Is cystatin-c superior to creatinine in the early diagnosis of contrast-induced nephropathy?: a potential new biomarker for an old complication

Background/Aims: The aim of this study was to assess whether changes in Cystatin C (CyC) after 48 h post contrast media exposure was a reliable indicator of acute kidney injury and the validity of a risk scoring tool for contrast-induced acute kidney injury (CI-AKI). Materials and Methods: We enrolled 121 patients for whom diagnostic coronary angiography were planned. The risk score for CI-AKI was calculated and serum creatinine (sCr) and CyC were measured before and 48 h post coronary angiography. CyC and sCr based AKI was calculated as a 25% increase from baseline within 48 h from contrast media exposure. Results: Mean serum CyC and creatinine concentrations were 0.88 +/- 0.27 mg/dL and 0.79 +/- 0.22 mg/dL, respectively before the procedure and 1.07 +/- 0.47 mg/dL and 0.89 +/- 0.36 mg/dL, respectively 48 h after contrast media exposure (P < 0.001). CyC based AKI occured in 45 patients (37.19 %) and sCr based AKI occured in 20 patients (16.52%) after the procedure. Mean risk score was found to be 4.00 +/- 3.478 and 3.60 +/- 4.122 for CyC based AKI and sCr based AKI, respectively and was significantly increased in CyC based AKI group (P < 0.001). Conclusions: CyC measured 48 h after contrast media exposure may be a more sensitive indicator of CI-AKI relative to creatinine and Mehran risk scoring is in good correlation with CyC increase