Plasma Adrenocorticotrophic Hormone in Addison's Disease and its Modification by the Administration of Adrenal Steroids
Adrenal steroids exert a depressant effect on the release of pituitary adrenocorticotrophic hormone. It is therefore of interest to ascertain whether there is an increased secretion of ACTH in Addison's disease because of the deficiency of adrenal steroids in the plasma in this condition. The concentration of ACTH was determined by measuring the production of corticosteroids in the hypophysectomized dog as a measure of the amount of ACTH in plasma obtained from humans. In normal adults the amount of ACTH circulating in the plasma is so small that 20 to 31 ml of plasma does not contain sufficient ACTH to cause a significant increase in adrenal corticosteroids in adrenal venous blood collected from the test animal. Fifty-one determinations in 32 patients with adrenal insufficiency revealed a mean concentration of ACTH in the plasma which was significantly elevated over that found for plasma from 16 controlled samples obtained from normal subjects. The increased concentration of ACTH found in 10 patients with Addison's disease was significantly reduced by the intravenous infusion of hydrocortisone. It was not possible to correlate the increased concentration of ACTH in the plasma of patients with Addison's disease with the clinical manifestations or duration of the disease. The relative suppressive effect of various amounts and kinds of corticosteroids was studied.