Predictive value of serum cystatin C, β₂-microglobulin, and urinary liver-type fatty acid-binding protein on the development of contrast-induced nephropathy

Contrast-induced nephropathy (CIN) is associated with prolonged hospitalization and adverse clinical outcomes. Useful predictors of CIN are necessary to minimize the risk of developing CIN. The purpose of this study was to identify the useful predictors of CIN. We prospectively measured serum cystatin C (CysC) and β₂-microglobulin (β₂-MG), and urinary liver-type fatty acid-binding protein (L-FABP), β₂-MG and N-acetyl-β-d-glucosaminidase (NAG) before and 1 day after percutaneous coronary intervention (PCI) in 96 patients with stable angina who underwent elective PCI. The frequency of CIN was 5% (5/96). Baseline levels of serum β₂-MG (4.2 ± 2.6 vs. 2.2 ± 1.0 mg/L, p = 0.0007) and CysC (1.51 ± 0.52 vs. 1.11 ± 0.34 mg/L, p = 0.013) were significantly higher in the CIN group. Urinary β₂-MG, NAG, and L-FABP levels became significantly elevated after PCI. Of these, the mean change of urinary L-FABP was significantly higher in the CIN group (25.2 ± 31.5 vs. 8.9 ± 16.3 ng/mL, p = 0.044). Univariate linear regression analyses showed that the change of urinary L-FABP correlated positively with the volume of contrast medium (r = 0.460, p < 0.0001). Receiver-operating characteristic analysis showed that baseline serum β₂-MG exhibited 75% sensitivity and 80% specificity at a cut-off point of >2.8 mg/L, and baseline serum CysC exhibited 75% sensitivity and 73% at a cut-off point of >1.26 mg/L for predicting CIN. In conclusion, baseline serum β₂-MG and CysC were useful predictors of CIN. The change of urinary L-FABP serves as an indicator of renal injury due to contrast medium and as an adjunct predictor of CIN.