Effect of dietary protein on bone loss in elderly men and women: the Framingham Osteoporosis Study.

Few studies have evaluated protein intake and bone loss in elders. Excess protein may be associated with negative calcium balance, whereas low protein intake has been associated with fracture. We examined the relation between baseline dietary protein and subsequent 4-year change in bone mineral density (BMD) for 391 women and 224 men from the population-based Framingham Osteoporosis Study. BMD (g/cm2) was assessed in 1988-1989 and in 1992-1993 at the femur, spine, and radius. Usual dietary protein intake was determined using a semiquantitative food frequency questionnaire (FFQ) and expressed as percent of energy from protein intake. BMD loss over 4 years was regressed on percent protein intake, simultaneously adjusting for other baseline factors: age, weight, height, weight change, total energy intake, smoking, alcohol intake, caffeine, physical activity, calcium intake, and, for women, current estrogen use. Effects of animal protein on bone loss also were examined. Mean age at baseline (+/-SD) of 615 participants was 75 years (+/-4.4; range, 68-91 years). Mean protein intake was 68 g/day (+/-24.0; range, 14-175 g/day), and mean percent of energy from protein was 16% (+/-3.4; range, 7-30%). Proportional protein intakes were similar for men and women. Lower protein intake was significantly related to bone loss at femoral and spine sites (p < or = 0.04) with effects similar to 10 lb of weight. Persons in the lowest quartile of protein intake showed the greatest bone loss. Similar to the overall protein effect, lower percent animal protein also was significantly related to bone loss at femoral and spine BMD sites (all p < 0.01) but not the radial shaft (p = 0.23). Even after controlling for known confounders including weight loss, women and men with relatively lower protein intake had increased bone loss, suggesting that protein intake is important in maintaining bone or minimizing bone loss in elderly persons. Further, higher intake of animal protein does not appear to affect the skeleton adversely in this elderly population.     

Risk factors for longitudinal bone loss in elderly men and women: the Framingham Osteoporosis Study.

Few studies have evaluated risk factors for bone loss in elderly women and men. Thus, we examined risk factors for 4-year longitudinal change in bone mineral density (BMD) at the hip, radius, and spine in elders. Eight hundred elderly women and men from the population-based Framingham Osteoporosis Study had BMD assessed in 1988-1989 and again in 1992-1993. BMD was measured at femoral neck, trochanter, Ward's area, radial shaft, ultradistal radius, and lumbar spine using Lunar densitometers. We examined the relation of the following factors at baseline to percent BMD loss: age, weight, change in weight, height, smoking, caffeine, alcohol use, physical activity, serum 25-OH vitamin D, calcium intake, and current estrogen replacement in women. Multivariate regression analyses were conducted with simultaneous adjustment for all variables. Mean age at baseline was 74 years +/-4.5 years (range, 67-90 years). Average 4-year BMD loss for women (range, 3.4-4.8%) was greater than the loss for men (range, 0.2-3.6%) at all sites; however, BMD fell with age in both elderly women and elderly men. For women, lower baseline weight, weight loss in interim, and greater alcohol use were associated with BMD loss. Women who gained weight during the interim gained BMD or had little change in BMD. For women, current estrogen users had less bone loss than nonusers; at the femoral neck, nonusers lost up to 2.7% more BMD. For men, lower baseline weight and weight loss also were associated with BMD loss. Men who smoked cigarettes at baseline lost more BMD at the trochanter site. Surprisingly, bone loss was not affected by caffeine, physical activity, serum 25-OH vitamin D, or calcium intake. Risk factors consistently associated with bone loss in elders include female sex, thinness, and weight loss, while weight gain appears to protect against bone loss for both men and women. This population-based study suggests that current estrogen use may help to maintain bone in women, whereas current smoking was associated with bone loss in men. Even in the elderly years, potentially modifiable risk factors, such as weight, estrogen use, and cigarette smoking are important components of bone health.     

Depression and bone mineral density in a community sample of men: Geelong Osteoporosis Study

Background

Previous research in psychiatric and community samples has demonstrated reduced bone mineral density (BMD) in individuals with both clinical depression and depressive symptoms, although the findings are equivocal. This study aimed to investigate the association between self-reported depression and BMD in a community sample of men aged 20-96 years enrolled in the Geelong Osteoporosis Study.

