Aim: Late-onset hypogonadism is associated with relatively mild testosterone deficiencies. This study investigated the effects of restoring testosterone levels to normal in men with complaints of low sexual desire and erectile dysfunction.
Main outcome measures: Sexual function was assessed with the International Index of Erectile Function (IIEF) at baseline and after 24 weeks of testosterone administration.
Methods: Twenty-two hypogonadal men (mean age 58 years) with erectile dysfunction were studied. Fifteen patients had serum testosterone below 6.9 nmol/L, and seven between 7.2 and 11.7 nmol/L (reference values in our laboratory >/=12.0 nmol/L); there were considerable comorbidities. The duration of sexual complaints was on average 3.8 years. Patients received intramuscular long-acting testosterone undecanoate.
Results: In all patients, serum testosterone levels were restored to normal within 6-8 weeks. Twelve patients reported a significant improvement in the sexual desire domain (from 4.5 to 8.4) and experienced an improvement in the erectile function domain (from 12 to 25 [Questions 1-5 plus 15)], following treatment with this long-acting testosterone; in 9 of 12 patients, this occurred only after at least 12-24 weeks. The remaining 10 patients reported an improvement of sexual desire (from 4.5 to 7.5), but no significant improvement in the erectile function domain (from 12 to 14). No changes in serum prostate-specific antigen or prostate volume were noticed while receiving this long-acting testosterone preparation.
Conclusion: Restoring testosterone levels to normal in men with proven subnormal testosterone levels improves libido in most subjects, and erectile function in more than 50% of these men. It may take 12-24 weeks before the effects of testosterone become manifest.