Immediate postoperative cortisol levels accurately predict postoperative hypothalamic-pituitary-adrenal axis function after transsphenoidal surgery for pituitary tumors

Accurate assessment of the hypothalamic-pituitary-adrenal (HPA) axis is critical for the appropriate management of patients with pituitary adenoma after transsphenoidal surgery. We examine the role of immediate postoperative cortisol levels to assess hypothalamic-pituitary-adrenal axis (HPA) axis function post-operatively. We performed preoperative cortrosyn stimulation test (CST) and measured immediate postoperative serum cortisol levels in 100 patients undergoing 104 transsphenoidal surgeries. These results were compared to those of the CST at 4-6 weeks postoperatively, which served as a measure of HPA axis function. The ability of immediate postoperative, day of surgery (DOS) cortisol levels to predict normal HPA axis function was determined using standard predictive analytic methods and confusion matrix calculations. We found that postoperative, DOS cortisol level ≥15 μg/dL is a sensitive and accurate predictors of normal postoperative HPA axis function, with a sensitivity of 98%, an accuracy of 97%, and a positive predictive value of 99%. Our data suggest that an immediate, postoperative, DOS cortisol level ≥15 μg/dL predicts distant, normal, post-operative HPA axis function following transsphenoidal surgery.