Transsphenoidal Pituitary Adenoma Resection: Do Early Post-Operative Cortisol Levels Predict Permanent Long-Term Hormone Deficiency?

Abstract Objective: Transsphenoidal surgery provides a minimal invasive treatment for pituitary adenoma. Our aim is to evaluate the endocrinological outcomes after adenoma resection, and to identify prognostic factors for an impaired hypothalamic-pituitary-adrenal- axis function -(HPA) and the reliability of postoperative early morning serum cortisol measurements.Methods: Retrospective analysis of all patients treated for pituitary adenoma from April 2006 to January 2019 in our neurosurgical department. Pituitary function was assessed pre- and postoperatively as well as at 6 weeks to 12 weeks and at 1-year follow-up.Results: 211 patients were included. 9% of the patients recovered from a preoperative adrenal insufficiency, 10.4% developed a new need for hormone substitution, and a long-term deficiency of the hypothalamic-pituitary-adrenal-axis was observed in 30.9%. Cortisol measurements 5 days after surgery had a lower area under the curve (AUC) than cortisol levels detected after 6 to 12 weeks (AUC 0.740 vs. AUC 0.808) in predicting a secondary adrenal insufficiency. The cut-off value determined for cortisol measured after 6 weeks was 6.95 µg/dl (sensitivity of 94%, specificity of 68%).Conclusion: Postoperative early morning cortisol levels seem to be less sensitive and specific in predicting long-term hormone deficiency than measurements after 6 weeks and 1 year, emphasizing the importance of endocrine follow-up testing.