Residual adrenocortical function after bilateral adrenalectomy for pituitary-dependent Cushing's syndrome

The incidence of residual, functioning adrenal tissue in patients treated by total bilateral adrenalectomy for Cushing's disease is not known. Between 1962 and May 1988 50 patients with Cushing's disease were treated by bilateral adrenalectomy. Of these patients, 29 underwent surgery between 1962 and 1980, when bilateral adrenalectomy was the treatment of first choice in our hospital in patients with pituitary-dependent Cushing's syndrome. In 37 patients the presence or absence of cortisol-producing tissue could be evaluated (follow-up period, median and range, 8.3 and 0.1-18.9 yr). Evidence of functioning cortisol-producing tissue (plasma cortisol level > 50 nmol/L after stopping glucocorticoid and mineralocorticoid substitution therapy for 24 h) was found in 9 patients (24%). Plasma cortisol levels in these 9 patients varied between 60 and 330 nmol/L (mean +/- SD, 180 +/- 100 nmol/L). Signs and symptoms of recurrent Cushing's syndrome were present in only 1 patient. There was no difference in plasma ACTH levels and duration of follow-up between the patients with and without evidence of functioning cortisol-producing tissue. In all 9 patients detectable aldosterone levels indicated endogenous mineralocorticoid production, whereas in only 1 patient adrenaline was detectable in the circulation. In 8 of the 9 patients suspected of functioning cortisol-producing tissue we performed a stimulation test with synthetic ACTH (1-24). In 2 patients plasma cortisol levels rose, in 6 they remained virtually unchanged. Although we found clinically relevant signs and symptoms of Cushing's syndrome in only 1 of the 50 patients, the relatively high incidence of residual, functioning adrenal tissue after "total" adrenalectomy for pituitary-dependent Cushing's syndrome necessitates continuous surveillance for recurrent Cushing's syndrome. There is no place for routine administration of full replacement doses of glucocorticoids after total adrenalectomy.