Importance of fat mass and lean mass on bone health in men: the Fourth Korean National Health and Nutrition Examination Survey (KNHANES IV)

Association of insulin resistance with bone mineral density in a nationwide health check-up population in China

INTRODUCTION

Insulin resistance (IR) is closely associated with cardio-metabolic diseases. However, the impact of IR on bone mass remains obscure. The present study is to evaluate the association between the triglyceride-glucose (TyG) indicated IR and bone mass in a nationwide health check-up population in China.

METHODS

We conducted a retrospective cross-sectional study including 788,247 participants and a longitudinal cohort study in 8770 participants who had repeated measurements of TyG index and bone mass in at least a 2-year follow-up period. The restricted cubic splines and logistic models were used to analyze the association between IR and bone mass in the cross-sectional study. The Cox model was applied to evaluate the relationship between baseline IR and the subsequent incidence of low bone mass and osteoporosis in the longitudinal study.

RESULTS

In the cross-sectional study, the TyG index had positive correlations with low bone mass, osteoporosis, or both after adjusting for confounding factors (all P < 0.001). In the longitudinal cohort study, the baseline TyG index was significantly associated with the incidence of low bone mass, osteoporosis, or both during the follow-up period, with hazard ratios (HRs) of 1.56 (95 % confidence interval [CI]: 1.25, 1.93, P < 0.05), 1.66 (95%CI: 1.06, 2.59, P < 0.05), and 1.55 (95%CI: 1.27, 1.88, P < 0.05) after adjusting for confounding factors, respectively.

CONCLUSIONS

These results suggest that IR indicated by TyG is significantly associated with an increased risk of low bone mass and osteoporosis. Therefore, bone mass monitoring and early prevention strategies may be needed in individuals with IR to prevent the occurrence of low bone mass and osteoporosis.

Adipopenia is associated with osteoporosis in community-dwelling non-underweight adults independent of sarcopenia

The effect of fat deficit on bone metabolism is understudied. This study showed that low body fat percent (adipopenia) in non-underweight community adults was associated with elevated odds of osteoporosis independent of low lean mass, highlighting potential clinical importance of adipopenia as an osteoporosis risk factor particularly in older adults.

PURPOSE

Although underweight is risk factor for osteoporosis, the association of low body fat percent (adipopenia) with osteoporosis in non-underweight adults remains unclear.

METHODS

Among individuals aged ≥ 50 years with body mass index ≥ 18.5 kg/m² in the Korean National Health and Nutrition Examination Survey 2008-2011, appendicular lean mass (ALM) and body fat percent (BFP) were measured using dual-energy x-ray absorptiometry. Low lean mass was defined as ALM/height² < 7.0 kg/m² and < 5.4 kg/m² in men and women, respectively. Osteoporosis was defined as a bone mineral density (BMD) T-score ≤ -2.5 at the lumbar spine, femoral neck, or total hip. Participants were grouped into adipopenia (BFP < 17% in men; < 30%, in women; 1 standard deviation below the mean), normal, and obesity (BFP > 30% in men; > 40% in women) groups.

RESULTS

Of the 5,830 participants (women 50.2%, mean age 63.9 years), 793 had adipopenia. The adipopenia group had a higher prevalence of osteoporosis (31%) than the normal (21%) or obesity groups (27%; p < 0.001). The presence of adipopenia was associated with 61% elevated odds of prevalent osteoporosis (p < 0.001) independent of low lean mass and covariates, which remained robust using different thresholds for adipopenia. Individuals with adipopenia and low lean mass had 3.5-fold elevated odds of osteoporosis compared to those with normal lean mass and fat percent. The association between adipopenia and osteoporosis was stronger in older women compared to middle-aged women (OR 1.93 vs. 0.99, P for interaction = 0.023).

CONCLUSION

Adipopenia was associated with osteoporosis in non-underweight adults, independent of low lean mass and covariates.

