Leydig cell density and function and their relation to gonadotropins in infertile oligospermic men with varicocele.

Circulating gonadotropin and testosterone levels in infertile men with varicocele and sperm counts of less than 10(7)/ml were correlated with testicular Leydig cell density and in vitro testosterone synthesis. A significant correlation was found between Leydig cell density and both plasma testosterone levels and in vitro testosterone synthesis. Luteinizing hormone (LH) levels paralleled the in vitro testosterone synthesis. Although in the majority of patients, in vitro testosterone synthesis and Leydig cell density were low, plasma testosterone and LH levels were within the normal range. The only abnormal circulating hormonal level was high follicle-stimulating hormone in the most severely oligospermic patients. No difference were found between the right and left testes with regard to in vitro testosterone synthesis or Leydig cell density, and no correlation with patient age or site or degree of varicocele could be demonstrated. These findings suggest that Leydig cell dysfunction was the mechanism responsible for the oligospermia and infertility of these patients.