New diagnostic criteria for subclinical hypercortisolism using postsurgical hypocortisolism: the Co-work of Adrenal Research study.

Objective: There is no consensus on the biochemical diagnostic criteria for subclinical hypercortisolism (SH). Using parameters related to the hypothalamic-pituitary-adrenal axis, we aimed to develop a diagnostic model of SH for predicting postsurgical hypocortisolism and metabolic complications.

Methods: Prospective and cross-sectional, observational, multicentre study in Korea. Methods: After exclusion of overt Cushing's syndrome, adrenal incidentaloma (AI) patients who underwent unilateral adrenalectomy (n = 99) and AI patients (n = 843) were included. Primary outcome was defined as the presence of postsurgical hypocortisolism; secondary outcome was the presence of ≥4 complications (components of the metabolic syndrome and low bone mass). Postsurgical hypocortisolism was determined on the fifth postsurgery day using the ACTH stimulation test.

Results: Thirty-three of the 99 patients developed postsurgical hypocortisolism. Analysis of the presurgery overnight 1-mg dexamethasone suppression test (1-mg DST) showed that all patients with cortisol levels of >138 nmol/l experienced postsurgical hypocortisolism, whereas those with levels of ≤61 nmol/l did not. The models of (i) 1-mg DST >138 nmol/l or (ii) >61 nmol/l with the presence of one among low levels of ACTH and dehydroepiandrosterone-sulphate had the highest accuracy (89·9%, P < 0·001) and odds ratio [OR 111·62, 95% confidence interval (CI) 21·98-566·74, P < 0·001] for predicting postsurgical hypocortisolism. Finally, patients with the same criteria in the 843 AI patients showed the highest risk for having ≥4 complications (OR 3·51, 95% CI 1·84-6·69, P < 0·001), regardless of gender, age, body mass index and bilaterality.

Conclusions: Our proposed model is able to accurately predict subtle cortisol excess and its chronic manifestations in AI patients.