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     

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 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.     

Comparison of bone mineral content among Japanese, Koreans, and Taiwanese assessed by dual-photon absorptiometry.

Throughout the world the diagnosis and management of osteoporosis currently involves the measurement of bone mineral content. There are, however, no studies comparing bone mineral content among Asian people. This cross-sectional study was designed to quantify spine and femur bone mineral density (BMD) in Japanese and compare BMD among Asian people (Japanese, Koreans, and Taiwanese) using the same model dual-photon system (Norland Model 2600). Following a peak BMD in the third and fourth decades, the Japanese BMD values of the lumbar spine and femoral neck showed a clear decrease (annual loss of 0.99 and 0.74%, respectively) with age in females. On the other hand, Japanese BMD values were stable in males until the fifth decade. There was some decrease in BMD with age after the fifth decade, which was much less obvious than that in females. An age-dependent loss of BMD was clearly observed in Japanese and Korean but not in Taiwanese females. Korean males seemed to have a clearer age-dependent loss of BMD compared to Japanese males. Our findings indicate that differences may exist in the BMD of Asian people and that in addition to the quantitative determination of individual BMD, dual-photon absorptiometry may be useful for the comparison of BMD among different ethnic and cultural groups.     

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.     

Longitudinal measurement of regional and whole body bone mass in young healthy adults

The so-called peak bone mass (PBM) represents the highest amount of bony tissue achieved during life at a given site of the skeleton. It has been suggested that PBM might be achieved as late as the fourth decade, but recent data have indicated that PBM is already achieved by the end of sexual maturation, namely at the end of the second decade. The solving of this apparent controversy is of interest for a better understanding of bone homeostasis and for defining the cohort of normal subjects to be evaluated in order to establish a PBM reference range — necessary for the diagnosis of osteoporosis and evaluation of the fracture risk. To study bone mass evolution in young healthy adults and to determine whether such a cohort can be used to establish PBM reference values, we measured bone mineral density (BMD) in sixty 20- to 35-year-old young healthy adults by dual-energy X-ray absorptiometry at the levels of the lumbar spine (in both anteroposterior and lateral views), femoral neck, trochanter region, total hip and of Ward's triangle, as well as whole-body BMD and bone mineral content (BMC) in cross-sectional and longitudinal studies. In the cross-sectional analysis, none of the bone mass variables was dependent on age using linear regression analysis. The longitudinal study indicated that the mean changes in lumbar spine, proximal femur and whole body BMD or BMC determined after a 1-year interval were not statistically different from zero in either females or males aged 20–35 years. In conclusion, the present results confirm that at the levels of lumbar spine and proximal femur, two sites particularly at risk of osteoporotic fractures, PBM can be achieved before the third and fourth decades in both male and female normal subjects.     

Sex differences in bone mass acquisition during growth: the Fels Longitudinal Study.

Risk of osteoporosis in later life may be determined during adolescence and young adulthood. The present study used longitudinal data to examine the accumulation of bone mineral content (BMC) and bone mineral density (BMD) in Caucasian subjects ages 6-36 yr. Growth in BMC and BMD (measured by dual X-ray absorptiometry; Lunar, Madison, WI) of 94 males and 92 females was monitored for a mean period of 4.29 yr. The main findings were that there were no sex differences in BMC or BMD during the prepubertal stage; however, females had significantly higher BMD of the pelvis and BMC and BMD of the spine during puberty, and postpubertal males generally had significantly higher BMC and BMD than their female counterparts. In addition, the longitudinal rate of bone accumulation in both sexes increased rapidly during childhood and adolescence and was nearly complete at the end of puberty. Finally, peak BMC and BMD was achieved between the ages of 20 and 25 and occurred earlier in females than in males. The rates of growth and timing of peak bone mass as reported here define the crucial period during which intervention protocols should be developed for maximizing skeletal mass to prevent the development of osteoporosis.     

