Restorative increases in serum testosterone levels are significantly correlated to improvements in sexual functioning.

It is recognized that testosterone (T) levels decrease in men with age, as does sexual function. We hypothesize that T supplementation in hypogonadal men with sexual dysfunction will restore certain elements of sexual function. Hypogonadal male subjects (total T < or = 300 ng/dL, n = 406, mean age 58 years) reporting one or more symptoms of low testosterone were randomized to T gel (50 mg/d and 100 mg/d), T patch, or placebo. Twenty-four-hour pharmacokinetic profiles for T were obtained. The 3 primary end points evaluated at 30 and 90 days posttreatment included a significant change in the frequency of intercourse and nighttime erections per 7-day week as well as a change in sexual desire measured on a Likert-type scale and calculated as a mean daily score. At day 30, a significant increase from baseline in sexual desire was noted for those on 100 mg/d T gel compared with those on 50 mg/d T gel, T patch, or placebo (1.2 vs 0.4, 0.7, and 0.4, respectively). A significant increase from baseline in the frequency of nighttime erections was also noted for those on 100 mg/d T gel compared with those on 50 mg/d T gel or placebo (51% of subjects in the 100 mg/d T gel group had an increase in frequency vs 30% for the 50 mg/d T gel group and 26% in the placebo group). Finally, a significant increase from baseline in the frequency of intercourse was evidenced for those on 100 mg/d T gel compared with those on T patch or placebo (39% of subjects in the 100 mg/d T gel group had an increase in frequency vs 21% for the T patch group and 24% in the placebo group). Similar results were seen for 100 mg/d T gel at day 90 for sexual desire and nighttime erections vs placebo. These data demonstrate a clear relationship between restoring serum T concentrations and improvement in certain parameters of sexual function. We propose that threshold T levels are needed in order to significantly affect improvements in sexual functioning.