Prediction of adrenal insufficiency after pituitary surgery: a retrospective study using beckman access cortisol assay

Purpose: Identifying patients requiring glucocorticoid replacement therapy after pituitary surgery is challenging as the tests commonly used for the diagnosis of secondary adrenal insufficiency (SAI) are not recommended in the immediate postoperative period. There are controversial data on the role of postoperative days' morning cortisol, with no specific data for each cortisol assay. The aim of this study is to investigate the reliability of 8.00 a.m. cortisol of the first and second postoperative days in predicting SAI. Methods: Data of patients underwent pituitary surgery in Humanitas Research Hospital in Italy, from March 2017 to August 2022, were retrospectively analyzed. Definitive diagnosis of SAI was made through ACTH test 1 µg six weeks after surgery. Cortisol was measured through Beckman Access Cortisol and the diagnosis of SAI was made if cortisol peak was below 14.8 µg/dL (408 nmol/L) at 30 or 60 min after stimulus. Results: Of the sixty-four patients enrolled, seven developed SAI. The ROC curves demonstrated that both first- and second-day postoperative 8.00 a.m. cortisol predict SAI (AUC 0.94 and 0.95, respectively). The optimal thresholds were 15.6 µg/dL (430.3 nmol/L; accuracy 89%) for the first day and 11.5 µg/dL (317.2 nmol/L, accuracy 81%) for the second day. Patients who developed SAI had larger tumors (p = 0.004) and lower fT4 (p = 0.038) before surgery. Conclusions: Clinicians might rely on the first- and second- postoperative days 8.00 a.m. cortisol to identify patients to discharge with glucocorticoid replacement therapy waiting for the confirmation of SAI through the ACTH test.