Sex Differences in the Associations of Testosterone and Sex Hormone-Binding Globulin With Metabolic Syndrome in Middle-Aged and Elderly Koreans - The Namwon Study

Background: We investigated the sex-dependent associations of testosterone and sex hormone-binding globulin (SHBG) levels with metabolic syndrome (MetS). Methods and Results: We conducted a cross-sectional study of 9,424 community-dwelling adults aged 45-74 years (median age, 63.7 years). MetS was defined according to the updated version of the National Cholesterol Education Program Adult Treatment Panel III criteria. Serum total testosterone (TT) and SHBG levels were determined using a chemiluminescent microparticle immunoassay, and free testosterone (FT) concentrations were calculated. In a multivariate analysis, TT levels were inversely associated with MetS in men (odds ratio [OR] of each standard deviation increase in the logarithmic value, 0.70; 95% confidence interval [CI], 0.65-0.76), whereas they were positively associated in women (OR, 1.17; 95% CI, 1.10-1.24). FT levels were positively associated with MetS in women only (OR, 1.39; 95% CI, 1.30-1.49). However, SHBG levels were negatively associated with MetS in both men (OR, 0.57; 95% CI, 0.52-0.61) and women (OR, 0.61; 95% CI, 0.57-0.66). Conclusions: Our data showed that higher TT levels were associated with a reduced prevalence of MetS in men and an elevated prevalence of MetS in women. Higher SHBG levels were associated with decreased prevalence of MetS in both sexes. These results suggest sex differences in the associations of endogenous testosterone and SHBG with MetS. (Circ J 2013; 77: 734-740)