS AND METHODS: We studied 183 children who were followed for 8 yr (1460 person-years). Bone densitometry was measured at the total body, hip, and spine by DXA and reported as BMC, BMD, and bone mineral apparent density (BMAD). Fractures were self-reported at age 16 with X-ray confirmation, RESULTS: There were a total of 63 fractures (43 upper limb). In unadjusted analysis, only total body BMD showed an inverse relationship with upper limb fracture risk (p = 0.03). However, after adjustment for height, weight, age (all at age 8), and sex, total body BMC (HR/SD, 2.47; 95% CI, 1.52-4.02), spine BMC (HR/SD, 1.97: 95% CI, 1.30-2.98), total body BMD (HR/SD, 1.67; 95% CI, 1.18-2.36), total body BMAD (HR/SD, 1.54; 95% CI, 1.01-2.37), and spine BMD (HR/SD, 1.53; 95% CI, 1.10, 2.22) were all significantly associated with upper limb fracture risk. Similar, but weaker associations were present for total fractures. There was a trend for overweight/obesity to be associated with increased upper limb fracture risk (HR, 1.53/category; p = 0.08). CONCLUSIONS: Measurement of bone mass by DXA is a good predictor of upper limb fracture risk during puberty. Although we did not measure true BMD, the constancy of fracture prediction after a single measure suggests bone strength remains relatively constant during puberty despite the large changes in bone size.     

Muscle strength is a determinant of bone mineral content in the hemiparetic upper extremity: implications for stroke rehabilitation

Individuals with stroke have a high incidence of bone fractures and approximately 30% of these fractures occur in the upper extremity. The high risk of falls and the decline in bone and muscle health make the chronic stroke population particularly prone to upper extremity fractures. This was the first study to investigate the bone mineral content (BMC), bone mineral density (BMD), and soft tissue composition of the upper extremities and their relationship to stroke-related impairments in ambulatory individuals with chronic stroke (onset >1 year). Dual-energy X-ray absorptiometry (DXA) was used to acquire total body scans on 56 (22 women) community-dwelling individuals (>or=50 years of age) with chronic stroke. BMC (g) and BMD (g/cm2), lean mass (g), and fat mass (g) for each arm were derived from the total body scans. The paretic upper extremity was evaluated for muscle strength (hand-held dynamometry), impairment of motor function (Fugl-Meyer motor assessment), spasticity (Modified Ashworth Scale), and amount of use of the paretic arm in daily activities (Motor Activity Log). Results showed that the paretic arm had significantly lower BMC (13.8%, P<0.001), BMD (4.5%, P<0.001), and lean mass (9.0%, P<0.001) but higher fat mass (6.3%, P=0.028) than the non-paretic arm. Multiple regression analysis showed that lean mass in the paretic arm, height, and muscle strength were significant predictors (R2=0.810, P<0.001) of the paretic arm BMC. Height, muscle strength, and gender were significant predictors (R2=0.822, P<0.001) of lean mass in the paretic arm. These results highlight the potential of muscle strengthening to promote bone health of the paretic arm in individuals with chronic stroke.     

Pediatric reference data for bone mineral density in the calcaneus for healthy children 2, 4, and 7 years of age by dual-energy x-ray absorptiometry and laser.

Dual-energy X-ray absorptiometry and laser (DXL) Calscan measures bone mineral density (BMD) in the calcaneus. In the present study, the DXL Calscan device has been modified for use in pediatric practice. It includes a function for measuring calcaneal height, which makes it possible to calculate volumetric bone mineral apparent density (BMAD). The aims of the present study were to evaluate the method when used in children, to create pediatric reference values in healthy Swedish 2-, 4-, and 7-yr-old children for BMD, bone mineral content (BMC), and BMAD, and to study whether these parameters were related to auxological data. The method was well tolerated by all children. Intraindividual coefficients of variation for BMC and BMD decreased with increasing age. The mean BMD was 0.17+/-0.003 g/cm2 in 2-yr-old children, 0.22+/-0.003 g/cm2 in 4-yr-old children, and 0.30+/-0.005 g/cm2 in 7-yr-old children. This study provides normative data as percentile values for BMD, BMC, and BMAD in young children measured with DXL Calscan. BMD was significantly correlated with age (p<0.001), height (p=0.001), weight (p<0.001), and body mass index standard deviation score (p<0.001). Seven-year-old girls showed significantly higher BMD than boys.     

