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.