Insulin stimulation tests in pituitary dependent Cushing's syndrome after complete adrenalectomy

The present study shows that in a group of 6 euadrenal patients, previously treated by complete adrenalectomy for pituitary dependent Cushing's syndrome, the stress stimulus of insulin induced hypoglycaemia is followed by a plasma ACTH response which is of similar magnitude as the response obtained with lysin-vasopressin. Both observations indicate that the central nervous system-pituitary axis is basically normal in pituitary dependent Cushing's syndrome as assessed by insulin induced hypoglycaemia. It is concluded that non-responsiveness of the pituitary-adrenocortical system to insulin induced hypoglycaemia in untreated patients with pituitary dependent Cushing's syndrome does not represent a fundamental defect of the stress mechanism, but is due to hypercorticism per se.