Abstract / Summary
Abstract Purpose We aimed to evaluate the diagnostic performance of morning serum cortisol nadir (MSCN), within the first week after pituitary surgery (PS), to exclude secondary adrenal insufficiency (SAI) at short- and mid-term postoperative follow-up. Methods We conducted a retrospective cohort study including adults undergoing transsphenoidal PS at a tertiary center, without Cushing’s disease or unknown hypothalamic-pituitary-adrenal axis (HPAA) status. The lowest morning serum cortisol value within the first week after PS was recorded. SAI diagnosis at 1–3 months and 9–12 months was based on clinical judgment. Results We included 116 patients undergoing 129 PS. SAI was present in 30/112 (24%) and 23/112 (21%) 1–3 and 9–12 months, after PS, respectively. At 1–3 months, median early postoperative MSCN was 1.30 (IQR 0.67–3.73) in patients with SAI vs. 11.50 (8.14–15.40) µg/dL in those with an intact HPAA (p < 0.001); at 9–12 months, 1.18 (0.60–3.60) vs. 10.90 (7.70-14.65) µg/dL, respectively (p < 0.001). The ROC curves showed an area under the curve of 0.967 and 0.888 for SAI at 1–3 and 9–12 months, respectively. A MSCN threshold of 6.7 µg/dL (185 nmol/L) yielded sensitivities of 96.7% and 91.3%, specificities of 90.7% and 85.4%, and negative predictive values of 98.9% and 97.4% for predicting intact HPAA function at 1–3 and 9–12 months follow-up, respectively. Conclusion A MSCN ≥ 6.7 µg/dL within the first postoperative week reliably excludes SAI at both short- and mid-term follow-up. Following prospective validation, this threshold may support glucocorticoid replacement therapy before hospital discharge.