Prevalence of symptomatic androgen deficiency in men 30 and 79 yr of age is 5.6% and increases substantially with age. The aging of the U.S. male population will cause a large increase in the burden of symptomatic androgen deficiency. Future work should address the clinical significance of low testosterone levels in asymptomatic men.

Little is known about the descriptive epidemiology of androgen deficiency. In this study, we sought to address this issue by providing estimates of the crude and age-specific prevalence and incidence rates of androgen deficiency in a randomly sampled population-based cohort of middle-aged and older men. Data on androgen deficiency (defined using both signs/symptoms plus total and calculated free testosterone) were available for n = 1691 (baseline) and n = 1087 (follow-up) men from the Massachusetts Male Aging Study. Crude and age-specific prevalence and incidence rates were calculated. Based on these estimates, projections for the number of cases of androgen deficiency in the 40- to 69-yr-old U.S. male population were computed. Estimates of the crude prevalence of androgen deficiency at baseline and follow-up were 6.0 and 12.3%, respectively. Prevalence increased significantly with age. From baseline age-specific prevalence data, it is estimated that there are approximately 2.4 million 40- to 69-yr-old U.S. males with androgen deficiency. The crude incidence rate of androgen deficiency was 12.3 per 1,000 person-years, and the rate increased significantly (P < 0.0001) with age. Based on these incidence data, we can expect approximately 481,000 new cases of androgen deficiency per year in U.S. men 40-69 yr old.

Both chronological aging and changes in health and lifestyle factors are associated with declines in serum T. Comorbidities and lifestyle influences may be as strongly associated with declining T levels as is aging itself over the short- to midterm. These results suggest the possibility that age-related hormone decline may be decelerated through the management of health and lifestyle factors.