LIMITATIONS OF SERUM CREATININE LEVEL AND CREATININE CLEARANCE AS FILTRATION MARKERS IN CIRRHOSIS

Background: Several studies carried out in a limited number of patients demonstrated a wide range of overestimation of glomerular filtration rate (GFR) by serum creatinine level and creatinine clearance (C-cr) in liver disease. Methods: We simultaneously evaluated C-cr, inulin clearance, and predicted GFR calculated from serum creatinine level in 56 cirrhotic patients. Inulin clearance was considered the gold standard for GFR evaluation. Results: The sensitivity of serum creatinine level, predicted GFR, and C-cr in detecting renal failure was 18.5%, 51%, and 74%, respectively. On the basis of inulin clearance, patients were divided into two groups: those with normal GFR (mean, 106 +/- 34 mL/min per 1.73 m(2)) (group 1, 29 patients) and those with reduced GFR (mean, 56 +/- 19 mL/min per 1.73 m(2)) (group 2, 27 patients). Predicted GFR and C-cr were accurate markers of GFR in group 1 patients, while both overestimated GFR by about 50% in group 2 patients. An increased tubular secretion of creatinine accounted for the disparity between C-cr and inulin clearance in these patients. Conclusions: Our results indicate that renal failure is greatly underestimated on the basis of serum creatinine level and C-cr in cirrhotic patients. Clinical implications of this observation include excessive dosage of potentially nephrotoxic drugs and failure to recognize renal impairment induced by such medical treatments as diuretic therapy or paracentesis.