Defining renal failure in cirrhosis -Acute kidney injury classification or traditional criteria?

Bile Cast Nephropathy in Cirrhotic Patients: Effects of Chronic Hyperbilirubinemia

OBJECTIVES

The aim of this study was to determine the prevalence of bile cast nephropathy (BCN) in autopsied cirrhotic patients and to correlate BCN with clinical and laboratory data to direct attention to this underrecognized renal complication of liver failure.

METHODS

We assessed 114 autopsy cases of cirrhosis for the presence of renal intratubular bile casts using Hall stain for bile. Presence of bile casts was correlated with etiology of cirrhosis, clinical and laboratory data, and histologic findings.

RESULTS

Bile casts were identified in 55% of cases. The most common etiology of cirrhosis was hepatitis C virus (HCV) infection (52%), and serum creatinine ( P  = .02) and serum urea nitrogen ( P  = .01) were significantly higher in the Hall-positive group. Conjugated bilirubin was below 20 mg/dL in 90%, and levels below 10 mg/dL were noted in 80% of cases.

CONCLUSIONS

To our knowledge, this is the largest study of BCN in human subjects and a first report describing the association of BCN with HCV-related cirrhosis. We demonstrated that in the face of protracted chronic hyperbilirubinemia, bile casts are formed at much lower bilirubin levels than previously thought. Furthermore, we proposed an algorithm to assist in better identification of bile casts.

The evolving concept of acute kidney injury in patients with cirrhosis

Renal dysfunction is prevalent in patients with advanced cirrhosis and decompensation. The presence of type 1 hepatorenal syndrome (HRS) has traditionally been defined by a set of stringent criteria based on serum creatinine levels. These diagnostic criteria have been found to be too stringent to be widely applicable to patients with cirrhosis, leading to underdiagnosis of renal failure in this population. Acute kidney injury (AKI) has now been proposed to characterize renal dysfunction in patients with cirrhosis and is defined as an increase in serum creatinine by 0.3 mg/dl in <48 h or an increase in serum creatinine by 50% from a stable baseline reading within 3 months. Type 1 HRS is renamed HRS-AKI. Stage 1 AKI is defined by 0.3 mg/dl serum creatinine or a 50% increase, stages 2 and 3 AKI are defined by a two-fold and three-fold increase in serum creatinine levels, respectively. Data collected so far suggests that even stage 1 AKI is associated with worse prognosis in patients with cirrhosis. The progression of AKI usually indicates substantially worse outcomes. A panel of biomarkers, including inflammatory markers, are envisaged to complement and enhance our current diagnostic criteria in the future and provide aetiology of the AKI.