Mitochondrial β-oxidation of adipose-derived fatty acids by osteoblasts fuels parathyroid hormone-induced bone formation

The energetic costs of bone formation require osteoblasts to coordinate their activities with tissues, like adipose, that can supply energy-dense macronutrients. In the case of intermittent parathyroid hormone (PTH) treatment, a strategy used to reduce fracture risk, bone formation is preceded by a change in systemic lipid homeostasis. To investigate the requirement for fatty acid oxidation by osteoblasts during PTH-induced bone formation, we subjected mice with osteoblast-specific deficiency of mitochondrial long-chain β-oxidation as well as mice with adipocyte-specific deficiency for the PTH receptor or adipose triglyceride lipase to an anabolic treatment regimen. PTH increased the release of fatty acids from adipocytes and β-oxidation by osteoblasts, while the genetic mouse models were resistant to the hormone's anabolic effect. Collectively, these data suggest that PTH's anabolic actions require coordinated signaling between bone and adipose, wherein a lipolytic response liberates fatty acids that are oxidized by osteoblasts to fuel bone formation.

The inverse association of body adiposity index and bone health in the older adults: A report from a developing country

The ageing process influences body composition and could be related to bone health. The current study was set out to evaluate the association between body adiposity index (BAI) and bone health in older adults. This is a cross-sectional study performed on 178 elderly persons (51 men and 127 women) with a mean age of 67.04 (range: 60-83) who was referred to the determined 25 health centres in Tehran. The anthropometric measurements were done. Further, serum 25-hydroxy vitamin D (25(OH)D), parathormone (PTH), high-sensitivity C-reactive protein (hs-CRP), osteocalcin and urine C-terminal telopeptide I (CTX-I) were collected. The mean of body mass index (P < .001), body weight (P = .002), body fat (P < .001), waist circumference (P < .001), hip circumference (P < .001), urine CTX-I concentration (P = .011), 25(OH)D (P = .030), was higher in the highest BAI category in comparison with the lowest one. BAI was negatively correlated with urine CTX-I concentration (r=-0.165, P = .028). Moreover, linear regression showed an inverse association between BAI with urine CTX-I (β = -0.165, P = .025) and 25(OH)D (β = -0.039, P = .029). Moreover, the percentage of body fat was positively associated with serum hs-CRP (β = 0.026, P = .002). Our study showed a significant inverse association between BAI with urinary CTX-I which shows the effect of obesity on bone health. This study suggests that more clinical and prospective studies for monitoring body fat may have some favourable impacts on bone health.

Incidence and predictors of fractures in older adults with and without obesity defined by body mass index versus body fat percentage

PURPOSE

The aim of this study was to determine and compare risk factors associated with incident fractures in older adults with and without obesity, defined by both body mass index (BMI) and body fat percentage.

METHODS

1,099 older adults (mean ± standard deviation age = 63.0 ± 7.5) years, participated in this prospective cohort study. Obesity status at baseline was defined by BMI (≥30 kg/m²) obtained by anthropometry and body fat percentage (≥30% for men and ≥40% for women) assessed by dual-energy X-ray absorptiometry (DXA). Total hip and lumbar spine areal bone mineral density (aBMD) were assessed by DXA up to five years. Incident fractures were self-reported up to 10 years.

RESULTS

Prevalence of obesity was 28% according to BMI and 43% according to body fat percentage. Obese older adults by BMI, but not body fat percentage, had significantly higher aBMD at the total hip and spine compared with non-obese (both p-value<0.05). Obese older adults by body fat percentage had significantly higher likelihood of all incident fractures (OR: 1.71; CI:1.08, 2.71) and non-vertebral fractures (OR: 1.88; CI:1.16, 3.04) compared with non-obese after adjusting for confounders. Conversely, obese older adults by BMI had a significantly lower likelihood (OR: 0.54; CI:0.31, 0.94) of non-vertebral fractures although this was no longer significant after adjustment for total hip aBMD (all p-value > 0.05). Mediation analysis confirmed that aBMD meditated the effects of BMI, but not body fat percentage, on all incident fractures. Higher baseline falls risk score was the only consistent predictor of increased likelihood of incident fracture in obese individuals only, according to both BMI and body fat percentage (both p-value<0.05).

