The Postoperative Basal Cortisol and CRH Tests for Prediction of Long-Term Remission from Cushing's Disease after Transsphenoidal Surgery

Context: Selective adenomectomy via transsphenoidal surgery induces remission of Cushing's disease (CD) in most patients. Although an undetectable postoperative serum cortisol (< 2 mu g/dl) has been advocated as an index of remission, there is no consensus on predictors of recurrence. Objective: We hypothesized that patients with subnormal cortisol (2-4.9 mu g/dl) might achieve long-term remission and that postoperative responses to CRH might predict recurrence. Design, Setting, and Participants: We prospectively studied CD patients with initial remission after adenomectomy or hemihypophysectomy (n = 14). Long-term recurrence (n = 39) or remission (n = 293) was assigned by laboratory results, glucocorticoid dependence, or patient survey at a mean of 10.6 yr after surgery. Intervention and Main Outcome Measures: Postoperatively, morning cortisol was measured on d 3-5, and cortisol and ACTH responses to ovine CRH were assessed around d 10. Results: Follow-up duration was median 11 yr (range 1-22.8 yr). Fewer patients achieved a cortisol nadir below 2 mu g/dl (87%) than below 5 mu g/dl (98%), yet recurrence rates were similar (< 2 mu g/dl, 9.5%; < 5 mu g/dl, 10.4%; 2-4.9 mu g/dl, 20%; not significant). CRH-stimulated cortisol (P < 0.002) and ACTH(P = 0.04) values were higher for the recurrence than the remission group. However, no basal or stimulated ACTH or serum or urine cortisol cutoff value predicted all who later recurred. Conclusions: A postoperative cortisol below 2 mu g/dl predicts long-term remission after transsphenoidal surgery in CD. Remission in those with intermediate d 3-5 postoperative cortisol values (2-4.9 mu g/dl) suggests that these patients do not require immediate reoperation. However, because no single cortisol cutoff value excludes all patients with recurrence, all require long-term clinical follow-up. (J Clin Endocrinol Metab 96: 2057-2064, 2011)