Early assessment of postoperative adrenal function is necessary after adrenalectomy for mild autonomous cortisol secretion.

Abstract

The diagnostic threshold for mild autonomous cortisol secretion using low dose, overnight, dexamethasone suppression testing is recognized widely as a serum cortisol ≥1.8 mcg/dL. The degree to which these patients require postoperative glucocorticoid replacement is unknown. We reviewed adult patients with corticotropin (ACTH)-independent hypercortisolism who underwent unilateral laparoscopic adrenalectomy for benign disease with a dexamethasone suppression testing ≥1.8 mcg/dL at our institution from 1996 to 2018. Patients with a dexamethasone suppression testing of 1.8 to 5 mcg/dL were compared with those with a dexamethasone suppression testing >5 mcg/dL. We compared 68 patients with a preoperative dexamethasone suppression testing of 1.8 to 5 mcg/dL to 53 patients with a preoperative dexamethasone suppression testing >5 mcg/dL. Preoperative serum ACTH (mean 10.0 vs 9.2 pg/mL), adenoma size (mean 3.4 vs 3.5 cm), and side of adrenalectomy (37 and 47% right) were similar between groups (P > .05 each). Patients with a dexamethasone suppression testing 1.8 to 5 mcg/dL were older (mean values 58 ± 11 vs 52 ± 16 years ; P = .01), less likely to be female (63 vs 81%; P = .03), had greater body mass indexes (33.1 ± 8.4 vs 29.1 ± 5.6; P = .01), and had lesser 24 hour preoperative urine cortisol excretions (32.6 ± 26.7 vs 76.1 ± 129.4 mcg; P = .03). Postoperative serum cortisol levels were compared in 22 patients with a dexamethasone suppression testing of 1.8 to 5 mcg/dL to 14 patients with a dexamethasone suppression testing >5 mcg/dL. Those with dexamethasone suppression testing 1.8 to 5 mcg/dL had greater postoperative serum cortisol levels (8.0 ± 5.7 vs 5.0 ± 2.6 mcg/dL; P = .03), were less likely to be discharged on glucocorticoid replacement (59% vs 89%; P = .003), and had a decreased duration of treatment (4.4 ± 3.8 vs 10.7 ± 18.0 months; P = .04). Assessment of early postoperative adrenal function with mild autonomous cortisol secretion is necessary to minimize unnecessary glucocorticoid replacement.