A Pilot Study of Body Composition and Bone Mineral Density in Healthy Men From Argentina

A precise assessment of bone mineral density (BMD) and body composition can be performed using dual-energy X-ray absorptiometry (DXA). Values of body composition for males would be useful to evaluate the occurrence of alterations in body composition in a number of diseases. The objectives of this study were to establish BMD and body composition values in healthy men and to analyze age-related changes. BMD and body composition of total body and subareas were determined in 116 healthy men (aged 20–79 yr) using DXA. Comparison between 20–29- and 70–79-yr-old men showed that older subjects were shorter (p < 0.03), and had a higher body mass index (p < 0.01). Fat mass increased (+46.7%; p < 0.001) especially in the trunk. Lean mass (LM) decreased (−9.4%; p < 0.05) mainly in the arms and legs. Bone mineral content (BMC) and BMD decreased (−15.3% [p < 0.001], −6.3% [p < 0.05], respectively). Correlation was observed between BMC and LM (r = 0.7, p < 0.01). Values of BMD and body composition in healthy men were obtained. A relation was observed between bone mass and body composition, suggesting that the age-related decrease in LM may be associated to bone mass loss. Further studies should be conducted to elucidate the role of body composition in the occurrence of osteoporosis in men.     

Impact of HIV Infection on Total Body Composition in Treatment—Naive Men Evaluated by Dual-Energy X-ray Absorptiometry Comparison of 90 Untreated HIV-Infected Men to 241 Controls

The aim of this study was to establish the contribution of human immunodeficiency virus (HIV) itself on body composition changes evaluated by dual-energy X-ray absorptiometry (DXA). Body composition evaluated by DXA in 90 HIV never treated men, without comorbidity, or current or past opportunistic infections were compared with 241 healthy volunteers. The mean duration of seropositivity from HIV diagnosis was 41 ± 62 mo, mean CD4 and viral load at the time of DXA were 402/mm³ ± 263 (control values 500–1200/mm³) and 4.2 log copies/mL ± 1.3. Mean age (41 vs 39 yr, respectively, for HIV never treated patients and controls) and mean height (174.5 vs 176 cm) were not different, but mean weight was lower among HIV never treated patients (69.8 vs 78.7 kg). Mean total body bone mineral density (BMD) of naive HIV-infected patients was lower than that of controls (1.20 vs 1.23 g/cm², p = 0.01) but not after adjustment on age, height, lean mass (LM), and fat mass ratio (FMR = % trunk fat mass/% lower limb fat mass). Fat mass (13.2 vs 16.5 kg, p < 0.0001) and LM (53.5 vs 59 kg, p < 0.0001) of naive HIV-infected patients were lower whatever the adjustment variables. The FMR was lower in naive HIV-infected men (1.0 vs 1.3, p < 0.0001) because of a decreased trunk fat mass. After adjustment on age, height, LM, and fat mass, the lower limbs fat mass percentage was higher in HIV-infected men. The profile of naïve HIV-infected patients displayed low lean and fat masses, and a fat mass repartition characterized by a predominant loss in the trunk. Those alterations may result from the catabolic effect of the chronic HIV infection.     

Parathyroid hormone is predictive of low bone mass in Canadian Aboriginal and White women

Canadian Aboriginal women have lower age- and weight-corrected bone mineral density (BMD) and lower vitamin D status than White women. This study was undertaken to describe the differences in biomarkers of bone metabolism and vitamin D in Aboriginal and non-Aboriginal women and to establish which biomarkers were predictive of BMD. In total, 41 rural Aboriginal, 212 urban Aboriginal and 182 urban White women were studied for BMD of the distal radius, calcaneus, lumbar spine, femoral neck, total hip and whole body using dual-energy X-ray absorptiometry. Serum biomarkers measured included calcium, phosphate, alkaline phosphatase (ALP), C-telopeptide of type 1 collagen (CTX), osteocalcin (OC), osteoprotegerin (OPG), parathyroid hormone (PTH) and 25(OH)D. Data were analyzed for differences among the three groups stratified by age (25 to 39, 40 to 59 and 60 to 75 y) using factorial ANOVA. Predictors of BMD including ethnicity, age and body weight were identified using step-wise regression. Unadjusted BMD of all sites declined with age regardless of ethnic grouping. Prediction models for 5 of 6 BMD sites included PTH accounting for age and body weight. Other predictors of BMD included OC for the radius and calcaneus; OPG for spine and total hip; and ALP for whole body and calcaneus. Serum 25(OH)D was not included in any model of BMD. After accounting for all variables in the regression equation, an average Aboriginal woman of 46 y and 79 kg was predicted to have 6% lower calcaneus BMD and 3% lower radius BMD compared to a White woman of the same age and weight. In conclusion, PTH is a better predictor of BMD than 25(OH)D in this population of Aboriginal and White women.     