广州地区1 403例成年女性骨密度测定分析

目的了解本地区成年女性人群腰椎、股骨近端各部位骨密度(Bone mineral density BMD)随年龄、绝经年限、体重、身高的变化规律、各部位骨密度的偏相关分析和多元线性回归分析及骨质疏松患病率情况,为骨质疏松的诊断及预防提供科学依据.方法采用美国NORLAND公司的XR-46系列双能X线骨密度仪测量1 403例成年女性人群腰椎(L2-L4前后位及L3侧位)、非优势(左)股骨近端各部位(股骨颈、大粗隆及Ward's三角)BMD值,按10岁一个年龄组分7组对数据进行统计分析.结果广州地区成年女性腰椎骨峰含量出现在30～39岁组,而股骨近端骨峰含量出现在20～29岁组,腰椎及股骨近端各部位BMD值均随年龄增长而下降,腰椎和Ward's三角部位在50～59岁和60～69岁两年龄组骨量呈快速丢失现象.各部位骨密度的偏相关分析显示各部位的骨密度均呈相关性(P＜0.01).多元线性回归分析显示年龄和体重对绝经前女性股骨颈的骨密度有影响(P＜0.01),而绝经后女性腰3侧位骨密度除了年龄和体重的影响外,身高和绝经年限均对其有影响(P＜0.01).成年女性在达到峰值骨量后随着年龄的增加,各部位骨质疏松的患病率都呈上升趋势.结论女性机体BMD随年龄而变化,年龄、体重、绝经年限及身高等对机体BMD均有一定的影响,保持合适的体重和体型,有利于BMD的增加与维持.对不同年龄段的成年女性人群,预防骨质疏松的发生应以测量不同部位的BMD作为评价手段.     

Differences in estimates of change of bone accrual and body composition in children because of scan mode selection with the prodigy densitometer.

Girls of age 10-13 yr with Tanner stage I-III maturation status (n = 155) were measured using the Prodigy (GE Lunar) densitometer. Bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) were assessed for the whole body, lumbar spine, and proximal femur using the Thin (T) and Standard (S) scan modes at years 1 and 3 of the study. The differences obtained between the T and S mode at year 1 were 1-2% for the lumbar spine and proximal femur and 5-11% for the whole body. For those girls whose default mode changed from T at year 1 to S mode at year 3, the estimated gain in BA, BMC, and BMD was 3.4%, 7.6%, and 3.1% respectively, lower than that obtained when scanning with the T mode at both times for the whole body. Small changes in magnitude but large intersubject variability were noted in BA, BMC, and BMD of the lumbar spine and proximal femur when scanned with the default mode of T at year 1 and S at year 3 compared to T or S at both years. Errors of this size are comparable to the changes expected with longitudinal intervention studies and are, therefore, clinically relevant.     

Relationship between bone mineral density of the proximal femur and lumbar spine and quadriceps and hamstrings torque in healthy Japanese subjects

The purpose of this study was to examine the corelations between the muscle torque of the leg extensors (quadriceps femoris) and leg flexors (Hamstrings) and the bone mineral density (BMD) of the proximal femur and lumbar spine. To investigate the decline in BMD of proximal femur and lumbar spine, we examined the relative importance of muscle torque, age, and body weight in the prediction of BMD in 340 healthy volunteers (109 males, and 231 females). Age and body weight were independent predictors of femoral BMD in men. Body weight and quadriceps torque were independent predictors of femoral BMD in premenopausal women. Body weight and years after menopause were independent predictors of BMD in postmenopausal women. The BMD was greatly affected by menopause, whereas the muscle torque was independent of the menopause, and showed the negative relationship to age. These results suggest that muscle-building exercise may have the potentiality to elevate the BMD in the proximal femur in premenopausal women.     

Nandrolone decanoate and intranasal calcitonin as therapy in established osteoporosis

This study used a randomized, 2 × 2 factorial design to evaluate over 2 years the effect of intranasal salmon calcitonin and intramuscular nandrolone decanoate on bone mass in elderly women with established osteoporosis. The study was double masked in relation to calcitonin and open in relation to nandrolone decanoate. One hundred and twenty-three women aged 60–88 years who had sustained a previous osteoporotic fracture, or had osteopenia, were recruited through an outpatient clinic. Women were assigned to one of four groups: (1) daily placebo nasal spray, (2) 400 IU intranasal calcitonin daily, (3) 20 intramuscular injections of 50 mg nandrolone decanoate (given as two courses of 10 injections) plus placebo nasal spray, or (4) 20 injections of 50 mg nandrolone decanoate plus 400 IU intranasal calcitonin daily. All subjects received 1000 mg calcium supplementation daily. Outcomes measured included changes in bone mineral density (BMD) at the lumbar spine, as measured by dual-energy quantitative computed tomography (DEQCT), in BMD of the proximal femur, and BMD and bone mineral content (BMC) of the lumbar spine and forearm, as measured by dual-energy X-ray absorptiometry (DXA). Significant positive changes from baseline in DXA BMC at the lumbar spine were observed over 2 years in the calcitonin group (5.0±1.9%, mean ± SE) and in the nandrolone deconate group (4.7±1.9%) but not in the placebo group (1.1±2.2%) or the combined therapy group (0.7±1.8%). Modelling based on the 2×2 factorial design revealed that nandrolone decanoate was associated with a 3.8±1.8% (p<0.05) gain in DXA BMD at the proximal femur. Modelling also revealed that calcitonin treatment was associated with a loss of 11.5±4.7% in DEQCT BMD at the lumbar spine and a loss of 3.7±1.8% in DXA BMD at the proximal femur (p<0.05). There was in vivo antagonism between the two medications of 7.9±3.9% for DXA BMC at the lumbar spine. Both agents caused positive changes from baseline in lumbar spine BMC. Nandrolone decanoate had beneficial effects on BMD at the proximal femur. This dose of intranasal calcitonin was associated with deleterious effects on trabecular BMD at the lumbar spine and total BMD at the proximal femur. There may be significant clinical antagonism between these two medications.     

