Urinary excretion of liver-type fatty acid-binding protein reflects the severity of sepsis

Sepsis due to microbial invasion often causes multiple organ failure (MOF), including acute kidney injury (AKI), with high mortality rates in serious cases. Hence, there is an urgent need for diagnostic biomarkers that can be used to rapidly, accurately, and easily detect sepsis to identify the condition early and guide the selection of appropriate treatment. Liver-type fatty acid-binding protein (L-FABP), which localizes in renal proximal tubules, is excreted into the urine in response to oxidative stress-induced tubular injury. Because of this mechanism, L-FABP has been reported to be a useful urinary biomarker not only for renal disease but also for the severity of sepsis. Based on this concept, we developed a new L-FABP point-of-care (POC) assay kit that can be used to rapidly measure human L-FABP in the urine to further improve the usefulness of this biomarker in clinical settings. In this review, we describe the molecular mechanisms of L-FABP, its clinical usefulness, and the performance of the POC assay kit.