[Comparative studies of growth hormone secretion in acromegaly after isolated and combined application of insulin hypoglycemia, LH-RH- and TRH tests (author's transl)].

Growth hormone (GH) release was measured in 17 patients with active acromegaly following the administration of insulin, LH-RH and TRH given intravenously either combined or each separately. The simultaneous application of insulin and the hypothalamic releasing hormones resulted in a striking increase of plasma GH in 15 out of 17 patients. Inappropriate stimulation of GH release was found in 9 out of the 17 patients with acromegaly, when TRH was given as the only hormone; conversely this phenomenon due to LH-RH application was observed in 4 cases. In insulin-induced hypoglycemia GH release could be stimulated in 5 patients. After selective, transsphenoidal hypophysectomy, 4 of 13 patients still showed a definite stimulation of GH release after the combined use of test substances. Two of these also exhibited a comparable stimulation of GH after TRH, indicating adenoma cells remaining active after operation. The combined insulin-induced hypoglycemia/LH-RH/TRH-test is therefore advisable for patients with acromegaly, since GH release as well as other hypophyseal partial functions can be tested. The performance of individual tests is essential for evaluating selective stimulation of GH release.