Low free testosterone is associated with loss of appendicular muscle mass in Japanese community-dwelling women

Aim: Sarcopenia accelerates frailty syndrome, and adversely affects activities of daily living and quality of life. The aim of the present study was to assess longitudinal relationships between baseline androgen and muscle mass changes in Japanese women. Methods: Data were collected from 539 community-dwelling, Japanese women aged 40-79 years at baseline who participated in both baseline and follow-up examinations of a longitudinal study of aging (mean duration 8.3 years). Appendicular skeletal muscle mass was measured with dual-energy X-ray absorptiometry at baseline and follow-up examinations. The cut-off point for sarcopenia was a skeletal muscle index (appendicular skeletal muscle mass/height(2)) <5.46 kg/m(2). Participants with sarcopenia at baseline were excluded. Thus, 430 women were included. Total testosterone, free testosterone and dehydroepiandrosterone-sulphate were measured by radioimmunoassay at baseline. The androgens were categorized into three groups by serum levels. Multiple logistic regression models were fit to determine the associations between androgens and sarcopenia while controlling for baseline age, body mass index, leisure-time physical activity, nutritional intakes (total energy, total protein, vitamin D), serum C-reactive protein levels, medical histories (heart disease, osteoporosis, rheumatoid arthritis), menopause and smoking habit. Results: The fully adjusted odds ratio of sarcopenia for the low-free testosterone group (<0.7 pg/mL) compared with the high-free testosterone group (>= 1.2 pg/mL) was 3.59 (95% confidence interval 1.25-10.34). Sarcopenia was not significantly related to total testosterone or dehydroepiandrosterone-sulphate. Conclusion: A low-free testosterone level appears to be a significant predictor of the risk for loss of appendicular muscle in Japanese women.