CONCLUSIONS

Obesity defined by body fat percentage is associated with increased likelihood of incident fractures in community-dwelling older adults, whereas those who are obese according to BMI have reduced likelihood of incident fracture which appears to be explained by higher aBMD. Falls risk assessment may improve identification of obese older adults at increased risk of incident fractures.

Osteoporosis in cirrhotics before and after liver transplantation: relation with malnutrition and inflammatory status

Background: Liver cirrhosis is associated with osteoporosis and liver transplantation (LT) with increased bone loss. This study aimed to in LT candidates investigate the potential relation between bone mineral density (BMD) and BMD loss in those who undergo LT, with malnutrition, systemic inflammation, and hormonal status.Methods: We included 102 consecutively recruited cirrhotic LT candidates between May 2004 and April 2007. BMD was assessed by means of dual energy X-ray absorptiometry (DXA). Malnutrition was defined by means of anthropometry and assessment of recent weight loss. In 75/102 patients, serum-thyroid stimulating hormone (TSH), free triiodthyronine (T3) and free thyroxine (T4) and growth hormone (GH), cortisol, free testosterone, dehydroepiandrosterone sulfate, estradiol, interleukin-6, and tumor necrosis factor (TNF)-α was assessed. Overall 57/102 patients received a LT and 47/102 were followed for one year post-LT. At follow-up, nutritional status and BMD were assessed in all patients (n = 47) while 34/47 had available blood samples for analysis.Results: Forty (40%) LT- candidates had osteopenia or osteoporosis and 34 (38%) were malnourished. Malnutrition was associated with osteopenia/osteoporosis (odds ratio: 3.5, 95% CI 1.4, 9.9). Hip BMD Z-score decreased -0.25 (95% CI -0.41, -0.09) from baseline to one year post-LT. High baseline TNF-α correlated with a more marked decline in BMD (Partial correlation (r) = -0.47, p < .05) as did high baseline cortisol levels (r = -0.49, p < .05).Conclusion: Malnutrition in liver cirrhosis seems to be associated with osteopenia/osteoporosis, and systemic inflammation (higher TNF-α) and systemic stress (higher cortisol) to bone loss in patients who undergo LT.

Inter - Relationship of Awareness, Knowledge, Attitude, Some Socio-Economic Variables and Osteoporosis in Sample of Egyptian Women

BACKGROUND

Osteoporosis is a global health problem, and its prevalence is rapidly increasing worldwide.

AIM

The aim was to assess the awareness concerning some nutritional and socio-economic variables causes the disease in a sample of Egyptian women.

METHODS

This study was done among 116 female volunteers. They were divided into two groups, pre and post-menopausal, with a mean age of 42.05 ± 8.25 & 51.13 ± 5.82 years and mean body mass index (BMI) of 30.83 ± 8.18 & 34.24 ± 8.80 kg/m². A standardised questionnaire, socioeconomic and food frequency chart were used to assess osteoporosis and food intake awareness. Bone mineral density was measured by dual-energy X-ray absorptiometry (DEXA). Statistical analyses were done using simple percentage and Chi-square test.

RESULTS

Data revealed that a low percentage of pre and post-menopausal women were aware of osteoporosis and fracture (16.67% & 12.96% and 30.65% & 19.35%). They had incomplete knowledge about the sources and the beneficial effects of consumption of calcium and vitamin D rich diet. Non-osteoporotic women showed more awareness. Odds ratio predict occupations and educations levels as risk factors for osteoporosis.

