Luteinizing hormone pulse frequency and in vitro bioactivity in male idiopathic infertility

We investigated 51 patients with idiopathic oligospermia and 10 control subjects. Blood samples were collected every 20 minutes from 10 P.M. to 10 A.M. and luteinizing hormone (LH) pulsatility was analyzed. A pool of all samples obtained from each subject was used to measure bioactive LH in an in vitro mouse Leydig cell bioassay and immunoactive LH in an immunoradiometric assay. Mean immunoactive LH pulse frequency was higher and mean bioactive to immunoactive LH ratio was lower in infertile men than in controls. There was a significant negative correlation between bioactive LH to immunoreactive LH ratio and LH pulse frequency. These data indicate that the defect in the gonadal axis in oligospermic men resides not in the hypothalamic-pituitary function but rather in the testis itself.