Long-term effect of D-Trp6-luteinizing hormone-releasing hormone on testicular size and luteinizing hormone, follicle-stimulating hormone, and testosterone levels in hypothalamic hypogonadotropic males.

Six men, ages 18 to 34 years, with hypothalamic hypogonadotropism were treated with D-Trp6-luteinizing hormone-releasing hormone (10 micrograms intramuscularly on alternate days) for a period of 6 months. They underwent an intravenous luteinizing hormone-releasing hormone (LH-RH) test (50 micrograms/sq m) before and after 1, 3, and 6 months of treatment. During the first 3 months of therapy, the mean (+/- standard deviation) testicular volume increased from 3.5 +/- 1.0 ml to 6.0 +/- 2.0 ml, but decreased to 5.0 +/- 1.0 ml after 6 months. A significant increase in the plasma LH response to LH-RH over pretreatment levels was noted after 1 month (10.2 +/- 4.2 mIU/ml versus 1.6 +/- 1.0 mIU/ml, P less than 0.001) and 3 months (3.0 +/- 1.6 mIU/ml, P less than 0.01) with a subsequent decline to pretreatment levels after 6 months of treatment. The follicle-stimulating hormone response to LH-RH was not significant. It is concluded that D-Trp6-LH-RH induced an initial stimulation in these patients but, probably because of the excessively high dose used, a paradoxical inhibitory response was obtained after 3 months of therapy.