Peak Bone Density in Croatian Women: Variations at Different Skeletal Sites

It is known that different skeletal sites have different peak bone mass at different times and lose bone at different rates. The purpose of the study was to assess bone mineral density (BMD) in healthy female student population (N = 220), aged 18–25 yr and to analyze whether young women of that age have already started to lose the bone mass at the trabecular and cortical parts of skeleton. The influence of dietary intake and physical activity on their bone mass was also assessed. BMD was measured, using dual-energy X-ray absorptiometry technique, in spine, proximal femur, and distal third of the radius and in total body. Significant negative correlation between age and bone mass was found in all skeletal regions (p < 0.05 spine; p < 0.0001 total femur; and p < 0.01 total body) except in cortical part of the radius. Peak bone mass in young Croatian women was achieved before the age of 20, but later in the long-bone cortical skeleton, where BMD continued to increase after mid-20s. The BMD values are comparable with those from National Health and Nutrition Examination Survey study, except for the cortical part of the radius, where it is significantly lower. Body weight and physical activity were the most significant positive predictors of bone density in all measured sites.     

Effect of Ascites on Bone Density Measurement in Cirrhosis

Cirrhosis is an independent risk factor for the development of osteoporosis. The presence of ascites in patients with cirrhosis may affect the accuracy of bone density measurement in the spine. Twenty cirrhotic patients had bone mineral density (BMD) measurements of the lumbar spine, femoral neck, hip, and total body using dual-energy X-ray absorptiometry (DXA; Lunar Prodigy) before and after large-volume paracentesis. To establish short-term precision of DXA measurement, 28 healthy adults also had duplicate BMD measurements on the same day. After paracentesis (6.4 ± 2.0 L), there was a significant increase in the spine BMD of 4.2% (p = 0.003) and in the total hip BMD of 1.3% (p = 0.002), but there was no change in the femoral neck or total body. No significant differences (p > 0.1) were seen in duplicate BMD measurements at any site among the healthy cohort. Within-patient changes in spine (p = 0.001) and total hip (p = 0.001) BMD measurements were significantly greater in patients with ascites than in the healthy cohort. These changes in BMD measurements were not associated with age, gender, amount of fluid removed, or time interval between measurements. These results suggest that ascites cause a fluid artifact in the soft tissue and bone interface that can falsely lower BMD measurements, particularly in the spine.     

Relative contribution of body composition to bone mineral density at different sites in men and women of South Korea

We examined the relative contribution of body composition to bone mineral density (BMD) at various sites in 1406 Korean rural men and women, aged 19–80 years, from July to August 2004. The BMD was measured at peripheral (distal forearm and calcaneus) and central (lumbar spine at L1–L4, femoral neck, trochanter, and Ward's triangle) using dual-energy X-ray absorptiometry. In multivariate analyses, the linear regression models were adjusted for relevant covariates. In premenopausal women, only lean mass had a significant positive correlation with BMD at all sites. In postmenopausal women, fat mass was significantly positively correlated with BMD at all sites, except the Ward's triangle; fat mass was the only determinant of BMD at the lumbar, distal forearm, and calcaneus sites, whereas both lean and fat mass contributed to BMD at the hip, with the effect of lean mass being slightly greater than that of fat mass. In younger men, lean mass had a significant positive contribution to BMD at all sites, whereas fat mass appeared to contribute negatively to BMD at all sites, except the calcaneus. In older men, lean mass made a significant positive contribution to the BMD at all sites; fat mass also made a significant positive contribution to the BMD at the forearm and calcaneus. These data indicate that in the Korean rural population, lean mass may be an important determinant of the BMD, whereas fat mass may contribute positively to BMD only in postmenopausal women and older men.     

