Serum estradiol is associated with lean mass in elderly Swedish men

Abstract

Objective: Association studies in men have shown that androgens are inversely related to fat measures, while the relation between sex steroids and lean mass remains unclear.We, therefore, investigated the associations between serum sex steroid levels and body composition in elderly men with a main focus on lean mass measures. Design and methods: A cross-sectional survey of a population-based cohort of 3014 elderly men, aged 69-80 years (Osteoporotic Fractures in Men study, Sweden). Serum levels of testosterone and estradiol (E2) were measured by mass spectrometry, sex hormone-binding globulin (SHBG) levels were measured by IRMA, and measures of body composition were obtained by dual-energy X-ray absorptiometry. Results: Total aswell as free serumtestosterone associated independently inversely (P < 0.001),while total aswell as free serum E2 associated independently directly (P < 0.001) with total body fatmass and trunk fat mass. Serum SHBG associated independently inversely with central fat distribution. Serum E2 and free E2 butnot serumtestosterone or free testosterone levels associated positivelywithleanmass (P < 0.01). Elderly men within the lowest quartile of free E2 had 0.5 kg less lean mass in the legs than subjects within the highest quartile, while the subjects in the different quartiles of free testosterone did not differ in leanmass. Conclusions: Serum E2, but not serum testosterone, is directly associated with leanmass in this large study of elderly Swedish men. In addition, serum SHBG is associated with central fat distribution and we confirmed that serum testosterone is inversely associated with fat mass. © 2010 European Society of Endocrinology.