CONCLUSION

Awareness about osteoporosis and consumption healthy diet were low among Egyptian women, so it is important to implement special osteoporosis prevention program.

Association between Body Fat and Bone Mineral Density in Normal-Weight Middle-Aged Koreans

Background

Osteoporosis and osteopenia are characterized by reduced bone mineral density (BMD) and increased fracture risk. Although the risk of fractures is higher in underweight people than in overweight people, the accumulation of body fat (especially abdominal fat) can increase the risk of bone loss. This study aimed to evaluate the association between body fat percentage and BMD in normal-weight middle-aged Koreans.

Methods

This study included 1,992 adults (mean age, 48.7 years; 52.9% women). BMD and body fat were measured using dual-energy X-ray absorptiometry. Multiple linear regression analyses and analysis of covariance were used to assess the association between BMD and body fat. Body fat percentage was grouped by cut-off values. The cut-off values were 20.6% and 25.7% for men with a body mass index of 18.5–22.9 kg/m², while the cut-off values were 33.4% and 36% for women.

Results

Body fat percentage tended to be negatively associated with BMD. Increased body fat percentage was associated with reduced BMD in normal-weight middle-aged adults. The effects of body fat percentage on BMD in normal-weight individuals were more pronounced in men than in women.

Conclusion

There was a negative correlation between BMD and body fat percentage in middle-aged Korean men and women with normal body weight. This association was stronger in men than in women.

The Role of Overweight and Obesity on Bone Health in Korean Adolescents with a Focus on Lean and Fat Mass

As the associations between pediatric overweight/obesity and bone health remain controversial, we investigated the effects of overweight/obesity as well as lean mass (LM) and fat mass (FM) on bone parameters in adolescents. Bone parameters were evaluated using dual-energy X-ray absorptiometry (DXA) data of 982 adolescents (aged 12-19 years) from the Korea National Health and Nutrition Examination Survey (2009-2010). Z-scores for LM, FM, bone mass, bone mineral density (BMD), and bone mineral apparent density (BMAD) using Korean pediatric reference values were used for analysis. Adolescents with overweight/obesity had significantly higher bone mass and density of the total-body-less-head (TBLH), lumbar spine, and femur neck than underweight or normal-weight adolescents (P < 0.001) after adjusting for vitamin D deficiency, calcium intake, and insulin resistance in both sexes. LM was positively associated with bone parameters at all skeletal sites in both sexes (P < 0.001). FM was negatively related to TBLH BMD in boys (P = 0.018) but was positively associated to BMD and BMAD of the lumbar spine and femur neck in girls. In conclusion, overweight/obesity and LM play a positive role in bone health in adolescents. The effect of FM on bone parameters is sex- and site-specific.

Fat Mass Is Positively Associated with Estimated Hip Bone Strength among Chinese Men Aged 50 Years and above with Low Levels of Lean Mass

This study investigated the relationships of fat mass (FM) and lean mass (LM) with estimated hip bone strength in Chinese men aged 50-80 years (median value: 62.0 years). A cross-sectional study including 889 men was conducted in Guangzhou, China. Body composition and hip bone parameters were generated by dual-energy X-ray absorptiometry (DXA). The relationships of the LM index (LMI) and the FM index (FMI) with bone phenotypes were detected by generalised additive models and multiple linear regression. The associations between the FMI and the bone variables in LMI tertiles were further analysed. The FMI possessed a linear relationship with greater estimated hip bone strength after adjustment for the potential confounders (p < 0.05). Linear relationships were also observed for the LMI with most bone phenotypes, except for the cross-sectional area (p < 0.05). The contribution of the LMI (4.0%-12.8%) was greater than that of the FMI (2.0%-5.7%). The associations between the FMI and bone phenotypes became weaker after controlling for LMI. Further analyses showed that estimated bone strength ascended with FMI in the lowest LMI tertile (p < 0.05), but not in the subgroups with a higher LMI. This study suggested that LM played a critical role in bone health in middle-aged and elderly Chinese men, and that the maintenance of adequate FM could help to promote bone acquisition in relatively thin men.