Methods

A self-report questionnaire based on DSM-IV criteria was used to determine lifetime prevalence rates of depression within the study sample at baseline. Those currently taking oral glucocorticoids, testosterone or bisphosphonates were excluded from the analysis (n = 23) resulting in a sample of 1279 men.

Results

In this sample, 155 men reported a lifetime history of depression (LHX). There were no differences in age, weight, height, calcium intake, smoking rates or unadjusted BMD at the femoral neck between the cases and the controls, whereas unadjusted BMD at the spine was significantly lower in those with a LHX (1.254 ± 0.187 vs 1.293 ± 0.194 g/cm²). BMD adjusted for age, weight, calcium intake and smoking was 3.6% lower at the spine (1.255 ± 0.016 vs 1.295 ± 0.006 g/cm²) and 3.4% lower at the femoral neck (0.973 ± 0.011 vs 1.007 ± 0.004 g/cm²) in those with a LHX compared to controls.

Conclusion

These data are consistent with previous findings of diminished BMD in people with depressive disorders and symptoms and suggest that depression may be a risk factor for reduced BMD in community-dwelling adult men.     

Application of the National Osteoporosis Foundation Guidelines to postmenopausal women and men: the Framingham Osteoporosis Study

Summary  

We applied the 2008 National Osteoporosis Foundation (NOF) Guidelines to Framingham Osteoporosis Study participants and found nearly one half of Caucasian postmenopausal women and one sixth of men aged 50 years and older would be recommended for osteoporosis treatment. Given the high proportion of persons recommended for treatment, NOF Guidelines may need to be re-evaluated with respect to budget impact.     

Osteoporosis in men and women: a story about bone mineral density thresholds and hip fracture risk.

In postmenopausal women, the T score for bone mineral density (BMD) is a well-accepted diagnostic criterion for osteoporosis. It is also used to assess fracture risk. However, it is unclear whether in elderly men similar BMD thresholds should be used. Different hypotheses have been proposed for the relation of BMD with hip fracture risk in men. In this study, we tested those hypotheses using a mathematical model and we compared the calculated results with observed prospective data from the Rotterdam study. In the model, we combined the observed femoral neck BMD distribution for men and women with previously derived hip fracture risk functions based on age and BMD. For men, we tested different hypotheses for the relation of BMD with hip fracture risk. The relation of BMD with hip fracture risk is similar in men and women (scenario 1) or the relative risk (RR) per standard deviation (SD) decrease of BMD is either larger or smaller in men than in women (scenario 2a and 2b), or, at a similar absolute fracture risk, men have a higher BMD (scenario 3). In the prospective data, men with a hip fracture had an average BMD that was 0.070 g/cm2 higher than women with a hip fracture. The calculated results from the first scenario were consistent with those data and were also consistent with the observed hip fracture incidence and the observed female-to-male (F/M) risk ratio (1.7). When the RR for each SD decrease of BMD was assumed to be either larger or smaller in men than in women (second scenario), the calculated average BMD difference in men and women became respectively smaller or larger than observed. When men would have a higher fracture risk at similar BMD levels (third scenario), the calculated total number of hip fractures increased and even exceeded that in women, with an F/M risk ratio of 0.94 in our example. In women, a larger proportion of hip fractures occurs at a T score below -2.5 than in men using the same absolute BMD threshold, but using a male-specific T score largely solves this diagnostic problem. Taken together, the average hip fracture risk in men is much lower than in women but appeared to be similar at the same BMD. Therefore, we propose the use of the same absolute BMD thresholds for decisions about interventions.     

Aging bone in men and women: beyond changes in bone mineral density

Using peripheral quantitative computed tomography (pQCT) we assessed trabecular and cortical bone density, mass and geometric distribution at the tibia level in 512 men and 693 women, age range 20–102 years, randomly selected from the population living in the Chianti area, Tuscany, Italy. Total, trabecular and cortical bone density decreased linearly with age (p<0.0001 in both sexes), and the slope of age-associated decline was steeper in women than in men. In men, the cortical bone area was similar in different age groups, while in women older than 60 years it was significantly smaller by approximately 1% per year. The total cross-sectional area of the bone became progressively wider with age, but the magnitude of the age-associated increment was significantly higher in men than in women (p<0.001). The minimum moment of inertia, an index of mechanical resistance to bending, remained stable with age in men, while it was significantly lower in older compared with younger women (0.5% per year). The increase in bone cross-sectional area in aging men may contribute to the maintenance of adequate bone mechanical competence in the face of declining bone density. In women this compensatory mechanism appears to be less efficient and, accordingly, the bone mechanical competence declines with age. The geometric adaptation of increasing cross-sectional bone size is an important component in the assessment of bone mechanical resistance which is completely overlooked, and potentially misinterpreted, by traditional planar densitometry.     

