Stimulation of growth hormone release by luteinizing hormone-releasing hormone in two males with isolated gonadotropin deficiency.

The pituitary functions were tested in two males with the typical clinical pictures of hypogonadism. The secretions of ACTH, TSH, GH and prolactin in these patients were maintained within normal limits, whereas they had markedly diminished LH and FSH levels in plasma. Plasma LH and FSH responses to the intravenous injection of 100 mug LH-RH were absent or limited. After 7-day treatment with intravenous infusion of 400 mug LH-RH, they showed normal or improved responses to the intravenous injection of 100 mug LH-RH. Thus, the diagnosis of isolated gonadotropin deficiency due to a hypothalamic lesion was established. Initially, the standard LH-RH test (100 mug intravenous injection) did not elicit a rise in plasma GH levels. However, it was of interest that after the repeated stimulation by 400 mug LH-RH, GH response to the intravenous injection of 100 mug LH-RH was observed in both patients.