The gonadotropin response of men with varicoceles to gonadotropin-releasing hormone.

The serum gonadotropin and testosterone responses to 100 micrograms of intravenously administered gonadotropin-releasing hormone (GnRH) were studied, over 180 minutes, in four groups of men: severely oligospermic men with varicoceles and sperm densities less than 10 million/ml, men with varicoceles and sperm densities greater than 10 million/ml, severely oligospermic men without varicoceles, and men of normal fertility. Each group had similar preinjection gonadotropin and testosterone levels. Following the injection of GnRH, the severely oligospermic men with varicoceles had excessive increases in luteinizing hormone and follicle-stimulating hormone levels and a slower return to preinjection values as compared with the other three groups. The responses of the other groups were not different from each other. There was not a consistent increase in testosterone levels in any group during the period of the study. These results suggest that severely oligospermic men with varicoceles have a pantesticular defect in testosterone synthesis and spermatogenesis which can be demonstrated by their response to GnRH.