Testosterone replacement therapy in males with erectile dysfunction.

Erectile dysfunction (ED) is defined as the inability to achieve or maintain an erection sufficient for satisfactory sexual performance. Endogenous testosterone is critical for normal libido; however, studies have also demonstrated a potentially important role with respect to the erectile process. The prevalence of testosterone deficiency ranges from 1.7% to 35% in patients with ED, and age is a common factor linking ED and testosterone deficiency. By 2025, global estimates are that there will be 356 million men >65 years. Age-associated testosterone deficiency is characterized by symptoms such as ED, and low serum testosterone. Randomized, placebo controlled studies have established the utility of testosterone replacement therapy (TRT) for the restoration of serum testosterone levels to the normal range in hypogonadal males; however, well designed studies are limited with respect to specific evaluation of the role of TRT as monotherapy in improving erectile function. In addition, recent literature suggests a possible role for TRT in combination with phosphodiesterase-5 (PDE-5) inhibitors for men with ED. The following review describes the potential roles of testosterone in erectile physiology, examines the relationship between testosterone deficiency and ED, and reviews published literature evaluating the use of TRT in hypogonadal males with a diagnosis of ED.