Bone density interpretation and relevance in Caucasian children aged 9-17 years of age: insights from a population-based fracture study.

The interpretation of bone density measurement in children is difficult due to a number of factors including rapid change in body size and uncertain clinical significance of bone density in children. This study asked two questions. (1) Is there a preferred bone density measurement site or type for fracture risk in children? (2) What is the best way to interpret bone density in children? This population-based case control study included 321 upper limb fracture cases and 321 class- and sex- matched randomly selected controls. Bone density at the hip, spine, and total body (including the arm) was measured by a Hologic QDR2000 densitometer (Waltham, MA) and examined as bone area (BA), bone mineral content (BMC), bone mineral density (BMD), bone mineral apparent density (BMAD), and BMC/lean mass (BMCLM). The only dual-energy X-ray absorptiometry (DXA) variables that were consistently associated with fracture risk in both boys and girls were spine BMD and BMAD for total upper limb fractures, and spine and hip BMAD for wrist and forearm fractures. No significant associations were observed for BA and BMCLM and inconsistent associations for BMC and other BMD sites. Five-yr fracture risk varied from 15–24% depending on site and gender in a child with a Z-score of -3. In the controls, all DXA variables were associated with age, height, and weight, but the weakest associations were with BMAD. In conclusion, in this study the spine BMAD had the strongest and most consistent association with upper limb fracture risk in children. The associations with age and body size imply that age specific Z-scores will be the most convenient for interpretation of DXA measures in children. Five-yr wrist and forearm fracture risk has potential as a clinical endpoint of immediate relevance.     

Relative contribution of vertebral body and posterior arch in female and male lumbar spine peak bone mass

Peak bone mass (PBM) is an important reference value in the diagnosis of osteoporosis. It is usually established by determining the areal bone mineral density (BMD in g/cm²) for a given site of the skeleton in young healthy adults. This measurement takes into account both the thickness and the integrated mineral density of the bone scanned. It should therefore be a major determinant of the resistance to mechanical stress. However, in lumbar spine the mean BMD as determined by dual-energy either isotopic or X-ray (DXA) absorptiometry in antero-posterior (ap) view was repeatedly found not to be different between male and female young healthy adults despite the greater volume of lumbar vertebral bodies in males. A greater contribution of the posterior vertebral arch to areal BMD-ap in females than in males could account for such an apparent discrepancy. In order to clarify this issue we have determined in 65 (32 male and 33 female) young healthy adults aged 20–35 years the relative contribution of the vertebral body (VB) and posterior vertebral arch (VA) to BMD and bone mineral content (BMC) of L2–3 measured by both antero-posterior and lateral (lat) scanning using DXA. In young healthy adults mean BMC in antero-posterior view was found not to be significantly different from the total BMC determined by lateral scanning including both VB and VA. This allowed us then to calculate the VA BMC by substracting VB BMC-lat from BMC-ap. The results indicated that the mean value for males was significantly greater than that for females for BMC-ap (male/female ratio (mean±SEM): 1.16±0.05,p<0.01), BMC-lat (1.38±0.07,p<0.001) and VB BMD-lat (1.16±0.04,p<0.001). In sharp contrast, no sex difference was found in BMD-ap (male/female ratio: 0.99±0.03) and VA BMC (male/female ratio: 0.97±0.06). VA BMC represented 44% and 53% (p<0.001) of BMC-ap in males and females, respectively. Furthermore, in neither sex was any correlation between VA BMC and VB BMC found. In summary, this study indicates that the relative contribution of the posterior vertebral arch to the bone mineral content of L2–3 is significantly smaller in males than in females. This difference could partly explain the absence of a sex difference in areal BMD as measured in antero-posterior view. In agreement with lumbar anthropomorphometric data this study further shows that the sex difference in vertebral body size, an important component in mechanical resistance, is expressed when areal BMD is measured in lateral but not in antero-posterior scanning. Finally, the data analysis underlines the quantitative importance of the vertebral arch in the value of areal BMD as measured by DXA in the classical antero-posterior view, and demonstrates the absence of a significant quantitative relationship between the bone mineral content of the vertebral body and that of the posterior vertebral arch.     