Bone mineral density in elderly men and women: results from the Framingham osteoporosis study.

Our study investigated bone mineral density of the proximal femur and ultradistal and proximal radius in a population of elderly men and women. The Framingham study started in 1948, following a population-based sample for evaluation of cardiovascular risk factors and events. During the 20th biennial Framingham examination (1988-89) we conducted the Framingham osteoporosis study, measuring bone mineral density in the proximal femur and distal and proximal radius for 1154 study participants. Ages ranged from 68 to 98 years, with a mean age of 76 years. Bone mineral density was measured using Lunar SP2 and DP3 densitometers. This cross-sectional study evaluates mean bone mineral density measurements at each site by 5 year age intervals for men and women, testing for trends in bone density with age. Analyses were repeated adjusting for weight and height. Among the 446 and 708 women, bone mineral density of the femur and bone mineral content of the proximal radius were inversely and significantly related to age in both sexes and were considerably higher in men than women at all sites. The linear decline with age group in our cross-sectional study remained after multivariate adjustment for height and weight. The ultradistal radius showed no significant correlation with age for either sex. There were significant correlations between the bone measurements made at different sites for both men and women (range in r = 0.27-0.89). Cross-sectional curves of bone mineral density with age showed no significant differences in slope between males and females.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dietary silicon intake is positively associated with bone mineral density in men and premenopausal women of the Framingham Offspring cohort.

The role of dietary silicon in bone health in humans is not known. In a cross-sectional, population-based study (2847 participants), associations between dietary silicon intake and BMD were investigated. Dietary silicon correlated positively and significantly with BMD at all hip sites in men and premenopausal women, but not in postmenopausal women, suggesting that increased silicon intake is associated with increased cortical BMD in these populations. INTRODUCTION: Osteoporosis is a burgeoning health and economic issue. Agents that promote bone formation are widely sought. Animal and cellular data suggest that the orthosilicate anion (i.e., dietary silicon) is involved in bone formation. The intake of silicon (Si, approximately 30 mg/day) is among the highest for trace elements in humans, but its contribution to bone health is not known. MATERIALS AND METHODS: In a cross-sectional, population-based study, we examined the association between silicon intake and bone mineral density (BMD) in 1251 men and 1596 pre- and postmenopausal women in the Framingham Offspring cohort (age, 30-87 years) at four hip sites and lumbar spine, adjusting for all potential confounding factors known to influence BMD and nutrient intake. RESULTS: Silicon intake correlated positively with adjusted BMD at four hip sites in men and premenopausal women, but not in postmenopausal women. No significant association was observed at the lumbar spine in any group. Categorical analysis by Si intake, or energy-adjusted Si intake, supported these findings, and showed large differences in BMD (up to 10%) between the highest (> 40 mg Si/day) and lowest (< 14 mg Si/day) quintiles of silicon intake. A significant association at the lumbar spine in men was also observed. Further analyses indicated that some of the effects seen for moderate consumption of alcoholic beverages on BMD might be attributed to Si intake. CONCLUSIONS: These findings suggest that higher dietary silicon intake in men and younger women may have salutary effects on skeletal health, especially cortical bone health, that has not been previously recognized. Confirmation of these results is being sought in a longitudinal study and by assessment of the influence of silicon intake on bone markers in this cohort.     

