The MELD score has shown that, besides markers of liver function, serum
creatinine has a strong prognostic value in
cirrhosis. However, even though
creatinine has a good prognostic value, it is an inaccurate marker of renal function in
cirrhosis.
Creatinine and
creatinine-based equations tend to overestimate glomerular filtration rate (GFR), and
creatinine clearance from timed urine collection also overestimates GFR. Hence, clearance of exogenous markers such as
iohexol remains the only reliable method for assessing precisely GFR in
cirrhosis. Whereas these investigations are limited by their costs and complexity, and they can hardly be repeated at short intervals, serum
cystatin C could be an alternative, although it needs further validation. Accurate markers and/or specific equations are therefore still needed to assess GFR in cirrhotic patients. Pre-
renal failure and
hepatorenal syndrome (HRS) are the main causes of
acute renal failure in
cirrhosis. Both result from decreased renal blood flow and both can result in acute tubular
necrosis. HRS is not always fully reversible with
liver transplantation possibly due to underlying chronic kidney damage. A number of cirrhotic patients with
acute renal failure may also have chronic kidney damage ("acute-on-
chronic renal failure"); furthermore, cirrhotic patients frequently have co-morbidities such as diabetes that may result in chronic impairment in renal function. Since conventional urinary markers are biased in
cirrhosis, a biopsy is the only way to document and quantify renal lesions; moreover, transvenous route should be preferred to percutaneous route. In candidates for
transplantation, attention should therefore be focused on vascular lesions which may represent a risk factor for nephrotoxicities induced by
calcineurin-inhibitors.