Increased ACTH-like Activity in Plasma of Patients with Thyrotoxicosis

Abstract

Plasma from patients with thyrotoxicosis was perfused into the intact adrenal glands of hypophysectomized dogs, and the hydrocortisone content of the adrenal venous effluent was measured. In every instance there was an increased secretion of hydrocortisone over the control values, indicating ACTH-like activity of such plasma. When the patients were subsequently in the euthyroid state, no adrenocorticotropic effect of their plasma was noted. Furthermore, perfusion of L-thyroxine, triiodothyronine and TSH was without effect on hydrocortisone secretion, indicating that the stimulatory substance present in the hyperthyroid plasma was probably ACTH itself. There was no effect of either the human plasma or the thyroid hormones on the secretion of catecholamines from the adrenal medulla.