Persistence of spermatogenesis in hypogonadotropic hypogonadism treated with testosterone.

The case histories are reported of two patients who had persistent spermatogenesis as evidenced by normal semen analyses and fertility in the face of hypogonadotropic hypogonadism and testosterone administration. When not receiving testosterone, both men consistently had normal or low serum gonadotropin levels. Since pooled serum testosterone levels were low simultaneously, these "normal" gonadotropin values are still consistent with hypogonadotropic hypogonadism. Standard testosterone replacement therapy maintained secondary sex characteristics and, surprisingly, spermatogenesis in both men. A review of the literature revealed conflicting evidence concerning the roles of gonadotropins and testosterone in affecting spermatogenesis. In applying this evidence to our patients, it appears that gonadotropins may have only a minimal role in maintaining fertility in patients with established spermatogenesis and "adequate" testosterone levels; it also appears that relatively low doses of exogenous testosterone may maintain or enhance spermatogenesis in certain individuals. We conclude that men with acquired hypogonadotropic hypogonadism should not be presumed to be sterile and that a larger study of fertility in these patients is necessary. Until then, we recommend that the semen of these patients be analyzed at the time of diagnosis and during treatment with testosterone.