Associations Between Fat Mass, Lean Mass, and Knee Osteoarthritis: The Fifth Korean National Health and Nutrition Examination Survey (KNHANES V)

As little is known about the associations between body composition (fat mass and lean mass) and knee OA, especially regarding body parts (upper body and lower limbs), the purpose of this study was to identify the association between the former and the prevalence of the latter according to body parts. This study was designed as a cross-sectional analysis, with 4194 people (1801 men and 2393 women) from the fifth Korean National Health and Nutrition Examination Survey (KNHANES V, 2010-2011) included. Body composition (fat mass and lean mass) was measured by using dual-energy X-ray absorptiometry, and knee OA was diagnosed based on the level of Kellgren-Lawrence grade. In multivariate logistic regression analysis, upper body composition was not significantly correlated with radiographic knee OA (P > 0.05), while participants with higher lean mass of lower limbs were less likely to have radiographic knee OA (aOR 0.57; 95 % CI 0.32-0.99). In stratified analysis, participants with higher lean mass of lower limbs were less likely to have a radiographic knee OA in 40-54 kg (P for trend = 0.05) and 55-70 kg stratum (P for trend = 0.03), while this trend slightly attenuated in 70-85 kg stratum (P for trend = 0.15). In conclusion, the increase in lean mass of lower limbs is inversely related to the prevalence of knee OA while upper body composition is not. This study suggests that the lean mass of lower limbs might be associated with reduction in the risk of knee OA.

The effects of sarcopenia and obesity on femur neck bone mineral density in elderly Korean men and women

Objectives

We aimed to clarify the relationship between fat, muscle, and bone in elderly men and women.

Methods

We analyzed 1373 men and 1803 women who were older than 65 years from the 2008–2010 Korea National Health and Nutritional Examination Surveys. Body composition and femur neck bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry. Sarcopenia was defined as an appendicular skeletal muscle index (SMI) below one standard deviation (SD). Obesity was classified by fat mass index (FMI). Osteoporosis was defined as a BMD of 2.5 SD below that of femur neck BMD.

Results

SMI and FMI were positively correlated with femur neck BMD. In multiple regression analysis, SMI (β = 0.302 in men, β = 0.154 in women; p < 0.001 each) and FMI (β = 0.079 in men, β = 0.179 in women; p = 0.003 and p < 0.001 respectively) had a positive relationship with femur neck BMD. Men with sarcopenia were 3.89 times more likely to develop osteoporosis. Women with sarcopenia were 1.87 times more likely to develop osteoporosis. Sarcopenia was more clinically significant in the development of osteoporosis in men with a fat deficit and women with excess fat.

Conclusions

Muscle mass and fat mass were identified as determinants of femur neck BMD in men and women. Among them, muscle mass of men and fat mass of women are the most important determinants of femur neck osteoporosis.

Relationship of sarcopenia and body composition with osteoporosis

The purpose of the study is to investigate the relationship between sarcopenia and body composition and osteoporosis in cohorts of three different races with a total of 17,891 subjects. Lean mass and grip strength were positively associated with bone mineral densities (BMDs). Subjects with sarcopenia were two times more likely to have osteoporosis compared with normal subjects.

INTRODUCTION

The relationship between sarcopenia and osteoporosis is not totally clear. First, the present study assessed this relationship by using two different definitions for sarcopenia. Second, we examined the associations of body composition (including muscle mass as a major and important component) and muscle strength on regional and whole-body BMDs.

METHODS

In total, 17,891 subjects of African American, Caucasian, and Chinese ethnicities were analyzed. Sarcopenia was defined by relative appendicular skeletal muscle mass (RASM) cut points and also by the definition of the European Working Group on Sarcopenia in Older People (low RASM plus low muscle function). Multiple regression analyses were conducted to examine the association of fat mass, lean mass (including muscle mass), and grip strength with regional and whole-body BMDs. Multivariate logistic regression analysis was performed to explore the association between sarcopenia and osteopenia/osteoporosis.