云南昆明地区正常人群骨矿密度研究

目的 了解本地区正常人群腰椎，髋部各部位骨密度（BMD）的年龄变化规律；建立当地骨矿密度正常值标准。方法 1998－2000年间，采用美国Lunar公司生产的Expert型双能骨密度仪（DEXA）测量年龄在20－90岁之间的706例正常人腰椎及股骨近端骨密度值。每10岁为1个年龄组，共分为男女各7个组。数据用SPSS统计软件包进行统计分析。结果 ①男女两性均于30－39岁达到骨峰值；此后随年龄的增长，骨矿密度逐渐开始下降（80岁以上组除外）。②第一腰椎的骨峰值较第四腰椎低（P＜0．01）；③80岁以上组骨密度出现反向增高，特别是在腰椎。结论 ①昆明的高海拔（1800－2000米）造成的低气压和缺氧环境以及云南人的身高和体重普遍较北方人低，造成其骨密度均值低于北方人；②昆明正常人群的骨密度明显高于成都。则可能是由于昆明日照时间（平均2522小时／年）较长的缘故；③80岁以上年龄组骨矿密度受到骨质退变、软组织钙化的影响，在诊断骨质疏松时，应同时检测两个以上区域；并参考同一受检区域不同部位的值。     

Gender differences in bone density at different skeletal sites of acquisition with age in Chinese children and adolescents

Bone mass acquisition from different genders and races of children and adolescents may vary. To explore gender- and age-related differences in bone mineral density (BMD) measurements in Chinese children and adolescents, we used the dual-energy X-ray absorptiometry (DXA) bone densitometer to take BMD measurements at the posteroanterior (PA) and lateral spine, hip, and forearm in 1286 healthy children and adolescents, ranging from 6 to 24 years of age. Our results show a correlation between BMD measurements taken from different skeletal sites and from different ages of subjects. Male data were best fit to a power regression model, yielding the largest determinant coefficients (R ²), whereas S regression was the best fitting model for females. In individuals younger than 17 years of age, the rate of BMD accumulation in the PA spine is more rapid in females than in males, whereas in individuals older than 19 years of age, the converse was found to be true. In children younger than 14 years of age, BMD measurements, taken from the lateral spine, the neck and trochanter of the femur, and the total hip, correlated with age similarly in both genders. Additionally, in measurements taken from the forearm ultradistal and 1/3 region, BMD measurements from similar ages of both genders are similar. With increasing age, BMD measurements in males become significantly higher than those of females. However, volumetric BMD (vBMD) measurements from both genders show good uniformity at the lateral spine with a near overlap of the two models. Our findings suggest that vBMD acquisition measurements in Chinese children and adolescents show no gender differences, with gender differences only demonstrated in areal BMD (aBMD) measurements taken from different skeletal sites.     

