Post-surgical hypocortisolism after removal of an adrenal incidentaloma: is it predictable by an accurate endocrinological work-up before surgery?

OBJECTIVE: Few data are available regarding the need of steroid substitutive therapy after unilateral adrenalectomy for adrenal incidentaloma (AI). It is unknown whether, before surgery, the hypothalamic-pituitary-adrenal (HPA) axis secretion parameters can predict post-surgical hypocortisolism. AIM: This study aimed to evaluate whether, in AI patients undergoing unilateral adrenalectomy, post-surgical hypocortisolism could be predicted by the parameters of HPA axis function.
DESIGN: Prospective, multicenter.
METHODS: A total of 60 patients underwent surgical removal of AI (surgical indication: 29 subclinical hypercortisolism (SH); 31 AI dimension). Before surgery, SH was diagnosed in patients presenting at least three criteria out of urinary free cortisol (UFC) levels>60 microg/24 h, cortisol after 1-mg dexamethasone suppression test (1 mg-DST)>3.0 microg/dl, ACTH levels<10 pg/ml, midnight serum cortisol (MSC)>5.4 microg/dl. Two months after surgery, HPA axis function was assessed by low dose ACTH stimulation test or insulin tolerance test when needed: 39 patients were affected (Group B) and 21 were not affected (Group A) with hypocortisolism. The accuracy in predicting hypocortisolism of pre-surgical HPA axis parameters or their combinations was evaluated.
RESULTS: The presence of >2 alterations among 1 mg-DST>5.0 microg/dl, ACTH<10 pg/ml, elevated UFC and MSC has the highest odds ratio (OR) for predicting post-surgical hypocortisolism (OR 10.45, 95% confidence interval, CI 2.54-42.95, P=0.001). Post-surgical hypocortisolism was predicted with 100% probability by elevated UFC plus MSC levels, but not ruled out even in the presence of the normality of all HPA axis parameters.
CONCLUSION: Post-surgical hypocortisolism cannot be pre-surgically ruled out. A steroid substitutive therapy is indicated after unilateral adrenalectomy for SH or size of the adenoma.