Increased bone mineral density in Aboriginal and Torres Strait Islander Australians: impact of body composition differences

Bone mineral density (BMD) has been reported to be both higher and lower in Indigenous women from different populations. Body composition data have been reported for Indigenous Australians, but there are few published BMD data in this population. We assessed BMD in 161 Indigenous Australians, identified as Aboriginal (n=70), Torres Strait Islander (n=68) or both (n=23). BMD measurements were made on Norland-XR46 (n=107) and Hologic (n=90) dual-energy X-ray absorptiometry (DXA) machines. Norland BMD and body composition measurements in these individuals, and also in 36 Caucasian Australians, were converted to equivalent Hologic BMD (BMD(H)) and body composition measurements for comparison. Femoral neck (FN) and lumbar spine Z-scores were high in Indigenous participants (mean FN Z-score: Indigenous men +0.98, p<0.0001 vs. mean zero; Indigenous women +0.82, p<0.0001 vs. mean zero). FN BMD(H) was higher in Aboriginal and/or Torres Strait Islander than Caucasian participants, after adjusting for age, gender, diabetes and height and remained higher in men after addition of lean mass to the model. We conclude that FN BMD is higher in Aboriginal and/or Torres Strait Islander Australians than Caucasian Australian reference ranges and these differences still remained significant in men after adjustment for lean mass. It remains to be seen whether these BMD differences translate to differences in fracture rates.     

Characteristics of regional bone mineral density and soft tissue composition in patients with atraumatic vertebral fractures

To clarify the characteristics of total body and regional bone mineral density (BMD) and soft tissue composition in patients with atraumatic vertebral fractures (AVF), we measured total body and regional BMD, lean mass, and fat mass using dual-energy X-ray absorptiometry. Sixty-four women, aged 55–75 years, were divided into two groups: women with AVF (fracture group, n = 30) and women without AVF (nonfracture group, n = 34). Mean BMD of the second to fourth lumbar vertebrae (L2–4BMD), regional BMD, and soft tissue mass were measured. Regional BMD was measured in the head, arms, legs, ribs, thoracic vertebrae, lumbar vertebrae, and pelvis. Lean mass and fat mass of head, arms, legs, and trunk were measured. L2–4BMD, total body BMD, and BMD of the lumbar spine, thoracic spine, and pelvis of the fracture group were significantly lower than those of the nonfracture group (P < 0.001). Total lean and fat mass of the fracture group tended to be lower than that of the nonfracture group. The results suggest that BMD of weight-bearing bones, except for that of the bones of the legs of the fracture group, is significantly lower than that of the nonfracture group, and that total body lean and fat mass may be a predictor for AVF. Received: September 27, 1999 / Accepted: January 7, 2000     

Changing femoral geometry in growing girls: A cross-sectional DEXA study

In elderly women, a long hip axis length has been shown to increase the risk of hip fracture. However, to date, few measurements of hip geometry have been reported in children and adolescents. The present cross-sectional dual-energy X-ray absorptiometry (DEXA) study of 200 girls aged 3–16 years was undertaken to determine at what age adult hip geometry is achieved and to examine possible influences of anthropometry and body composition on the development of femur axis length (FAL) and femur width (FW) during growth. Adult values for FAL and FW were achieved by age 15 years. Age, height, lean tissue mass, total body bone mineral content (BMC), weight, FW, neck of femur bone mineral density (BMD), and fat were each strongly associated with FAL (p < 0.001), the highest correlations being with age (r = 0.917) and height (r = 0.906). However, after adjusting for age and height, only lean tissue mass, weight, and fat mass remained significantly associated with FAL, suggesting that bone mineral accrual does not influence variance in FAL. Our results also suggested that fat mass and weight per se tended to have greater influence on FW than on FAL in age- and height-adjusted data. Twin studies indicate that 20% of adult hip axis length is associated with environmental factors. We therefore conclude that any environmental effects of physical activity or nutrition on hip geometry must occur before early teen-age years.     

