BACKGROUND: Contrast-induced nephropathy is acute kidney injury caused by contrast medium exposure. Serum creatinine is the clinical diagnostic standard, but it does not yield quick results. The serum level of cystatin C is stable and it can reflect renal function sensitively. The study aimed to assess the usefulness of cystatin C for early diagnosis of contrast-induced nephropathy in patients undergoing coronary angiography.

MATERIAL AND METHODS: We included 300 patients who underwent CAG. According to the sCr at 48 h, patients were divided into 2 groups: CIN group and non-CIN group. Their demographics and basal renal function were recorded. Changes in sCr, Cys C, and e GFR were compared at the same time. ROC analysis was used to assess the sensitivity and specificity of Cys C in the early diagnosis of CIN.

RESULTS: Comparison of basal renal function and serum level of Cys C showed no significant differences between the 2 groups. Serum level of Cys C increased significantly at 24 h (p<0.001), and sCr increased significantly at 48 h. ROC analysis showed that the AUC of the change in Cys C between baseline and 24 h was 0.936 (95% CI: 0.879–0.992, p=0.000) and the optimum cut-off level was 0.26 mg/L (sensitivity=89.7% and specificity=95.6%).

CONCLUSIONS: The concentration change of Cys C is better than sCr as a biomarker in the early detection of CIN.

Keywords: Contrast Media - adverse effects, Coronary Angiography, Creatinine - blood, Cystatin C - blood, Early Diagnosis, Kidney Diseases - diagnosis, ROC Curve