RESULTS

BMDs were positively associated with lean mass and negatively associated with fat mass, after controlling for potential confounders. Grip strength was significantly associated with higher BMDs. Each standard deviation (SD) increase in RASM resulted in a ~37 % reduction in risk of osteopenia/osteoporosis (odds ratio (OR) = 0.63; 95 % confidence interval (CI) = 0.59, 0.66). Subjects with sarcopenia defined by RASM were two times more likely to have osteopenia/osteoporosis compared with the normal subjects (OR = 2.04; 95 % CI = 1.61, 2.60). Similarly, subjects with sarcopenia (low muscle mass and low grip strength) were ~1.8 times more likely to have osteopenia/osteoporosis than normal subjects (OR = 1.87; 95 % CI = 1.09, 3.20).

CONCLUSIONS

High lean mass and muscle strength were positively associated with BMDs. Sarcopenia is associated with low BMD and osteoporosis.

The impact of fragility fractures on health-related quality of life in patients with primary sclerosing cholangitis

BACKGROUND

Osteoporosis occurs frequently in patients with chronic cholestatic liver diseases, yet data are scarce regarding the prevalence of osteoporosis and fragility fractures and their impact on Health-Related Quality of Life (HRQoL) in Primary Sclerosing Cholangitis (PSC).

OBJECTIVES

We aimed to assess Bone Mineral Density (BMD), physical activity and incidence of fragility fractures in patients with PSC. We also sought associations between prior fractures and HRQoL.

PATIENTS AND METHODS

The study was performed on 33 patients (11 females, 22 males) aged 35.3 ± 13 years. HRQoL was assessed by Short Form (SF)-36, Primary Biliary Cirrhosis (PBC)-40 and PBC-27 questionnaires. BMD was measured by densitometry in the lumbar spine and hip. Physical activity was assessed by questionnaire.

RESULTS

In 32% of patients, BMD measured in the hip or spine was below 1.0 Standard Deviation. A history of fragility fractures (distal forearm and ribs) was reported in six patients (18%). In SF-36 assessment, patients with fractures had lower scores in the role functioning, general health and vitality domains and Physical Component Summary (PCS) than those without fractures. Prior fractures adjusted for gender and PSC duration were associated with lower PCS and Mental Component Summary (MCS) scores. Symptoms and fatigue (assessed by PBC) and prior fractures were inversely associated with MCS (P = 0.007).

CONCLUSIONS

In middle-aged subjects with PSC, we found a high rate of non-vertebral fractures and a moderately decreased BMD in lumbar spine and hip. Fragility fractures had an impact on physical and mental aspects of HRQoL.

Association between dietary fat intake and bone mineral density in Korean adults: data from Korea National Health and Nutrition Examination Survey IV (2008 ∼ 2009)

We determined the relation between dietary fat intake and bone mineral density, and our study showed that low- as well as high-fat diet was associated with the risk of osteoporosis. Our study provides significant evidence of the specific dietary components that may be important modifiable factors for the prevention of osteoporosis.

INTRODUCTION

Osteoporosis and osteoporosis-related fractures have become major public health problems. It is important to understand the various factors that influence bone health and to prevent osteoporosis by correcting modifiable risk factors for the disease. Previous studies suggested that dietary habits and body composition were potent factors associated with bone mineral density. The aim of this study was to determine the independent effect of dietary fat intake on bone mineral density while controlling for other possible confounders, including fat mass and lean body mass.

METHODS

This study was based on data obtained in the Fourth Korea National Health and Nutrition Examination Survey. After serial exclusion of subjects according to the selection criteria, 7,192 subjects were included in our analysis. We divided the study population into quintiles according to dietary fat calorie/total calorie intake and compared the adjusted means of bone mineral density between quintiles.

