Cortisol secretion in Nelson syndrome: Persistence after "total" adrenalectomy for Cushing syndrome.

In two patients who were severely pigmented (Nelson syndrome) following bilateral adrenalectomy for Cushing syndrome, symptoms of hyper-cortisolism developed while they were receiving only physiologic steroid replacement. Cortical assays proved that endogenous cortisol production had not been obliterated. Even after total adrenalectomy, steroid measurement should be performed to guard against adrenocortical excess.