Testosterone and estradiol among older men

Context: Testosterone and estradiol levels decline with age in men. This change may affect multiple clinical outcomes, but there have been few reports of the distribution and correlates of testosterone and estradiol concentrations in elderly men. Objective: The purpose of these studies was to assess sex steroid levels in a large cohort of older men. Design: We conducted a cross-sectional cohort evaluation. Setting: Community-dwelling men were studied at six academic medical centers in the United States. Participants: The Osteoporotic Fractures in Men Study is a prospective cohort of men aged at least 65 yr. In these studies, a randomly selected stratified subsample of 2623 participants was analyzed. Main Outcome Measures: We assessed levels of total and free testosterone and estradiol and SHBG. Results: Age was inversely associated with free testosterone and free estradiol levels (P for trend = 0.001 for both). Notably, at any age, there was substantial variation in levels of each hormone. Free testosterone levels were lower in men with greater body mass index, lower SHBG, and poorer self-reported health status and in those of Asian race. Free estradiol concentrations were lower in men with lower body mass index and higher SHBG levels. Free estradiol and free testosterone were modestly correlated (r = 0.20; P < 0.001), but at any level of free testosterone, there was considerable variation in free estradiol levels. Conclusions: This is the largest cohort of older men in which sex steroid levels are available, and it demonstrates that testosterone and estradiol, and their free fractions, tend to decline with age even among older men. However, substantial variation is also present. The relationships between sex steroid levels and their consequences in aging are likely to be complex.