Effects of synthetic corticotropin-releasing factor in normal individuals and in patients with hypothalamic-pituitary-adrenocortical disorders

Abstract

Plasma adrenocortical hormone (ACTH) and cortisol response to four dose levels (25, 50, 100 and 300 micrograms) corticotropin-releasing factor (CRF) were studied in 5 healthy men, and the response to 100 micrograms CRF in 12 patients with various disorders of the hypothalamic-pituitary-adrenocortical function. In normals, mean plasma ACTH and cortisol concentration rose at all dose levels of CRF and peaked at 30 and 60 min respectively. The increment in plasma cortisol at 60 and 90 min was significantly higher on 100 and 300 micrograms CRF than on 25 micrograms, but the total cortisol concentration was not. Seven patients had Cushing's syndrome. In 2 patients with adrenocortical carcinoma the basal plasma ACTH was suppressed. After CRF a small increase was seen in plasma ACTH and cortisol in one patient successfully treated with mitotane, while the other patient did not respond. In 1 patient with ectopic ACTH syndrome an increase in plasma ACTH 15 min after CRF was not accompanied by any increase in plasma cortisol. One patient with bilateral multinodular adrenocortical hyperplasia did not respond to CRF. The plasma ACTH and cortisol response to CRF was supernormal in 2 patients with Cushing's disease, while a third patient responded in the normal range. In 2 patients with Nelson's syndrome the plasma ACTH response was excessive. Two out of three hypophysectomized patients did not respond to CRF, while one patient with a slightly positive response to hypoglycemia also responded (subnormally) to CRF. Our data indicate that CRF in doses of 50-100 micrograms will be a valuable substance in the differential diagnosis of Cushing's syndrome. Some overlap in the response is, however, seen between patients with Cushing's disease and other patients with Cushing' syndrome. CRF will possibly be of value also for the diagnosis of secondary adrenocortical failure.