Growth Hormone (GH)-Releasing Activity of TRH and GH-Lowering Effect of Dopaminergic Drugs in Acromegaly: Homogeneity in the Two Responses

Abstract

In 29 acromegalic patients growth hormone (hGH) responses were studied following administration of synthetic TRH (200 μg, iv), l-dopa (500 mg orally), TRH following l-dopa and after administration of 2-Bromo-α-ergocryptine (CB 154, 2.5 mg orally). A majority of patients fell into two groups, those in whom growth hormone changed substantially with each test and those in whom growth hormone levels remained stable. A minority of these acromegalics responded to only one of the test situations. In the same patients, the application of the classical functional tests, viz., insulin hypoglycemia, arginine infusion and glucose loading, did not allow a distinction between “responders” and “nonresponders.” These results indicate that combined application of TRH and DA-like drugs is a better tool for investigating the secretory pattern of acromegalic patients than usual dynamic tests. Use of the anomalous hGH responses to TRH and to dopaminergic drugs in acromegaly appears to offer additional promise for further study of the so far obscure pathophysiology of this disease.