Urinary liver-type fatty acid-binding protein level as a predictive biomarker of contrast-induced acute kidney injury

Background Contrast-induced acute kidney injury (CI-AKI) is a well-known complication of contrast medium exposure in patients with chronic kidney disease. However, there are no biological markers to accurately predict the onset of CI-AKI. Liver-type fatty acid-binding protein (L-FABP), an intracellular carrier protein for free fatty acids, is markedly upregulated and abundantly expressed in the proximal tubules after renal ischaemia. We prospectively investigated whether urinary L-FABP is a suitable marker for the prediction of CI-AKI. Methods We performed a prospective study of 220 consecutive patients with chronic kidney disease who underwent elective catheterization [serum creatinine (Cr) = 1.2 mg/dL (106 M)]. Serum Cr and L-FABP levels were measured immediately before and 1 and 2 days after the procedure. CI-AKI was defined as an increase in serum Cr level of = 0.3 mg/dL within 48 h after the procedure. Results We observed the development of CI-AKI in 19 patients (8.6%). Urinary L-FABP levels were significantly higher in patients with CI-AKI than those without CI-AKI before contrast medium exposure. Receiver operating characteristic analysis showed that baseline urinary L-FABP level exhibited 82% sensitivity and 69% specificity, at a cut-off value of 24.5 mu g/g Cr. Using multivariate analysis, we found that independent predictors of CI-AKI development were L-FABP level of = 24.5 mu g/g Cr [odds ratio (OR): 9.10; 95% confidence interval (CI), 3.2028.9], and left ventricular ejection fraction = 40% (OR, 3.42; 95% CI, 1.0710.8). Conclusions Urinary L-FABP level is useful for predicting the onset of CI-AKI before contrast medium exposure.