Pamidronate preserves bone mass for at least 2 years following acute administration for pediatric burn injury

We have previously shown that pamidronate, when given within 10 days of burn injury, preserves lumbar spine bone mineral content from admission to discharge in 6-8 weeks and at 6 months increases both lumbar spine and total body bone mineral content (BMC) over placebo. We followed patients unblinded after 6 months every 3 months up to 2 years post-burn to see if the effects of pamidronate were sustained. Additionally, we assessed bone remodeling at 1 year post-burn by iliac crest bone biopsy. We enrolled 57 subjects who were initially randomized to pamidronate (n=32) and placebo (n=25). After 2 years, 21 subjects (pamidronate=8, placebo=13) remained. Analysis of bone densitometry by dual energy X-ray absorptiometry revealed an effect of both treatment (p<0.012 for total body BMC, p<0.001 for lumbar spine BMC, p<0.014 for lumbar spine bone area and p<0.003 for lumbar spine bone density (BMD)) and time (p<0.0003 on total body BMC, p<0.001 on lumbar spine BMC, p<0.001 on lumbar spine bone area, and no significant difference on lumbar spine BMD). There was no interaction between treatment and time. Results for bone histomorphometry revealed no effect of treatment on either static or dynamic parameters but did show an effect of time on osteoid area (p=0.004, surface p<0.001, and width, p<0.001). We conclude that acute administration of pamidronate resulted in sustained therapeutic effect on bone and that this type of administration may serve as a useful adjunct to other therapies in the preservation and augmentation of bone mass following severe burns.     

Males have larger skeletal size and bone mass than females, despite comparable body size.

Gender differences in fractures may be related to body size, bone size, geometry, or density. We studied this in 18-year-old males (n = 36) and females (n = 36) matched for height and weight. Despite comparable body size, males have greater BMC and BMD at the hip and distal tibia and greater tibial cortical thickness. This may confer greater skeletal integrity in males. INTRODUCTION: Gender differences in fractures may be related to body size, bone size, geometry, or density. We studied this in males (n = 36) and females (n = 36; mean age = 18 years) pair-matched for height and weight. MATERIALS AND METHODS: BMC, bone area (BA), and BMD were measured in the spine and hip using DXA. Distal tibia was measured by pQCT. RESULTS AND CONCLUSIONS: Males had a higher lean mass (92%) compared with females (79%). No gender differences were observed for vertebral BMC or vertebral height, although males had greater width and thus BA at the spine. Males had greater BMC and BA at the femoral neck and total femur (p < 0.02). Geometric variables of the hip including neck diameter and neck-axis length were also greater in males (p < 0.02). There was greater cross-sectional moment of inertia, safety factor, and fall index in males (all p < 0.02). Males had greater tibial BMC, volumetric BMD, and cortical area and thickness compared with females (p < 0.01), with both greater periosteal circumference (p = 0.011) and smaller endosteal circumference (p = 0.058). Statistically controlling for lean mass reduced gender differences, but males still had 8% higher hip BMD (p = 0.24) and 5.3% higher total tibial BMD (p = 0.05). A subset of males and females were matched (n = 14 pairs) for total hip BA. Males in this subset still had greater BMC and BMD at the total hip (p < 0.05) than females, despite similar BA. In summary, despite comparable body size, males have greater BMC and BMD than females at the hip and distal tibia but not at the spine. Differences in BMC and BMD were related to greater cortical thickness in the tibia. We conclude that differences in bone mass and geometry confer greater skeletal integrity in males, which may contribute to the lower incidence of stress and osteoporotic fractures in males.     

