Analysis of steroid conversion in vitro by testicular tissue as a means of selection of infertile males for gonadotrophic substitution therapy.

Testicular biopsy specimens from 11 infertile men were incubated in vitro with [3H]progesterone before and during long term gonadotrophic treatment. The main metabolites along the delta-4 metabolic pathway and 20 alpha-dihydro-progesterone were determined and the ratio between 20 alpha-dihydro-progesterone and 17 alpha-hydroxyprogesterone formed in vitro was calculated. In 5 patients with originally high ratios (indicating gonadotrophic understimulation), steroid metabolism changed significantly towards a more stimulated pattern. Three of these patients also showed a significant increase in sperm output and 2 of them fathered children. In 6 patients with an originally low ratio (indicating adequate gonadotrophic stimulation) no change in steroid metabolism in vitro or spermatogenesis was seen during therapy. Thus, this ratio between formed 20 alpha-dihydro-progesterone and 17 alpha-hydroxyprogesterone in vitro seems to be of value in predicting whether gonadotrophic treatment will be of clinical benefit.