Coexistence of hypothalamic and pituitary failure after successful pituitary surgery in Cushing's disease?

The type of secondary adrenal failure, which occurs after successful pituitary surgery in Cushing's disease was studied using CRH administration. Eight patients with Cushing's disease were studied in the immediate postoperative period (9-18 days) of successful pituitary surgery. The results in these patients were compared with those in 13 healthy subjects, 7 patients with secondary adrenal failure of the pituitary type and 9 patients with secondary adrenal failure of the hypothalamic type. In all postoperative patients with Cushing's disease, except one, clear ACTH and cortisol responses occurred after CRH, demonstrating hypothalamic adrenal failure in these patients. This demonstration of hypothalamic adrenal failure after neurosurgery strongly argues against a pivotal role for endogenous CRH in the pathogenesis of Cushing's disease in these patients. The mean ACTH response to CRH in the postoperative patients with Cushing's disease was significantly lower than that in patients with adrenal failure of the hypothalamic type. This suggests the presence of pituitary failure in the postadenomectomy patients. In conclusion, this study provides arguments that the secondary adrenal failure after adenomectomy in Cushing's disease is caused by both hypothalamic and pituitary failure.