The metabolic syndrome and smoking in relation to hypogonadism in middle-aged men: a prospective cohort study.

In men, hypoandrogenism is associated with features of the metabolic syndrome. It is not known whether men with the metabolic syndrome are at a higher risk of developing hypogonadism. We therefore assessed whether the metabolic syndrome predicts development of hypogonadism 11 yr later in 651 middle-aged Finnish men participating in a population-based cohort study. Men with the metabolic syndrome at baseline as defined by the World Health Organization (n = 114, 20%) had a 2.6-fold increased risk of developing hypogonadism as defined by total testosterone levels less than 11 nmol/liter at the 11-yr follow-up independent of age, smoking, and other potential confounders. Further adjustment for body mass index (OR, 2.0; 95% CI, 1.1-3.8) or baseline total testosterone levels (OR, 1.9; 95% CI, 1.0-3.4) attenuated the association. The association of the metabolic syndrome with hypogonadism as defined by calculated free testosterone levels less than 225 pmol/liter was similar, but weaker. The adjusted decrease in testosterone concentrations during the 11-yr follow-up was also greater in men with than without the metabolic syndrome. Smokers had a nonsignificantly lower risk of developing hypogonadism during follow-up, whereas a decrease in smoking increased the risk of hypogonadism. The metabolic syndrome predisposes to development of hypogonadism in middle-aged men. Prevention of abdominal obesity and the accompanying metabolic syndrome in middle age may decrease the risk of hypogonadism in men, especially in those who quit smoking.