Correlates of long-term hypocortisolism after transsphenoidal microsurgery for Cushing's disease.

In Cushing's disease, selective total removal of a corticotroph tumor of the pituitary regularly results in subnormal ACTH- and cortisol plasma levels. The duration of secondary adrenocortical insufficiency varies widely, with an average of 17 months in our patients. The goal of this study is to elucidate the underlying causes for the variation in duration of postoperative hypocortisolism. In this retrospective study, we evaluated 35 patients with postoperative hypocortisolism lasting more than 36 months, and compared them to 51 patients with a duration of less than 36 months. Preoperative data, intraoperative findings, and postoperative results with follow-up evaluations are presented. Extensive pituitary exploration, medial localization of the tumor, and a higher age were associated with increased risk for isolated secondary long-term hypocortisolism. The histological examination of paraadenomateous tissue identified a significantly larger amount of Crooke's cells in long-term cortisol insufficient patients. Previous pituitary surgery increased the risk for hypopituitarism. In some of our patients, the long-term adrenocortical insufficiency resolved after a period of over five years.