Fracture incidence and association with bone mineral density in elderly men and women: the Rotterdam Study

The incidence of all non-vertebral fractures, as well as the relation to bone mineral density (BMD), was quantified in 7806 men and women from the Rotterdam Study, a prospective, population-based cohort study of men and women aged 55 years and older. In addition, the sensitivity of using a T-score at or below -2.5 for identifying subjects at risk for fractures was assessed. At baseline, between 1990 and 1993, femoral neck BMD was measured by dual energy X-ray absorptiometry (DXA). Subsequently, gender-specific T-scores were calculated using the NHANES reference population. During a mean follow-up of 6.8 years, information on incident non-vertebral fractures was gathered.In general, hip, wrist and upper humerus fractures are the most frequent fractures in both men and women. Femoral neck BMD appears to be an equally important risk factor in both genders, and is especially related to hip fractures. For all non-vertebral fractures, the age-adjusted hazard ratio (95% confidence interval) per standard deviation decrease in femoral neck BMD was 1.5 (1.4-1.6) for women and 1.4 (1.2-1.6) for men. For hip fractures, the hazard ratios were 2.1 (1.7-2.5) for women and 2.3 (1.6-3.3) for men.Only 44% of all non-vertebral fractures occurred in women with a T-score below -2.5; in men, this percentage was even lower (21%). Thus, there is a clear need for the development of more sensitive risk assessment tools, using not only BMD, but also other clinical predictors of fractures.     

Osteoporosis of the spine: correlation between vertebral deformity and bone mineral density in postmenopausal women

The purpose of this study is to evaluate the relation of bone mineral density (BMD) or the age-matched z score and osteoporotic vertebral fractures. The radiographs and spinal bone mineral density of 131 consecutive postmenopausal patients were retrospectively reviewed. The vertebral fractures between T4 and L4 were graded. Sixty-two patients had no fractures, and 69 had 1 or more fractures. In the nonfracture group, the mean age was 62.6 years, BMD was 0.88 g/cm2, and the z score was -1.00. In the fracture group, the mean age was 69.6 years, BMD was 0.788 g/cm2, and the z score was -1.26. Patients with 2 and 3 or more fractures had a lower mean BMD than that of the nonfracture group (P < .01). The z score (adjusted for age) was significantly lower only in patients with 3+ fractures (P < .05). Patients with grade 2 and grade 3 of any fracture type had significantly lower BMD (P < .01). The z score was lower only in those with grade 3 fracture (P < .05). Our study indicates that the clinical use of BMD z score adjusted for age is a better predictor of severity of vertebral fractures than is BMD alone.     

Bone mineral density reference ranges for Australian men: Geelong Osteoporosis Study

Summary  

A large population-based random sample of Australian white men was used to provide normative bone mineral density (BMD) data at multiple anatomical sites. The femoral neck BMD data are very similar to those obtained in USA non-Hispanic white males participating in the National Health and Nutrition Examination Survey III (NHANES III). The reference ranges will be suitable for similar populations.     

男女强直性脊柱炎骨密度对比分析

目的探讨男性和女性强直性脊柱炎(Ankylosing Spondylitis,AS)患者骨密度（Bone mineral density,BMD)及BMD与其 他临床指标的相关性。方法回顾性调查2006年3月至2014年12月中日友好医院中医风湿病科确诊为AS的患者,其中女 性168例,男性587例,年龄在20岁~45岁,双光能X线法检测腰椎、股骨颈、股骨粗隆的BMD,并与年龄、病程、疾病活动性 指标、影像学指标进行相关分析。结果①男性AS患者腰椎BMD较女性腰椎BMD显著减低（P < 0. 01);男性AS患者骨质 疏松（Osteoporosis,OP)及骨量减少（Osteopenia,OT)总发生率为"71. 04%,显著高于女性AS患者的42. 86% ( P < 0. 05),且在 腰椎、股骨颈、股骨粗隆部位的OP、OT发生率均显著高于女性AS患者(P <0. 01);②中年龄组(30 ~ 39岁）及高年龄组(40? 45岁）的AS患者中男性腰椎丽D较女性显著降低（P < 0. 01);高年龄组AS患者中男性股骨颈丽D较女性显著降低（P < 0. 01);病程5 ~ 10年及大于10年的AS患者中男性腰椎、股骨颈丽D较女性显著降低（P <0. 01、P <0. 01、P <0. 01、尸<05)③相关性分析显示男性与女性AS患者BMD与疾病活动指标ESR、CRP,体征、骶髂关节炎分级等有相关性,而男性AS 患者丽D与年龄、病程尚呈显著负相关(P <0. 05)。结论男女AS患者均有较高的OT、OP的发生率,且男性OT及OP的较 之女性更为显著,特别是腰椎BMD男性AS患者减低更为突出。此外年龄越大、病程越长的男性AS患者BMD减低程度越明 显。男性与女性AS患者丽D的下降均与疾病程度、病情的活动性、肢体活动功能、HLA427相关联。对于男性AS患者更需 要重视OT及OP的诊断与防治。     

