The postoperative cortisol stress response following transsphenoidal pituitary surgery: a potential screening method for assessing preserved pituitary function.

The ability to reliably identify patients with new hypocortisolemia acutely following pituitary surgery is critical. We aimed to quantify the postoperative cortisol stress response following selective transsphenoidal adenomectomy, as a marker for postoperative preservation of functional pituitary gland. Records of 208 patients undergoing transsphenoidal operations for pituitary lesions were reviewed. Patients with Cushing's Disease, preoperative adrenal insufficiency, and those receiving intraoperative steroids were excluded. To quantify the postoperative stress response, the ∆ cortisol index was defined as the postoperative day (POD) 1 morning cortisol minus the preoperative morning cortisol level. The incidence of new hypocortisolemia requiring glucocorticoid replacement upon hospital discharge was also recorded. Fifty-two patients met inclusion criteria. The mean preoperative, POD1, and POD2 cortisol levels were 16.5, 29.2, and 21.8 μg/dL, respectively. Morning fasting cortisol levels on POD1 ranged from 4.2 to 73.0 μg/dL. The ∆ cortisol index ranged from -19.0 to +56.2 (mean +12.7 μg/dL). Five patients (9.6%) developed new hypocortisolemia on POD 1-3 requiring glucocorticoid replacement; only one required long-term replacement. The mean ∆ cortisol in patients requiring postoperative glucocorticoids was -2.8 μg/dL, compared with +14.4 μg/dL in patients without evidence of adrenal insufficiency (p = 0.005). Of the 32 patients (61.5%) with a ∆cortisol >25 μg/dL, none developed postoperative adrenal insufficiency. The postoperative cortisol stress response, as quantified by the ∆ cortisol index, holds potential as a novel and complimentary screening method to predict preservation of normal pituitary function and acute development of new ACTH deficiency following transsphenoidal pituitary surgery.