RESULTS

The bone mineral density was higher in men and women with a medium fat energy intake compared to those with a low- and high-fat energy intake, but the finding was statistically significant only in women. The results were valid after controlling for body fat percentage and lean body mass.

CONCLUSIONS

We found that dietary fat intake is an independent modifiable risk factor for osteoporosis, regardless of body fat or lean body mass, especially in women. However, further investigations with accurate analyses of food intake and nutritional consumption, in addition to long-term follow-up data, are necessary to recommend an osteoporosis-preventive diet in Koreans.

Association between the awareness of osteoporosis and the quality of care for bone health among Korean women with osteoporosis

Background

The prevalence of osteoporosis is increasing and is a socio-economic burden worldwide. Although screening tests for osteoporosis in Korea are easily accessible, this condition remains undertreated. Evaluating post-diagnostic behavior changes may be helpful for improving the quality of care for bone health in osteoporotic patients.

Methods

After reviewing the Fourth Korean National Health and Nutrition Examination Survey 2008–2009, 1,114 women with osteoporosis aged >50 years were included in this cross-sectional study. Factors related to bone health were categorized into the following groups: (1) behavioral health (smoking, alcohol consumption, and physical activity); (2) measured factors (lean body mass [kg], appendicular skeletal muscle mass [kg], and serum vitamin D level [nmol/L]); and (3) nutritional factors (calcium intake, vitamin/mineral supplementation, and healthy supplementary food). Logistic regression analysis and analysis of covariance was conducted after adjusting for age, education, income, residential area, height, weight, and self-perceived health using a weighted method.

Results

Doctors diagnosed 39.5% of patients with osteoporosis, and these patients were compared with the control group. The awareness group, who had been diagnosed with osteoporosis by a doctor, had a lower proportion of smokers and higher serum vitamin D level than the control group, who had never been diagnosed with osteoporosis. No other associations were found for quality of bone health care variables. The awareness group had higher odds ratios of vitamin/mineral replacement and healthy supplementary food but no other differences were observed, indicating the patients’ beliefs in bone health care do not follow the recommended clinical guidelines (e.g. higher physical activity, lower alcohol consumption).

Conclusion

To improve the quality of care for bone health in osteoporotic patients, an initial step should be the development of post-diagnostic procedures such as patient counseling and education through a multi-team care approach.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-334) contains supplementary material, which is available to authorized users.

Gender-specific associations of appendicular muscle mass with BMD in elderly Italian subjects

Currently used diagnostic measures for sarcopenia are based on the evaluation of appendicular skeletal muscle mass (ASMM) divided by height-squared (ASMMI). This study aimed to investigate the associations between different operational definitions of appendicular muscle mass and BMD at different skeletal sites in aging Italian men and women. In 1199 consecutive healthy Italian subjects, aged 55 years or more (854 women, age 64.2 ± 6.4 years and 165 men, age 65.3 ± 6.1 years), we measured BMD at the lumbar spine (LS-BMD), at femoral neck (FN-BMD),at total hip (TH-BMD), at total body (WB-BMD) and at the right hand (H-BMD) and body composition parameters [ASMM, ASMMI, ASMM/Weight, total lean mass and total fat mass by DXA]. In all subjects, we also measured sex hormones, 25-hydroxyvitamin D and bone turnover markers. In men, both ASMM and ASMMI were positively correlated with BMD at all sites, whereas in women, ASMM and ASMMI did not show any significant correlation with BMD. In men, multiple regression analyses showed that ASMM was positively associated (p < 0.01) with FN-BMD, TH-BMD and H-BMD; however, these associations were no longer present when lean mass was included. In women, both fat mass and lean mass were found positively associated with BMD at all sites. In conclusion, among the different operational measures of the ASMM, only ASMM was significantly associated with BMD in elderly men, but not in elderly women.