Direct conversion from long-acting testosterone replacement therapy to Natesto allows for spermatogenesis resumption: Proof of concept.

Long-acting testosterone replacement therapy (TRT) suppresses spermatogenesis. A short-acting TRT, Natesto, maintains spermatogenesis in some men. This study evaluated hormonal and semen parameters converting men from long-acting TRT to Natesto. Baseline hormones, again on long-acting TRT and 1 month after converting to Natesto, as well as semen parameters 3 months after converting to Natesto were assessed. Twenty-seven men were directly converted from long-acting forms of TRT to Natesto. Mean duration on long-acting TRT was 24.3 ± 19 months. Testosterone levels were similar on long-acting forms of TRT and Natesto, however; E2 levels were significantly lower on Natesto. Ten men had semen analyses demonstrating azoospermia while on long-acting TRT, the remainder were presumed to be azoospermic or severely oligospermic which has been well established as an effect of long-acting TRT. All 27 men had resumption of spermatogenesis with a mean sperm concentration of 50.7 million/ml after converting to Natesto, considered within the fertile range. One couple achieved a pregnancy 4 months after converting to Natesto. Hypogonadal men on long-acting TRT interested in resumption of spermatogenesis may convert directly to Natesto for an opportunity to do so while remaining on a form of TRT and achieving lower E2 levels.