Cholemic nephropathy causes acute kidney injury and is accompanied by loss of aquaporin 2 in collecting ducts

Abstract

Impairment of renal function often occurs in patients with liver disease. Hepatorenal syndrome is a significant cause of acute kidney injury (AKI) in cirrhotic patients (HRS‐AKI, type 1). Causes of non‐HRS AKI include cholemic nephropathy (CN), a disease that is characterized by intratubular bile casts and tubular injury. As data on patients with CN is mostly obtained from case reports or autopsy studies, we aimed to investigate the frequency and clinical course of CN. We identified 149 patients who underwent kidney biopsy between 2000 to 2016 at the Department of Gastroenterology, Hepatology and Endocrinology. Of these, 79 had a history of liver disease and deterioration of renal function. When applying recent EASL criteria 45 of the 79 patients (57%) presented with AKI, whereas 34 patients (43%) had chronic kidney disease (CKD) (43%). Renal biopsy revealed the diagnosis of CN in 8 of the 45 patients with AKI (17.8%), whereas none of the patients with CKD was diagnosed with CN. Univariate analysis identified serum bilirubin, alkaline phosphatase and urinary bilirubin and urobilinogen as predictive factors for the diagnosis of CN. Histological analysis of AKI patients with normal bilirubin, elevated bilirubin and the diagnosis of CN revealed loss aquaporin 2 (AQP2) expression in collecting ducts in patients with elevated bilirubin and CN. Biopsy related complications requiring medical intervention occurred in four of 79 patients (5.1%).

In conclusion, CN is a common finding in patients with liver disease, AKI and highly elevated bilirubin. Loss of AQP2 in AKI patients with elevated bilirubin and CN might be the result of toxic effects of cholestasis and be in part responsible for the impairment of renal function.

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