Genetics of Bone Mass in Childhood and Adolescence: Effects of Sex and Maturation Interactions

We aimed to determine if adult bone mineral density (BMD) susceptibility loci were associated with pediatric bone mass and density, and if sex and pubertal stage influenced any association. We analyzed prospective areal BMD (aBMD) and bone mineral content (BMC) data from the Bone Mineral Density in Childhood Study (n = 603, European ancestry, 54% female). Linear mixed models were used to assess if 77 single‐nucleotide polymorphisms (SNPs) near known adult BMD susceptibility loci interacted with sex and pubertal stage to influence the aBMD/BMC; adjusting for age, BMI, physical activity, and dietary calcium. The strongest main association was observed between an SNP near C7orf58 and distal radius aBMD. However, this association had a significant sex?SNP interaction, revealing a significant association only in females (b = –0.32, p = 1.8 × 10^–6). Furthermore, the C12orf23 locus had significant interactions with both sex and pubertal stage, revealing associations in females during Tanner stage I for total hip aBMD (b = 0.24, p = 0.001) and femoral neck aBMD (b = 0.27, p = 3.0 × 10^–5). In contrast, the sex?SNP interactions for loci near LRP5 and WNT16 uncovered associations that were only in males for total body less head BMC (b = 0.22, p = 4.4 × 10^–4) and distal radius aBMD (b = 0.27, p = 0.001), respectively. Furthermore, the LRP5 locus interacted with both sex and pubertal stage, demonstrating associations that were exclusively in males during Tanner V for total hip aBMD (b = 0.29, p = 0.003). In total, significant sex?SNP interactions were found at 15 loci; pubertal stage?SNP interactions at 23 loci and 19 loci interacted with both sex and pubertal stage. In conclusion, variants originally associated with adult BMD influence bone mass in children of European ancestry, highlighting the fact that many of these loci operate early in life. However, the direction and magnitude of associations for a large number of SNPs only became evident when accounting for sex and maturation. © 2015 American Society for Bone and Mineral Research.     

Collagen Ialpha1 polymorphism is associated with bone characteristics in Caucasian children and young adults

A large proportion of the variation in bone mass can be explained by genetic factors. We analyzed the G to T substitution in the Sp1 binding site in the first intron of the collagen type Ialpha1 (COLIA1) gene in relation to bone mass. The genotypes GG, GT, and TT were determined in 148 Caucasian children and young adults. We performed dual energy X-ray absorptiometry twice (mean follow-up time 4.4 years), and speed of sound (SOS) was assessed by tibial ultrasonometry at follow-up. Genotype distribution was 104 (70%) GG, 40 (27%) GT and 4 (3%) TT. Carriers of the T-allele had a 0.5 SDS (standard deviation score) decreased bone mineral content (BMC) of total body (P = 0.001), and a 0.4 SDS decreased bone mineral density (BMD) for both lumbar spine (P = 0.04) and total body (P = 0.05). The genotype effect on BMD and BMC decreased after adjustment for height or body mass index. When we calculated apparent BMD, these differences diminished to 0.1 SDS and were no longer significant. T-allele carriers had shorter stature (0.4 SDS; P = 0.04) and smaller bones (0.5 SDS lower width of the lumbar vertebral body; P = 0.01). The T-allele was also associated with lower SOS (P = 0.03), independent of BMD and BMC, and lower lean body mass. Similar associations were found at follow-up. The change in BMD and BMC SDS between the first and second measurement did not differ between the GG and GT&TT group. In conclusion, the COLIA1 polymorphism in children and young adults is associated with several bone characteristics. However, at least a part of the COLIA1 effect on bone mass may be related to differences in frame size.     

力学负荷对峰值骨量影响的初步研究

目的 人的运动器官含骨量的多少与外力有关。本实验研究了重力、肌力对骨量的影响。方法 排除了继发性骨质疏松，用DXA对男56例、女55例受试测量全身骨量，收集BMC、BMD、体重、瘦体重指标。结果 发现全身体重和瘦体重与BMC呈密切相关，与BMD的相关较弱。女性的相关强于男性，男女相同体重配对后，男性的BMC、瘦体重、握力分别大于女性3．5％、27．8％、44％。这可能是男性力学性能优于女性的重要原因，而且男性体重每大于女性1kg其BMC较女性增加0．020kg；男性瘦体重每大于女性1kg其BMC较女性增加0．008kg；体重和肌力都是决定BMC的因素，体重可能是决定BMC的重要外力。结论 应该进一步研究骨质疏松诊断中如何发挥骨力学的优越性。     

Intensive exercise may preserve bone mass of the upper limbs in spinal cord injured males but does not retard demineralisation of the lower body