Body composition and bone density reference data for Korean children,adolescents, and young adults according to age and sex: results of the 2009–2010 Korean National Health and Nutrition Examination Survey (KNHANES)

We established the timing of peak bone mass acquisition and body composition maturation and provide an age- and sex-specific body composition and bone density reference database using dual-energy X-ray absorptiometry in Korean subjects 10–25 years of age. Reference percentiles and curves were developed for bone mineral content (BMC), bone mineral density (BMD) of the whole body, the lumbar spine, and the femoral neck, and for fat mass (FM) and lean mass (LM) of 1969 healthy participants (982 males) who participated in the 2009–2010 Korean National Health and Nutrition Examination Survey. Additionally, bone mineral apparent density (BMAD), FM index, and LM index were calculated to adjust for body size. BMC and BMD at all skeletal sites as well as LM increased with age, reaching plateaus at 17–20 years of age in females and 20–23 years of age in males. The femoral neck was the first to reach a bone mass plateau, followed by the lumbar spine and then the whole body. Spine BMAD increased with age in both sexes, but femoral and whole-body BMAD remained the same over time. Females displayed a dramatic increase in FM during puberty, but the FM of males decreased until mid-puberty. These findings indicate that bone health and body composition should be monitored using a normal reference database until the late second to early third decade of life, when statural growth and somatic maturation are completed.     

Supralesional and sublesional bone mineral density in spinal cord-injured patients

This study was performed to evaluate supra- and sublesional bone mineral density (BMD) in spinal cord-injured (SCI) patients after 1 year postinjury, and to correlate the BMD to the neurological level; to correlate the sublesional demineralization to functional parameters (duration postinjury, duration of the initial bedrest); and to assess the role of classic methods of prevention such as walking or standing. Thirty-one SCI patients, all male, were studied vs. 31 controls (age matched). The mean age of the population was 36 years (range 18-60 years). Eleven were tetraplegic and 20 were paraplegic. Twenty-six patients dysplayed a complete motor lesion. The BMD was measured by dual-photon absorptiometry on the lumbar spine and on the femoral neck, and the bone mineral content (BMC) on whole-body scans. Particular attention was paid to the distal femur and proximal tibia upper third. Blood samples and urine samples included phosphocalcic parameters, with determination of urinary hydroxyproline and deoxypyridinoline. SCI patients showed a decrease of sublesional BMD of 41% in comparison with controls. This loss of bone mass is higher at the distal femur (-52%) and proximal tibia (-70%), which are the most common sites of fracture. The degree of demineralization for the lumbar spine, the pelvis, and the lower limbs is independent of the neurological level. The duration of acute posttraumatic immobilization (mean 43.3 days) and the time postinjury increase the loss of bone mass for lower limbs (p = 0.04) and particularly for the proximal tibia (p = 0.02). The study of biomechanical stress (i.e., standing, walking, sitting) does not influence the sublesional BMC. This study underlines the major role of the neurological lesion on the decrease of sublesional BMC in SCI patients and the absence of influence of biomechanical stress.     

The effects of gonadectomy on bone size, mass, and volumetric density in growing rats are gender-, site-, and growth hormone-specific.

Peak volumetric bone mineral density (BMD) is determined by the growth in bone size relative to the mineral accrued within its periosteal envelope. Thus, reduced peak volumetric BMD may be the result of reduced mineral accrual relative to growth in bone size. Because sex steroids and growth hormone (GH) influence bone size and mass we asked: What are the effects of gonadectomy (Gx) on bone size, bone mineral content (BMC), areal and volumetric BMD in growing male and female rats? Does GH deficiency (GH-) reduce the amount of bone in the (smaller) bone, i.e., reduce volumetric BMD? Does GH- alter the effect of Gx on bone size and mineral accrual? Gx or sham surgery was performed at 6 weeks in GH- and GH replete (GH+) Fisher 344 male and female rats. Changes in bone size, volume, BMC, areal and volumetric BMD, measured using dual X-ray absorptiometry (DPX-L), were expressed as percentage of controls at 8 months (mean +/- SEM). All results shown were significant (p < 0.05 level) unless otherwise stated. In GH+ and GH- males, respectively, Gx was associated with: lower femur volume (24%, 25%), BMC (43%, 45%), areal BMD (21%, 14%), and volumetric BMD (30%, 28%); lower spine (L1-L3) volume (26%, 28%), BMC (26%, 30%), and areal BMD (28%, 12%), but not volumetric BMD. Following Gx, GH+ females had increased femur volume (11%), no effect on BMC, decreased areal BMD (6%) and decreased volumetric BMD (17%); GH- females had no change in femur volume, but decreased femur BMC (24%), areal BMD (10%), and volumetric BMD (25%). In GH+ and GH- females, respectively, Gx was associated with a decrease in spine (L1-L3) BMC (12%, 15%), areal BMD (16%, 15%), and volumetric BMD (10%, 16%) with no change in volume. Deficits in non-Gx GH- relative to non-Gx GH+ (males, females, respectively) were: femur BMC (49%, 37%), areal BMD (23%, 8%), volume (19%, 19%) and volumetric BMD (37%, 22%); spine (L1-L3) BMC (46%, 42%), areal BMD (37%, 43%), volume (10%, 15%), and volumetric BMD (40%, 33%). Testosterone and GH are growth promoting in growing male rats, producing independent effects on bone size and mass; deficiency produced smaller appendicular bones with reduced volumetric BMD because deficits in mass were greater than deficits in size. At the spine, the reduction in size and accrual were proportional, resulting in a smaller bone with normal volumetric BMD. In growing female rats, estrogen was growth limiting at appendicular sites; deficiency resulted in a GH-dependent increase in appendicular size, relatively reduced accrual, and so, reduced volumetric BMD in a bigger bone. At the spine, accrual was reduced while growth in size was normal, thus volumetric BMD was reduced in the normal sized bone. Understanding the pathogenesis of low volumetric BMD requires the study of the differing relative growth in size and mass of the axial and appendicular skeleton in the male and female and the regulators of the growth of these traits.     

