Human pancreatic growth hormone releasing hormone fails to stimulate human growth hormone both in Cushing's disease and in Cushing's syndrome due to adrenocortical adenoma.

An absent or severely blunted hGH response to an i.v. bolus injection (100 micrograms) of human pancreatic growth hormone releasing hormone (hpGRF 1-44) was found in seven female patients with Cushing's syndrome (five with pituitary dependent Cushing's disease and two due to an adrenal adenoma) and four men with pituitary dependent Cushing's disease. Three of the female and three of the male patients had an adequate hypoglycaemia after insulin administration. All these patients showed an absent or blunted hGH response after insulin induced hypoglycaemia. The GHRH data in these patients are in agreement with those in older literature on hGH responsiveness to stimuli such as L-dopa, arginine and insulin induced hypoglycaemia. It is concluded that hypercortisolism inhibits hGH release to various stimuli at the pituitary level.