Plasma corticosteroids (11-OHCS) and serum immunoreactive growth hormone (IRGH) were measured in six normal subjects during an insulin tolerance test (ITT) and in four patients with normal endocrine function during the first hour of abdominal surgery. Three normal subjects were given a short dexamethasone suppression (1 mg every 6 h for five doses) followed by an ITT 2 h after the last dose. Three patients with normal endocrine function were treated identically, receiving the last dose 2 h before an operation. Five patients with bilateral adrenal hyperplasia (pituitary ACTH excess) had an ITT and were followed at surgery. During all ITTs the hypoglycaemia was adequate (blood glucose less than 40 mg/100 ml). All normal subjects responded adequately to the ITT (11-OHCS max: 26.8 ± 4.4 μg/100 ml, 2 sem; IRGH max: 35.6 ± 11.2 ng/ml), and surgery (11-OHCS max: 35.5 ± 1.7 μg/100 ml; IRGH max: 42.4 ± 12.4 ng/ml). The dexamethasone-suppressed subjects failed to show a rise in 11-OHCS during the ITT or at surgery, and the IRGH response was significantly lower compared with the non-suppressed subjects. All but one patient with Cushing's disease also failed to raise 11-OHCS levels during the ITT and at surgery; the rise in IRGH was blunted in both situations. The similarity in response to stress in (acutely) dexamethasone-suppressed normal subjects and those with Cushing's disease is striking. It suggests that feedback inhibition of increased ACTH secretion, rather than an intrinsic hypothalamic defect, may be the critical factor in the poor steroid response to a variety of stresses in Cushing's disease.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.