Maintenance of spermatogenesis in hypogonadotropic hypogonadal men with human chorionic gonadotropin alone

Objective: It is generally accepted that both gonadotropins LH and FSH are necessary for initiation and maintenance of spermatogenesis. We investigated the relative importance of FSH for the maintenance of spermatogenesis in hypogonadotropic men. Subjects and methods: 13 patients with gonadotropin deficiency due to idiopathic hypogonadotropic hypogonadism (EM), Kallmann syndrome or pituitary insufficiency were analyzed retrospectively. They had been treated with gonadotropin-releasing hormone (GnRH) (n = 1) or human chorionic gonadotropin/human menopausal gonadotropin (hCG/hMG) (n = 12) for induction of spermatogenesis. After successful induction of spermatogenesis they were treated with hCG alone for maintenance of secondary sex characteristics and in order to check whether sperm production could be maintained by hCG alone. Serum LH, FSH and testosterone levels, semen parameters and testicular volume were determined every three to six months. Results: After spermatogenesis had been successfully induced by treatment with GnRH or hCG/hMG, hCG treatment alone continued for 3-24 months. After 12 months under hCG alone, sperm counts decreased gradually but remained present in all patients except one who became azoospermic. Testicular volume decreased only slightly and reached 87% of the volume achieved with hCG/hMG. During treatment with hCG alone, FSH and LH levels were suppressed to below the detection limit of the assay. Conclusion: Once spermatogenesis is induced in patients with secondary hypogonadism by GnRH or hCG/hMG treatment, it can be maintained in most of the patients qualitatively by hCG alone, in the absence of FSH, for extended periods. However, the decreasing sperm counts indicate that FSH is essential for maintenance of quantitatively normal spermatogenesis.