Pathogenesis and assessment of renal function in patients with liver cirrhosis

In liver cirrhosis patients awaiting liver transplantation, it is prognostically equally important to assess the renal function before and after transplantation. This is evidenced by the inclusion of serum creatinine in the Model for End-Stage Liver Disease (MELD) score. Most of the causes of renal failure in liver cirrhosis are functional, the acute kidney damage including prerenal azotemia, acute tubular necrosis and hepatorenal syndrome. A major index of the renal function, the glomerular filtration rate (GFR) is determined in a specific way in patients with liver cirrhosis. Clinically, serum creatinine is considered the best indicator of kidney function, although it is rather unreliable when it comes to early assessment of renal dysfunction. Most of the patients with liver cirrhosis have several concomitant conditions, which are the reason for the false low creatinine levels, even in the presence of moderate to severe kidney damage. This also holds for the creatinine clearance and creatinine-based estimation equations for assessment of the glomerular filtration rate (the Cockroft-Gault and MDRD formulas), which overestimate the real glomerular filtration. Clearance of exogenous markers is considered a gold standard, but the methods for their determination are rather costly and hard to apply. Alternative serum markers (e.g., cystatin C) have been used, but they should be better studied in cases of liver cirrhosis assessment.