CHANGES IN PLASMA LEVELS OF 17-HYDROXYCORTICOSTEROIDS DURING THE INTRAVENOUS ADMINISTRATION OF ACTH. II. RESPONSE UNDER VARIOUS CLINICAL CONDITIONS*

Abstract

IN a previous paper from our laboratory (1), a test was described for the evaluation of adrenocortical capacity, based on changes in the circulating levels of 17-hydroxycorticosteroids in blood plasma during the intravenous infusion of 25 i.u of adrenocorticotropic hormone (ACTH) over six hours. No significant difference was found between plasma 17-hydroxycorticosteroid levels following the administration of 25 i.u of ACTH over six hours as compared with 50 i.u of ACTH during the same period. Furthermore, we were able to show that the administration of ACTH over six hours caused maximal stimulation of the adrenal cortex in the resting human. Continuous intravenous administration of optimal doses of ACTH— 25 i.u every six hours—did not raise significantly the levels of 17-hydroxycorticosteroids above those achieved after the six-hour infusion. It was pointed out that, for the test to be quantitatively significant, a stable adrenocortical steroid environment is required. This can be found under physiologic conditions or under pathologic conditions in which a balance between production and elimination of adrenal hormone has been established.