Low-dose ACTH test for evaluation of hypothalamus-pituitary-adrenal axis preoperatively and 3-month follow-up in non-functioning pituitary adenomas.

Background: Peri-operative glucocorticoids are routinely administered to patients undergoing trans-sphenoidal surgery for non-functional pituitary adenomas (NFPA) irrespective of hypothalamus-pituitary-adrenal (HPA) axis status.
Purpose: Evaluation of HPA axis before and 12 weeks after endoscopic trans-sphenoidal adenomectomy (E-TSA) utilizing low-dose (1 μg) ACTH stimulation test (LDACTH) to determine the need for glucocorticoid administration in patients with NFPA. We also determined the factors that can predict occurrence of hypocortisolism at 12 weeks after surgery.
Methods: Sixty-three consecutive patients with NFPA requiring surgical excision were enrolled in this study. Glucocorticoids were administered to patients with demonstrable hypocortisolism [preoperative peak cortisol < 16 μg/dL during LDACTH test, postoperative day 3 (POD-3) 0800 hrs Cortisol < 8 μg/dL or stimulated cortisol (LDACTH) < 16 μg/dL at 12 weeks].
Results: Hypocortisolism was present in 43 patients (68.2%) pre-operatively and persisted in 33 patients (52.4%) on POD-3. Thirty-three patients (52.4%) had hypocortisolism at 12 weeks after surgery. Eleven patients (17.4%) did not require glucocorticoids during the entire study period and 30 patients (47.6%) did not require glucocorticoids after 3 months. None of the patients developed adrenal crisis during the study. Hypocortisolism on the third post-operative day was the single significant predictor of hypocortisolism at 12 weeks after the surgery. There was a significant correlation between POD-3 0800 hrs cortisol ≥ 8μg/dL and stimulated cortisol (LDACTH) ≥16μg/dL at 12 weeks (r = 0.62, p < 0.0001). POD-3 0800 hrs cortisol ≥ 8 μg/dL had 73% sensitivity and 79% specificity in predicting eucortisolism at 12 weeks.
Conclusions: HPA function is preserved in significant proportion of NFPA patients undergoing E-TSA. Perioperative glucocorticoids should be given only in patients with demonstrable preoperative hypocortisolism on 1 μg ACTH test. Postoperative day 3 0800 hrs cortisol is a reasonable predictor of HPA axis status at 12 weeks after surgery.