Clinical Application of Kidney Biomarkers in Cirrhosis.

Acute kidney injury (AKI) is one of the most common and morbid complications of decompensated cirrhosis. Management of AKI is dictated by cause: prerenal AKI is treated with volume resuscitation; hepatorenal syndrome (HRS), with intravenous albumin and vasoconstrictors; and acute tubular necrosis, with supportive care. However, differentiating between causes is difficult using creatinine-based definitions of AKI alone. The use of novel kidney biomarkers in AKI and cirrhosis provides an opportunity to improve both the diagnosis and prognosis of this vulnerable population. This review examines the challenges of AKI in cirrhosis and the research experience around novel kidney biomarkers in cirrhosis. Specific focus is paid to the tubular injury marker neutrophil gelatinase-associated lipocalin (NGAL), which has been the most studied in liver disease and has demonstrated the strongest performance in differentiating the cause of AKI (acute tubular necrosis vs functional injury such as prerenal AKI or HRS), as well as improving the prognostic performance of mortality prediction models such as the model for end stage liver disease (MELD) score. We advocate for the discussion of incorporating markers such as NGAL in the next iteration of HRS guidelines and identify areas for future research in this clinical condition.