Intestinal fatty acid-binding protein is a biomarker for diagnosis of biliary tract infection

Background and Aim: Biliary tract infection (BTI) is an inflammatory disease and commonly associated with bacteremia. Delays in diagnosis or treatment of BTI cause high morbidity and mortality. However, an early diagnosis depends on appropriate clinical investigations. Appropriate biomarkers are urgently needed to improve the BTI diagnostic rate. We hypothesized that intestinal fatty acid-binding protein (I-FABP) might be a potential biomarker for BTI diagnosis. Methods: We examined data from subjects aged ≥18 years diagnosed with BTI, including cholangitis and cholecystitis, whose blood samples were adequate for I-FABP and zonulin assessment. We also collected blood samples from healthy volunteers as the control group. We excluded subjects in both groups who received steroids, antibiotics, or probiotics within 1 month before hospital admission (BTI cohort) or participation in this research (controls). The main study endpoint was to compare the diagnostic ability of I-FABP to detect BTI in comparison with high-sensitivity C-reactive protein (hs-CRP) and zonulin. Results: The study collected the data of 51 patients with BTI and 35 healthy subjects. The receiver operating characteristic (ROC) area under the curve (AUC) for I-FABP was 0.884 (95% confidence interval [CI]: 0.814–0.954), numerically higher than that for hs-CRP (0.880; 0.785–0.976) and zonulin (0.570; 0.444–0.697). We estimated that the optimal cutoff value of I-FABP was 2.1 ng/mL (sensitivity: 0.804; specificity: 0.829) for the diagnosis of BTI. Conclusions: In summary, this study suggests that I-FABP may be a potential alternative biomarker to hs-CRP for diagnosing BTI. Further research should verify the use of I-FABP as a marker for BTI diagnosis, but also for other inflammatory diseases.