The prevalence of low sex steroid hormone concentrations in men in the Third National Health and Nutrition Examination Survey (NHANES III)

Background Physiologic processes during ageing leading to multi-morbidity and diseases that increase risk of premature death may be influenced by ageing-associated changes in endogenous hormone production. Objective To evaluate the decline in sex steroid hormone levels across age and estimate the number of US men 40+ years old who may have low hormone levels. Design We measured serum testosterone, oestradiol and sex hormone binding globulin by immunoassay in 1351 men 20+ years old in Third National Health and Nutrition Examination Survey. We estimated free hormones by mass action. Results Free testosterone declined most rapidly with age (a 2% decline in geometric mean concentration occurred after ageing 1.3 years), followed by total testosterone (2.4 years), free oestradiol (4.1 years) and total oestradiol (8.1 years). These hormone changes with age translated into 25.0% and 30.2% of men 70+ years old having low total (which we defined as <10.4 nM) and free (<0.17 nM) testosterone, respectively, and 8.3% and 23.9% having low total (<73.4 pM) and free (<2.2 pM) oestradiol. Using population size projections between the 2000 and 2010 Censuses, we estimated that 8.4 (95% CI 4.7-12.2), 6.2 (3.1-9.2) and 6.0 (3.1-9.0) million men 40+ years old may have low total testosterone, free testosterone and free oestradiol, respectively. The prevalences were only modestly lower in men without prevalent chronic diseases. Conclusion Although no consensus exists for defining low hormone levels in ageing men, a substantial number of US men may have low sex steroid hormone levels, possibly putting them at risk for adverse health consequences and premature death.