Nitrate use and changes in bone mineral density: the Canadian Multicentre Osteoporosis Study

Summary  Nitrates may have beneficial effects on bone. To determine if nitrates were associated with increased bone mineral density (BMD), we conducted a secondary analysis using data from subjects in a prospective study. Subjects reporting nitrate use had increased BMD compared with non-users, confirming that nitrates have positive BMD effects in women and men. Introduction  Prior studies suggest positive associations between nitrates and bone. Methods  We used linear regression models, stratified by gender and adjusted for age, weight, and baseline differences, to determine the association between daily nitrate use and BMD among subjects participating in the Canadian Multicentre Osteoporosis Study. All results are reported as annualised percent change in BMD at the hip and spine among nitrate users compared to non-users. Results  We included 1,419 men (71 reported daily nitrate use) and 2,587 women (97 reported daily nitrate use). Male non-users had decreased hip BMD (−1.3%; 95% confidence interval [95%CI] = −1.6 to −1.1) and increased spine BMD (2.8%; 95%CI = 2.5 to 3.1). Male nitrate users had increased hip BMD (1.4%; 95%CI = 0.1 to 2.8) and spine BMD (4.5%; 95%CI = 3.2 to 5.7). Among women, non-users had decreased hip BMD (−1.9; 95%CI = −2.1 to −1.7) and increased spine BMD (2.1%; 95%CI = 1.9 to 2.4) whilst users had an increase in hip BMD (2.0%; 95%CI = 1.2 to 2.8) and spine BMD (4.1%; 95%CI = 3.4 to 4.9). Conclusion  Nitrate use is associated with increased BMD at the hip and spine in men and women.     

Age,gender, and body mass effects on quantitative trait loci for bone mineral density: the Framingham Study

A genome-wide scan was performed in participants from the Framingham Osteoporosis Study (1557 members of 330 mostly Caucasian pedigrees), with 401 microsatellite markers spaced on average at 10 cM. Bone mineral density (BMD) was measured at the femoral neck, trochanter, Ward's area, and lumbar spine with DXA. Our recent study (J Bone Mines Res 17 (2002), 1718) reported a number of regions with suggestive linkage to possible quantitative trait loci (QTL). The current study estimates the heterogeneity of linkage in these regions in subsamples of our pedigrees, stratified on the known biological contributors to bone mass of sex, age, and body mass index (BMI). The pedigree sample was stratified into three sets of subgroups by sex [males (age range 35- 96 years), females (29-91 years)], by age [60 or younger (29-60 years) and older than 60 (61-96 years)], and by BMI [stratified into low or high BMI, by median cut-off 27.7 in males (BMI range 17-53) and 25.8 in females (14-54)]. Heritability estimates of BMD (adjusted for age, anthropometry, nutrition, physical activity, and, in females, estrogen use) in subsamples ranged from 0.47 to 0.69. Two-point and multipoint variance component linkage analyses of BMD (using SOLAR) in subsamples supported findings of previously reported suggestive linkage results in the total sample on 8q24.13 and 14q31 (LODs>2.0). However, heterogeneity of linkage was observed on 6p21.2 and 21qter, where findings in the total sample were not supported by subsamples. On the other hand, subsample-specific maxima were found, on 4q34.1 (males), 9q22-9q31 (younger), 16p13.2 (high BMI), and 17p13.3 (older), which were not reflected by the total sample results. In conclusion, heterogeneity of QTL effects was revealed in pedigree members stratified by sex, age, and BMI; in some instances new loci were identified in subgroups. These findings may suggest that effects of genes on the determination of BMD differ between men and women, younger and older, and lean and obese adults. Evaluation of family members stratified in homogeneous groups may be warranted in genetic studies of bone mass.     

Fracture prediction from bone mineral density in Japanese men and women.