Genetic background influences fluoride's effects on osteoclastogenesis

Excessive fluoride (F) can lead to abnormal bone biology. Numerous studies have focused on the anabolic action of F yet little is known regarding any action on osteoclastogenesis. Little is known regarding the influence of an individual's genetic background on the responses of bone cells to F. Four-week old C57BL/6J (B6) and C3H/HeJ (C3H) female mice were treated with NaF in the drinking water (0 ppm, 50 ppm and 100 ppm F ion) for 3 weeks. Bone marrow cells were harvested for osteoclastogenesis and hematopoietic colony-forming cell assays. Sera were analyzed for biochemical and bone markers. Femurs, tibiae, and lumbar vertebrae were subjected to microCT analysis. Tibiae and femurs were subjected to histology and biomechanical testing, respectively. The results demonstrated new actions of F on osteoclastogenesis and hematopoietic cell differentiation. Strain-specific responses were observed. The anabolic action of F was favored in B6 mice exhibiting dose-dependent increases in serum ALP activity (p < 0.001); in proximal tibia trabecular and vertebral BMD (tibia at 50&100 ppm, p = 0.001; vertebrae at 50 and 100 ppm, p = 0.023&0.019, respectively); and decrease in intact PTH and sRANKL (p = 0.045 and p < 0.001, respectively). F treatment in B6 mice also resulted in increased numbers of CFU-GEMM colonies (p = 0.025). Strain-specific accumulations in bone [F] were observed. For C3H mice, dose-dependent increases were observed in osteoclast potential (p < 0.001), in situ trabecular osteoclast number (p = 0.007), hematopoietic colony forming units (CFU-GEMM: p < 0.001, CFU-GM: p = 0.006, CFU-M: p < 0.001), and serum markers for osteoclastogenesis (intact PTH: p = 0.004, RANKL: p = 0.022, TRAP5b: p < 0.001). A concordant decrease in serum OPG (p = 0.005) was also observed. Fluoride treatment had no significant effects on bone morphology, BMD, and serum PYD cross-links in C3H suggesting a lack of significant bone resorption. Mechanical properties were also unaltered in C3H. In conclusion, short term F treatment at physiological levels has strain-specific effects in mice. The expected anabolic effects were observed in B6 and novel actions hallmarked by enhanced osteoclastogenesis shifts in hematopoietic cell differentiation in the C3H strain.     

Diabetes is associated independently of body composition with BMD and bone volume in older white and black men and women: The Health, Aging, and Body Composition Study.

The association between type 2 diabetes, BMD, and bone volume was examined to determine the effect of lean and fat mass and fasting insulin in the Health, Aging, and Body Composition Study, which included white and black well-functioning men and women 70-79 years of age (N = 2979). Diabetes predicted higher hip, whole body, and volumetric spine BMD, and lower spine bone volume, independent of body composition and fasting insulin. INTRODUCTION: The purpose of this study was to determine if the association between type 2 diabetes and higher BMD observed in older white women is seen in elderly white men and blacks and to evaluate if higher BMD in diabetic individuals is accounted for by lean mass, fat mass, or fasting insulin differences. MATERIALS AND METHODS: In the Health, Aging, and Body Composition Study, which included white and black well-functioning men and women 70-79 years of age (N = 2979), 19% of participants had diabetes at baseline. Of those with diabetes, 57% were men, and 62% were black. Multivariate linear regression models examined independent effects of diabetes, lean mass, fat mass, visceral fat, and fasting insulin on BMD and bone volume while adjusting for relevant covariates. RESULTS AND CONCLUSIONS: Fasting insulin, visceral fat, and volumetric spine BMD, assessed by CT, and lean mass, fat mass, and total hip and whole body BMD, assessed by DXA, were higher (p < or = 0.05 for all) for those with diabetes. Hip BMD was higher in white men (0.99 +/- 0.14 versus 0.93 +/- 0.14 g/cm2, p < 0.001), black men (1.06 +/- 0.17 versus 1.00 +/- 0.15 g/cm2, p < 0.001), white women (0.83 +/- 0.13 versus 0.76 +/- 0.13 g/cm2, p < 0.001), and black women (0.90 +/- 0.15 versus 0.85 +/- 0.15 g/cm2, p < 0.001) with diabetes compared with those without diabetes, although the relationship was attenuated by body composition. In multiple regression models, diabetes was an independent predictor of higher hip, whole body, and volumetric spine BMD in all participants (p < or = 0.001), but lower spine volume (p = 0.01) and higher hip BMD for each race-gender group (p < or = 0.01). Type 2 diabetes was associated with a 4-5% higher total hip BMD in all race-gender groups of elderly adults, independent of body composition and fasting insulin levels.     

