Postoperative renal impairment and longitudinal change in renal function after adrenalectomy in patients with Cushing's syndrome

Objectives: To evaluate the renal function after adrenalectomy in patients with Cushing's syndrome in comparison with that in patients with primary aldosteronism. Methods: This retrospective study included 35 patients with Cushing's syndrome and 51 patients with primary aldosteronism who underwent unilateral adrenalectomy and were followed up for >6 months. The renal function was analyzed before and after adrenalectomy using the estimated glomerular filtration rate. Postoperative renal impairment was defined as a >25% reduction in the estimated glomerular filtration rate from baseline at 1 month after adrenalectomy. Multivariate logistic regression analyses were carried out to examine whether the differences between Cushing's syndrome and primary aldosteronism increased the risk of postoperative renal impairment. Longitudinal changes were calculated starting 1 month after adrenalectomy using the linear mixed model. Results: The mean estimated glomerular filtration rate in both groups significantly decreased at 1 month after adrenalectomy from baseline. Postoperative renal impairment was observed in four (11%) and 12 (24%) patients in the Cushing's syndrome and primary aldosteronism groups, respectively. Multivariate analysis showed that preoperative systolic blood pressure was independently associated with postoperative renal impairment, but not with the type of the disease. There was no significant increase or decrease in postoperative estimated glomerular filtration rate observed after the initial decrease after adrenalectomy in either group. Conclusions: Patients with Cushing's syndrome show the same persistent renal impairment after adrenalectomy as that reported in patients with primary aldosteronism. Attention should be given to possible masked renal damage in clinical practice for the management of Cushing's syndrome.