Effect of various acth preparations and of metyrapone on the secretion of growth hormone in normal subjects and in hypopituitary patients

To evaluate the possible effect of ACTH upon circulating growth hormone levels, various forms of ACTH and metyrapone have been administered to 7 groups of 8 or more normal adults as well as to 37 children including 27 hypopituitary patients. In normal adults, significant increases in plasma corticoids occurred after all ACTH preparations were administered while growth hormone concentrations were significantly elevated after 100 and 25 U of synthetic ACTH iv and after 100 U porcine ACTH iv, but not after 100 U synthetic ACTH im or bovine ACTH iv. In contrast, the children, whether normal or hypopituitary, showed no growth hormone increase following administration of any of the ACTH preparations mentioned above. Neither oral (750 mg) nor iv (7.5 mg/kg/hr) metyrapone administration was followed by growth hormone release in adult subjects with increased compound S concentrations indicative of endogenous ACTH release. The lack of GH rise after endogenous ACTH release produced by metyrapone would indicate that a physiologic role of growth hormone release after increased ACTH is unlikely. While growth hormone release occurs after synthetic ACTH in a significant number of adult individuals, the response is too inconsistent to be used to test growth hormone response, and would certainly be entirely misleading in children.