Discordance in DXA male reference ranges.

Previous studies have reported discordance in female lumbar spine and proximal femur dual-energy X-ray absorptiometry (DXA) reference ranges. Although the NHANES III reference range is recommended for the proximal femur in males and females, there are no published data in men on the concordance or otherwise of the different manufacturer-specific lumbar spine bone mineral density (BMD) reference ranges. Potentially, the use of different reference populations by different manufacturers could result in inconsistencies in the diagnosis of osteopenia or osteoporosis. We compared lumbar spine BMD, as well as T-scores and Z-scores, in 45 men scanned using Lunar DPXL and Norland Excel densitometers. The BMD measured by the two instruments was highly correlated (lumbar spine: r = 0.99, p < 0.0001). However, the two instruments assigned significantly different BMD T-scores. These differences relate primarily to the different standard deviations employed in the calculations. There were also significant differences when BMD was expressed with respect to age-matched values (Z-scores). This study shows that in men, as previously demonstrated in women, two commonly used DXA instruments provide comparable lumbar spine standardized BMD, but there are significant differences in derived T-scores because of differences in the manufacturer-specific reference ranges. Standardization of lumbar spine reference ranges in men should be a high priority.     

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.     

Relationships between the insulin-like growth factor I (IGF-I) receptor gene G3174A polymorphism, serum IGF-I levels, and bone mineral density in postmenopausal Korean women

We investigated the relationships between the IGF-I receptor gene G3174A polymorphism, serum IGF-I levels, and bone mineral density (BMD) in postmenopausal Korean women. The IGF-I receptor gene G3174A polymorphism was analyzed in 367 postmenopausal Korean women. Serum levels of IGF-I, bone turnover markers (osteocalcin, bone alkaline phosphatase, carboxy-terminal cross-linking telopeptide of type I collagen), and BMD at the lumbar spine and proximal femur were measured. The frequencies of the AA, GA, and GG genotypes were 10.9%, 44.1%, and 45.0%, respectively. BMD at the lumbar spine was significantly higher for the AA genotype than the other genotypes and showed an A allelic dose effect; however, no significant differences in BMD were observed at the proximal femur with respect to genotype. No differences were noted between the three genotypes in terms of serum levels of IGF-I or bone turnover markers. Women with low BMD showed a lower prevalence of the AA genotype and A allele than age-matched women with normal BMD. Women with the AA genotype were found to have about half the risk of a low BMD than women with other genotypes. In conclusion, IGF-I receptor gene G3174A polymorphism is associated with lumbar spine BMD in postmenopausal Korean women.     

不同性别的高龄老人每年骨密度变化的比较分析

目的 比较不同性别高龄老人每年骨密度（BMD)变化情况。方法 对1006例高龄老人（男843例、女163例）进行股骨近端和腰椎正位BMD测定,并在12个月后再次进行BMD测定,计算?BMD。然后比较不同性别高龄老人在初次BMD和?BMD上的差异。结果 高龄男性股骨近端和腰椎正位的初次BMD都高于高龄女性（P<0.001),但是不同性别高龄老人在?BMD上的差异无统计学意义（P >0.05);高龄老人股骨近端（除女性大粗隆外）BMD下降,而腰椎正位BMD上升。结论 不同性别高龄老人每年BMD的变化相似,其中股骨近端BMD呈逐年下降趋势,而腰椎正位呈逐年上升趋势。