Blood Corticotropin (Acth) Levels in Cushing’s Disease*

The present study was undertaken in search of a definitive answer to the question of whether the pituitary secretes abnormal quantities of corticotropin (ACTH) in Cushing’s disease (hypercortisolism due to bilateral adrenal hyperfunction). It was postulated that if the primary disorder in Cushing’s disease were a derangement of pituitary function it should not be corrected by removal of the adrenal glands. In such patients it should then be possible to control plasma cortisol levels while observing plasma ACTH levels. Two groups of patients were studied: 10 who had been treated for Cushing’s disease by bilateral adrenalectomy, and 8 who had Addison’s disease without prior history of Cushing’s disease. Although the amounts of cortisol administered and the plasma 17-hydroxycorticosteroid values were similar for the two groups, blood ACTH levels were consistently higher in the patients with Cushing’s disease. It is concluded that for any given level of plasma cortisol, the patient with Cushing’s disease maintains a higher-than-normal level of blood ACTH.