Assessment of Spine Bone Mineral Density in Juvenile Idiopathic Arthritis: Impact of Scan Projection

Although children with juvenile idiopathic arthritis (JIA) are at risk for vertebral fractures, recent conventional posterior-anterior (PA) spine dual-energy X-ray absorptiometry studies reported minimal areal bone mineral density (aBMD, g/cm²) deficits. Width-adjusted BMD (WA-BMD, g/cm³) represents the bone mineral content (BMC) from the lateral projection, excluding the dense cortical spinous processes, divided by the estimated vertebral body volume based on paired PA-lateral bone dimensions. Therefore, WA-BMD may be more sensitive to JIA effects on the predominantly trabecular vertebral body. Age- and sex-specific Z-scores for spine aBMD and WA-BMD were generated in 84 JIA subjects compared with healthy controls, aged 5–21 yr. JIA was associated with lower mean WA-BMD Z-scores (−0.78, 95% CI: −1.03, −0.53; p < 0.001) and aBMD Z-scores (−0.26, 95% CI: −0.49, −0.02; p < 0.05), compared with controls. WA-BMD Z-scores were significantly lower than aBMD Z-scores in JIA (p < 0.001). A significant JIA by age interaction (p < 0.001) indicated that the magnitude of the difference between WA-BMD and aBMD Z-scores was greater in younger subjects. In conclusion, WA-BMD may be more sensitive to disease effects in children because it selectively measures the trabecular-rich vertebral body and is independent of growth-related changes in BMC of the dense spinous processes.     

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.     

Determinants of Changes in Bone Density: A 5-Year Follow-Up Study of Adult Male Monozygotic Twins

The relative importance of determinants in bone mineral density (BMD) in adult men is partly unclear. Our goals were to investigate the effects of familial aggregation and behavioral factors on the change in BMD during a 5-yr follow-up. Subjects (n = 140) were 70 exposure-discordant monozygotic twin pairs (age 35–69 yr). BMD was measured with the same dual-energy X-ray absorptiometry scanner at baseline and at the 5-yr follow-up. A variety of covariates were used including physical examination and interview data. Multivariate linear regression was used. The mean annual decrease in femoral BMD was 0.2%. The mean lumbar BMD was unchanged, although 8–17% of subjects had a decrease of more than 5%. Familial aggregation explained 14% of the changes in femoral BMD and 19% in lumbar BMD. The stability of BMD in the follow-up was high, both for individuals (intraclass correlation coefficient [ICC] = 0.90–0.94) and for co-twins in a pair (ICC = 0.77–0.84). In femoral BMD, use of alcohol (p = 0.006), coffee (p = 0.046), and beta-blockers (p = 0.043) led to increases, whereas smoking led to a decrease (p < 0.01). We concluded that frequent increases in BMD, influenced by beta-blockers, partly explain the minor mean changes during follow-up; however, about every 10th subject had a significant decrease. Overall, familial effects played a dominant role in BMD changes in adult men.     

Hyperinsulinemia and bone mineral density in an elderly population: The Rotterdam study

We studied the association between insulin and glucose levels and bone mineral density (BMD) in a population based study of 5931 elderly men and women. Serum insulin was measured 2 h after a nonfasting oral glucose load in subjects not using antidiabetes medication. BMD was measured by dual-energy X-ray absorptiometry in the lumbar spine and the proximal femur. In addition, the participants were asked about fractures in the preceding 5 years. Higher bone mass was associated with higher glucose and postload insulin levels at all sites, as well as with increased waist/Ahip ratio and body mass index. In men, the mean age-adjusted BMD at the lumbar spine (in mg/cm²) increased 4.64 per mmol/L serum glucose (95% CI 1.46–7.82) and 0.35 per mU/L postload insulin (0.17–0.53). In women, these values were 6.88 (4.37–9.39) for glucose and 0.25 (0.11–0.39) for insulin (for all analyses: p < 0.01). The relations were essentially the same with BMD measured in the femur, as well as after adjustment for waist/hip ratio. After adjustment for body mass index, the associations were reduced and lost statistical significance in women. After excluding subjects with diabetes mellitus, the results remained the same. Subjects with a history of nonvertebral fractures had a lower BMD and lower postload insulin levels than those without. The difference in insulin levels was statistically significant in men only (12.5 mU/L, p < 0.001). Excluding men with diabetes mellitus or further adjustment for waist/hip ratio, body mass index or BMD did not change this difference. These results suggest that increased insulin levels are associated with an increased BMD and might be related to a lower fracture rate.     

