Associations between circulating reproductive hormones and SHBG and prevalent and incident metabolic syndrome in community-dwelling older men: The concord health and ageing in men project

Abstract

Context: The causal relationship between metabolic syndrome and reproductive hormones is unclear. Objective: This study sought to examine the cross-sectional, longitudinal, and predictive associations between reproductive hormones and SHBG and metabolic syndrome in older men. Design, Setting, and Participants: Men ages 70 years and older from the Concord Health and Ageing in Men Project study (n = 1705) were assessed at baseline and 2-year follow-up. At baseline, T, dihydrotestosterone (DHT), estradiol, and estrone were measured by liquid chromatographytandem mass spectrometry, and SHBG, LH, and FSH by immunoassay. Metabolic syndrome was defined using the P National Cholesterol Education Program (NCEP) Adult Treatment Panel III criteria. Results: In cross-sectional data, significant associations between each of T, SHBG, DHT, and calculated free testosterone (cFT) with the metabolic syndrome remained significant after multivariate adjustment. In longitudinal analyses, however, only lower SHBG was significantly associated with incident metabolic syndrome over the 2-year follow-up (P for linear trend = .04). Conclusions: Although low serum T, DHT, SHBG, and cFT were associated cross-sectionally with metabolic syndrome among community-dwelling older men, over a 2-year follow-up period only SHBG remained significant after multivariate adjustment. This suggests that lowered circulating androgens (T and DHT) may be biomarkers rather than causally related to incident metabolic syndrome.