Accuracy of several parameters of hypothalamic–pituitary–adrenal axis activity in predicting before surgery the metabolic effects of the removal of an adrenal incidentaloma

CONTEXT: It is unknown whether the metabolic effects of the removal of an adrenal incidentaloma (AI) can be predicted by the assessment of cortisol hypersecretion before surgery. OBJECTIVE: To evaluate the accuracy of several criteria of hypothalamic-pituitary-adrenal axis activity in predicting the metabolic outcome after adrenalectomy. DESIGN: Retrospective longitudinal study. PATIENTS: In 55 surgically treated AI patients (Group 1) before surgery and in 53 nontreated AI patients (Group 2) at the baseline, urinary free cortisol (UFC), cortisol after 1 mg overnight dexamethasone-suppression test (1 mg-DST), ACTH, and midnight serum cortisol (MSC) were measured. In Groups 1 and 2, metabolic parameters were evaluated before and 29.6 ± 13.8 months after surgery and at the baseline and after 35.2 ± 10.9 months respectively. MAIN OUTCOME MEASURES: The improvement/worsening of weight, blood pressure, glucose, and cholesterol levels (endpoints) was defined by the presence of a >5% weight decrease/increase and following the European Society of Cardiology or the ATP III criteria respectively. The accuracy of UFC, 1 mg-DST, ACTH, and MSC, singularly taken or in combination, in predicting the improvement/worsening of ≥ 2 endpoints was calculated. RESULTS: The presence of ≥ 2 among UFC>70 μg/24 h (193 nmol/l), ACTH<10 pg/ml (2.2 pmol/l), 1 mg-DST>3.0 μg/dl (83 nmol/l) (UFC-ACTH-DST criterion) had the best accuracy in predicting the endpoints' improvement (sensitivity (SN) 65.2%, specificity (SP) 68.8%) after surgery. In the nontreated AI patients, this criterion predicted the worsening of ≥ 2 endpoints (SN 55.6%, SP 82.9%). CONCLUSIONS: The UFC-ACTH-DST criterion seems to be the best for predicting the metabolic outcome in surgically treated AI patients.