Bone density and bone area in Canadian Aboriginal women: the First Nations Bone Health Study

INTRODUCTION: Canadian Aboriginal women are at increased risk of fracture compared with the general population. HYPOTHESIS: There is disproportionately reduced bone density in Aboriginal women as compared to white females of similar age. METHODS: A random age-stratified (25-39, 40-59 and 60-75) sample of Aboriginal women (n=258) and white women (n=181) was recruited. All subjects had calcaneus and distal forearm bone density measurements, and urban participants (n=397 [90.4%]) also had measurements of the lumbar spine, hip and total body. RESULTS: Unadjusted measurements were similar in the two groups apart from the distal forearm which showed a significantly lower mean Z-score in the Aboriginal women (p=0.03). Aboriginal women were heavier than white women (81.0+/-18.0 kg vs. 76.0+/-18.0 kg, p=0.02). Weight was directly associated with BMD at all measurement sites (p<0.00001) and potentially confounded the assessment of ethnicity on bone mass measurements. Weight-adjusted ANCOVA models demonstrated significantly lower bone density in Aboriginal than white women for the calcaneus, distal forearm, and total body (all p<0.05), but not at the other sites. ANCOVA models (adjusted for age, height and weight) were used to explore differences in bone area and bone mineral content (BMC). There was a significant effect of ethnicity on bone area with Aboriginal women having larger adjusted mean values than white women (lumbar spine p=0.038, total hip p=0.0004, total body p=0.020). In contrast, there was no detectable effect of ethnicity on BMC (all p>0.2). CONCLUSIONS: We identified significant site-specific differences in age-and weight-adjusted bone density for Aboriginal and white women. Larger bone area, rather than a reduction in BMC, appeared to be primarily responsible. Further work is needed to define how these differences in bone density and geometry affect indices of bone strength.     

Volumetric bone density of the lumbar spine is related to fat mass but not lean mass in normal postmenopausal women

We have previously found that fat mass but not lean body mass is related to bone mineral density (BMD) in women. In these and most other studies of the dependence of BMD on body composition, areal rather than volumetric bone density was measured. It is possible that the dependence of this variable on body size introduced a scale artifact that contributed to the previous findings. The present study addresses this issue by measuring thevolumetric density of the third lumbar vertebra from simultaneous anteroposterior (AP) and lateral scans using dual-energy X-ray absorptiometry in 119 normal postmenopausal women. Whole body fat and lean body mass were also measured using this technique. In the AP projection, BMD was similarly related to body weight and to fat mass (r=0.44,p<0.0001 for both) but not to lean body mass (r=0.17, NS). BMD in the lateral projection was less closely related to body composition than was AP BMD, but the greater impact of fat (r=0.25,p<0.01) than lean body mass (r=0.09, NS) was still evident. When AP or lateral BMDs were divided by height, arm span or the square root of the scan area to produce an index with the dimensions of volumetric density, the dependence of BMD on body weight and fat mass were not affected but the relationship to lean body mass was eliminated (–0.02<r<0.09). Similarly, the volumetric density of the third lumbar vertebra was related to fat mass (r=0.21,p=0.02) but not to lean body mass (r=0.01). It is concluded that BMD is related to fat mass and that previously reported associations between lean body mass and BMD are probably contributed to by a scaling factor arising from failure to measure volumetric bone density.     

Lean mass as a significant determinant of regional and total body bone mineral density in premenopausal women

We investigated the relations of body composition to regional and total body bone mineral density (BMD) in 275 healthy Japanese premenopausal women (mean age, 37.1 ± 9.2 years; range, 16–55 years). In all subjects, the right side was dominant. BMD of the head, bilateral arms, lumbar spine (L2–L4), bilateral legs, and total body were measured using whole-body scanning by dual-energy X-ray absorptiometry (DXA). Total fat mass, total lean mass, regional lean mass, and regional fat mass were measured by DXA. Baseline characteristics including age, height, body weight, and body mass index were recorded for each subject. Possible correlations between regional or total body BMD with variables were determined on univariate and stepwise multiple regression analysis. BMD, lean mass, and fat mass were compared between the bilateral extremities. Total lean mass for the right arm, regional lean mass for the left arm, total lean mass for the lumbar spine, body weight for the bilateral legs, and total lean mass for the whole body were the most significant determinants of BMD on stepwise multiple regression analysis. Right-arm BMD was significantly higher than left-arm BMD. However, no significant difference was observed between BMD in the right and left legs. We concluded that lean mass is a more significant determinant of regional and total body BMD than fat mass in premenopausal women. Received: June 12, 1997 / Accepted: Oct. 23, 1997