STUDY DESIGN: Cross-sectional study comparing a group of active spinal cord injured (SCI) males carefully matched for age, height, and weight with active able-bodied male controls. OBJECTIVES: To compare bone mass of the total body, upper and lower limbs, hip, and spine regions in active SCI and able-bodied individuals. SETTING: Outpatient study undertaken in two centres in New Zealand. METHODS: Dual energy X-ray absorptiometry (DEXA) scanning was used to determine bone mass. Questionnaires were used to ascertain total time spent in weekly physical activity for each individual. The criterion for entry into the study was regular participation in physical activity of more than 60 min per week, over and above that required for rehabilitation. RESULTS: Seventeen SCI and their able-bodied controls met our required activity criterion. Bone mineral density (BMD) values of the total body and hip regions were significantly lower in the SCI group than in their controls (P=0.0001). Leg BMD and bone mineral content (BMC) were also significantly lower in the SCI group (P=0.0001). By contrast, lumbar spine BMD and arm BMD and BMC did not differ between the SCI and control groups. Arm BMD and BMC were greater (not significant) than the reference norms (LUNAR database) for both groups. CONCLUSION: Intensive exercise regimens may contribute to preservation of arm bone mass in SCI males, but does not prevent demineralisation in the lower body.     

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.     

Relation of forearm's bone and soft tissues to infant's body composition.

Small portable units using the dual X-ray absorptiometry method (pDEXA) are becoming available to evaluate a localized region of the body such as the forearm. The purpose of this study was to evaluate the relationship between infant's forearm measurements of bone mineral, lean, and fat mass and total body composition. Twenty-two infants participated in this study. Mean age of the infants was 21 d with a weight range of 1-3.6 kg. All infants were stable and had their forearm and total body scanned on the same day. The long-term precision error for the pDEXA was 0.4%. The infant's total body was scanned by the XR-26 (Norland Medical Systems, Fort Atkinson,WI). Forearm bone mineral content, bone mineral density (BMD), fat mass, and lean mass correlated to total body mineral content (BMC) (r = 0.84, p < 0.001), total body BMD (r = 0.73, p < 0.001), total fat mass (r = 0.53, p < 0.05), and total body lean mass (r = 0.80, p < 0.001). Forearm BMC, lean, and fat mass correlated significantly with body weight and length (r = 0.73-0.94). In conclusion, forearm measurements of bone mineral, fat, and lean mass reflect total body bone mineral, fat, and lean mass in small infants.     

High bone mass in a female Hutterite population.

We examined a Hutterite population (n = 243) to determine if their agriculturally diverse, self-sufficient communal lifestyle promotes optimal bone mass attainment because of adequate calcium intake and high physical activity levels during growth and young adulthood. We measured total body (TB) and lumbar bone mineral content (BMC) and bone mineral density (BMD) in 39 school-age (younger) females and 204 working (older) females. Forty-five percent of older females and 79% of younger females currently consumed > or = 3 servings (svg) of dairy per day. Older females had lumbar (0.6 +/- 1.3) and TB (1.1 +/- 1.1) BMD Z scores greater than 0 (both, p < 0.001). The lumbar BMD Z score of younger females was not different from 0 (-0.1 +/- 1.0; p = 0.5). Both lumbar (r = 0.46; p < 0.001) and TB (r = 0.20; p = 0.02) BMD Z scores increased with increasing age. In multiple regression analyses for older females, lumbar bone area (p < 0.001), weight (p < 0.001), current hours on feet per day (p = 0.01), colony workload (p < 0.01), and estrogen status (p = 0.06) predicted lumbar BMC. TB bone area (p < 0.001), current hours on feet per day (p < 0.001), and colony workload (p < 0.01) predicted TB BMC. For younger females, lumbar bone area (p < 0.001), weight (p < 0.01), years in present colony (p = 0.02), and menses (p < 0.001) predicted lumbar BMC. TB bone area (p < 0.001), height (p < 0.01), years in present colony (p = 0.03), and menses (p < 0.01) predicted TB BMC. The effect of colony workload could not be separated from other factors different by colony. A heritability estimate of 0.66 was calculated for lumbar BMD using mother and daughter Z scores. Adequate calcium intake during growth, high physical activity early in life, and genetic factors may be contributing to above normal BMD levels in adult female Hutterites.     

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.