Recovery of the Hypothalamo-Pituitary-Adrenal Axis After Transsphenoidal Adenomectomy for Non-ACTH-Secreting Macroadenomas

CONTEXT: Secondary adrenal insufficiency is a potential complication of transsphenoidal adenomectomy (TSA). Most centers test recovery of the hypothalamo-pituitary-adrenal (HPA) axis after TSA, but, to our knowledge, there are no data predicting likelihood of recovery or the frequency of later recovery of HPA function. OBJECTIVE: To assess timing and predictors of HPA axis recovery after TSA. DESIGN: Single-center, retrospective analysis of consecutive pituitary surgeries performed between February 2015 and September 2018. PATIENTS: Patients (N = 109) with short Synacthen test (SST) data before and at sequential time points after TSA. MAIN OUTCOME MEASURES: Recovery of HPA axis function at 6 weeks, and 3, 6, and 9 to12 months after TSA. RESULTS: Preoperative SST indicated adrenal insufficiency in 21.1% Among these patients, 34.8% recovered by 6 weeks after TSA. Among the 65.2% (n = 15) remaining, 13.3% and 20% recovered at 3 months and 9 to 12 months, respectively. Of the 29% of patients with adrenal insufficiency at the 6-week SST, 16%, 12%, and 6% subsequently recovered at 3, 6, and 9 to 12 months, respectively. Preoperative SST 30-minute cortisol, postoperative day 8 cortisol, and 6-week postoperative SST baseline cortisol levels above or below 430 nmol/L [15.5 μg/dL; AUC ROC, 0.86]; 160 nmol/L (5.8 μg/dL; AUC ROC, 0.75); and 180 nmol/L (6.5 μg/dL; AUC ROC, 0.88), were identified as cutoffs for predicting 6-week HPA recovery. No patients with all three cutoffs below the threshold recovered within 12 months after TSA, whereas 92% with all cutoffs above the threshold recovered HPA function within 6 weeks (OR, 12.200; 95% CI, 5.268 to 28.255). CONCLUSION: HPA axis recovery can occur as late as 9 to 12 months after TSA, demonstrating the need for periodic reassessment of patients who initially have SST-determined adrenal insufficiency after TSA. Pre- and postoperative SST values can guide which patients are likely to recover function and potentially avoid unnecessary lifelong glucocorticoid replacement.