Masked renal dysfunction in patients with adrenal Cushing’s syndrome manifested by adrenalectomy

INTRODUCTION AND OBJECTIVES

Many patients with primary aldosteronism (PA) exhibit a decline in renal function after adrenalectomy. Excessive aldosterone secretion causes glomerular hyperfiltration, and cancellation of this excessive secretion manifests the masked renal dysfunction. Considering the mineralocorticoid effect of cortisol as with aldosterone, excessive cortisol secretion may also mask the renal dysfunction of patients with adrenal Cushing’s syndrome (CS). However, postoperative changes in renal function in patients with CS have not been evaluated. We evaluated changes in renal function after adrenalectomy in patients with functional adrenal tumor.

METHODS

A total of 164 consecutive patients underwent adrenalectomy for unilateral functional adrenal tumor at our institution between January 2004 and October 2014. Of the 164 patients, we retrospectively analyzed 118 patients (PA/CS/subclinical Cushing’s syndrome [SCS]/pheochromocytoma [PCC]: n = 51/21/13/33, respectively) who were followed up for over 6 months and whose change in renal function was evaluable. Laboratory data, including baseline hormone levels before medical treatment, were collected from medical records. Estimated glomerular filtration rate (eGFR) values were obtained using the 3-variable Japanese equation. Renal dysfunction was defined as a 20% reduction in eGFR from baseline to within 3 times average during the 6 months post-operation. The change in eGFR before and after the operation was analyzed in each adrenal tumor.

RESULTS

The mean change in eGFR before and after the operation was -14% (range, -55%-18%) in patients with PA, -9% (-48%-23%) in patients with CS, -2% in patients with SCS, and -2% in patients with PCC. The eGFR decline in patients with PA and CS was significant (p < 0.0001 and p = 0.0171, respectively), while there was no significant change in patients with SCS and PCC. After the operation, 39% (20/51) and 24% (5/21) of patients with PA and CS manifested renal dysfunction, respectively, while none of the patients with SCS and PCC manifested renal dysfunction. Preoperative renal function was not correlated with manifested renal dysfunction. Multivariate analysis identified older age and higher levels of plasma aldosterone concentration as independent predictors of renal dysfunction manifestation in patients with PA, while no clinical predictor was identified in patients with CS.

CONCLUSIONS

This is the first report that has shown a decline in eGFR after adrenalectomy in patients with CS. Possible masked renal damage should be considered in patients with CS as well as PA.

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