THE USE OF INTRAVENOUS ACTH: A STUDY IN QUANTITATIVE ADRENOCORTICAL STIMULATION*

Abstract

The adrenal cortical response to the intraven. admn. of ACTH was studied quantitatively in over 200 patients and normal subjects. Eosinopenia and the rise in urinary 17-ketosteroid excretion were used as indices of the degree of activation obtained. Dose-response and time-response relationships were examined. It appeared that, when the duration of the intraven. infusion of ACTH was kept constant, the adrenal stimulation obtained increased with the amt. of ACTH infused, up to a critical ACTH dosage over and above which no further response was elicited. In 8 subjects with normal adrenocortical function this critical dosage was 20 I.U. or less for an 8-hr. duration of the infusion. When the dosage was kept constant and the duration of intraven. admn. was varied, a linear increase in adrenocortical stimulation occurred with increasing duration of admn. The use of an 8_hr. infusion of 20 I.U. of ACTH intraven. as a test for the evaluation of the immediate adrenocortical reserve was illustrated. Clinical patterns of response to as many as 30 daily infusions of ACTH were presented as yielding some insight into the potential adrenal cortical reserve. The marked metabolic effects of the prolonged continuous intraven. infusion of ACTH were shown. The use of intraven. ACTH in the assay of the hormone in human subjects and in therapy has been documented by appropriate examples. It has been stressed that, using the intraven. infusion technic, microgram quantities of highly-purified ACTH prepns. may be tested for overall metabolic activity in human subjects.