Adrenalectomy in Japanese patients with subclinical Cushing syndrome: 1-mg dexamethasone suppression test to predict the surgical benefit

Objectives: To investigate whether the result of the 1-mg dexamethasone suppression test can predict the improvement of comorbidities after adrenalectomy in patients with subclinical Cushing syndrome. Methods: This retrospective study included 117 subclinical Cushing syndrome patients who underwent adrenalectomy. The numbers of prescribed drugs for metabolic comorbidities and the clinical variables at diagnosis were compared with those at the follow up. Patients were classified into subgroups according to the result of the 1-mg dexamethasone suppression test. Results: Significant improvements in blood pressure, serum cholesterol and body mass index were observed. Furthermore, a significant improvement in glycated hemoglobin was observed in patients with diabetes mellitus. These improvements led to a discontinuation or reduction of prescribed drugs after surgery. In addition, the greatest reduction of prescribed drugs was observed in patients whose serum cortisol levels were between 1.8 and 3.0 mu g/dL after the 1-mg dexamethasone suppression test. Conclusions: The result of the 1-mg dexamethasone suppression test can be a useful factor predicting the improvement of comorbidities after adrenalectomy. Current data might give us a new insight into the decision-making for the treatment of subclinical Cushing syndrome.