In a cohort of 2356 Japanese elderly, after adjusting for age and prevalent vertebral fracture, baseline BMD predicted the risk of spine and hip fracture with similar RR to that obtained from previous reports in whites. The RR per SD decrease in BMD for fracture declined with age. INTRODUCTION: Low bone mineral density (BMD) is one of the most important predictors of a future fracture. However, we are not aware of any reports among Japanese in Japan. MATERIALS AND METHODS: We examined the association of BMD with risk of fracture of the spine or hip among a cohort of 2356 men and women aged 47-95 years, who were followed up by biennial health examinations. Follow-up averaged 4 years after baseline measurements of BMD that were taken with the use of DXA. Vertebral fracture was assessed using semiquantitative methods, and the diagnosis of hip fracture was based on medical records. Poisson and Cox regression analysis were used. RESULTS: The incidence was twice as high in women as in men, after adjusting for age. After adjusting for baseline BMD and prevalent vertebral fracture, however, the gender difference was no longer significant. Age, baseline BMD of spine and femoral neck, and prior vertebral fracture predicted vertebral fracture and hip fracture. Loss of absolute BMD of the femoral neck predicted spine fracture, after adjusting for baseline BMD; rates of change in percent BMD, weight, height, body mass index, and age at menopause did not. The predictive value of baseline BMD for vertebral fracture risk was similar in men and women. The relative risk (RR) for vertebral fracture and hip fracture per SD decrease in BMD declined with age, after adjustment for prevalent vertebral fractures. CONCLUSIONS: Baseline BMD, loss of femoral neck BMD, and prior vertebral fracture predict the risk of spine and hip fracture in Japanese with similar RR to that obtained from previous reports in whites. The RR per SD decrease in BMD for fracture declined with age, suggesting that factors other than BMD might play a greater role in the elderly.     

Apparent bone mineral density estimated from DXA in healthy men and women

The aim of this study was to measure bone mineral density (BMD) in healthy people and examine the influence of age, anthropometry, and postmenopause on calculated bone mineral apparent density (BMAD). The study included 541 healthy subjects (249 men and 292 women), aged 20 to 79 years. Anthropometric measurements included height, weight, and body mass index (BMI). Bone mineral content (BMC) and areal BMD were measured at the lumbar spine and proximal femur, using dual-energy X-ray absorptiometry (DXA). The calculation of volumetric density relied on the formula BMAD=BMD/BA (where BA = bone area). Association between densitometric parameters and age, height, weight, and postmenopause was analyzed with multiple regression. BMC and BMD decreased with age, especially in postmenopausal women. The average annual bone loss in spine was 0.2% in both sexes, whereas femur loss was 0.5% in men and 0.3% in women. Bone area slightly increased with age in both sexes, and BMD loss after the age of 50 could be attributed to bone area increase. To minimize the effect of bone size on bone density, volumetric density and areal density were regressed to age, anthropometry, and postmenopause. Age and postmenopause were significantly associated with BMD and BMAD in the spine and femur. Furthermore, BMD showed a stronger association with height and weight than BMAD, in both regions. Weaker association of body height and weight with BMAD than with BMD suggests that BMD depends on the bone size and body size and that the different BMDs could be the consequence of the difference in those parameters.     

绝经后妇女血肌肉生长抑制素与骨密度的关系

目的探讨绝经后妇女血肌肉生长抑制素与体成份、血脂及骨密度的关系。方法纳入175名年龄在51~75岁的绝经后妇女,用双能X线吸收仪测量其骨密度(bone mineral density,BMD)及体成分。酶联免疫吸附法测定其血清肌肉生长抑制素、25羟维生素D3、甲状旁腺激素(parathyroid hormone,PTH)、骨碱性磷酸酶(bone alkaline phosphatase,BAP)、I型胶原C末端肽(type I collagen C terminal peptide,CTX)。结果与骨质疏松者相比,无骨质疏松的妇女体重指数、肥体重及瘦体重更高(P0.01)。骨质疏松妇女年龄显著大于无骨质疏松妇女(P0.01)。经年龄校正后,两组之间血BAP、CTX、25羟维生素D3、PTH、血脂成分及肌肉生长抑制素差异无统计学意义。所有测定部位BMD均与绝经年龄、肥体重及瘦体重成正比,与年龄、血BAP成反比。肌肉生长抑制素与血甘油三酯成负相关(β=-0.203,P=0.007),与体成分及所有部位骨密度无相关。结论研究数据表明血肌肉生长抑制素浓度与肌肉量及骨量无相关,需进一步研究阐明肌肉生长抑制素在调节骨代谢中的作用。