Defining Nonfunctioning Adrenal Adenomas on the Basis of the Occurrence of Hypocortisolism after Adrenalectomy.

Abstract

BackgroundIn patients with adrenal incidentalomas (AIs), there is uncertainty on how to rule out hypercortisolism. The occurrence of postsurgical (unilateral adrenalectomy) hypocortisolism (PSH) has been proposed as a proof of the presence of presurgical hypercortisolism in AI patients. The aim of this study was to define the thresholds of cortisol level after the 1 mg overnight dexamethasone suppression test (F-1mgDST), urinary free cortisol (UFC), midnight serum cortisol (MSC), and adrenocorticotropin (ACTH) to predict the absence of PSH in AI patients undergoing surgery.MethodsIn 60 patients who underwent AI excision, cortisol secretion was assessed by a low-dose corticotropin stimulation test or insulin tolerance test when needed. We searched for the lowest presurgical value of F-1mgDST, UFC, and MSC and the highest value for ACTH in AI patients with PSH as indexes of normal cortisol secretion.ResultsThe lowest values of F-1mgDST, UFC, and MSC and the highest value for ACTH in PSH patients were 1.2 µg/dL (33 nmol/L), 10.4 µg/24 hours (29 nmol/24 hours), 1.2 µg/dL (33 nmol/L), and 26.9 pg/mL (6 pmol/L), respectively, but only F-1mgDST <1.2 µg/dL (33 nmol/L) was able to predict the absence of PSH. Among AI patients with F-1mgDST <1.2 µg/dL (33 nmol/L) no subjects had diabetes mellitus and/or metabolic syndrome, and these subjects tended to have a better metabolic profile than those with F-1mgDST ≥1.2 µg/dL (33 nmol/L)ConclusionIn AI patients a F-1mgDST <1.2 µg/dL (33 nmol/L) rules out PSH and could be used to exclude hypercortisolism in AI patients.