Aim: To compare serum creatinine (SCr) and serum cystatin C as early marker of acute kidney dysfunction.

Methodology: The present cross sectional observation study consisted of eighty- four ICU admitted patients (critical ill). A randomization of patients into 2 groups was done. Patients with normal kidney functions were put in group 1 while those with impaired kidney functions were in group 2. The estimation of serum creatinine (SCr) and serum cystatin C was done. Mann Whitney U and ch- square test was used for statistical inference.

Results: In group 1 patients, mean serum creatinine (SCr) was 0.30± 0.21 mg/dl and in group 2 was 0.56±0.41 mg/dl. Serum cystatin C level in group 1patients found to be 0.42±0.17 mg/l and 1.5±0.68 mg/l in group 2 patients. Accuracy for Cys- C was better than SCr (90% vs 67%). Specificity for SCr was 97% whereas for Cys- C was 95%. Sensitivity for Cys-C was 80% while for SCr was 25%. SCr had PPV of 92% and NPV of 61% and for Cys- C it was 93% and 83% respectively.

Conclusion: Serum cystatin C found to be better than serum creatinine for the identification of impairment of kidney functions in critically ill patients. Hence, assessment of Cys-C is of great concern in AKI.

Key words: Acute renal failure, serum creatinine, serum, renal impairment