Quantitative and qualitative analyses of urinary L-FABP for predicting acute kidney injury after emergency laparotomy

The aim of this study was to explore the clinical utility of urinary L-FABP for earlier prediction of acute kidney injury (AKI) after emergency laparotomy, and to assess the clinical utility of a point-of-care (POC) kit for urinary L-FABP.

Forty-eight patients undergoing emergency laparotomy were divided into AKI and non-AKI groups by the kidney diseases: improving global outcome (KDIGO) criteria. Ten patients were included in the AKI group. Urinary L-FABP, albumin, N-acetyl-β-D-glucosaminidase (NAG), TIMP-2, IGFBP7, serum creatinine (SCr), and blood presepsin were measured perioperatively and compared between groups. Perioperative urinary L-FABP was also evaluated qualitatively using a POC kit.

L-FABP and albumin levels were significantly higher in the AKI group at all measurement points. NAG was significantly higher only postoperatively in the AKI group. There were no inter-group differences in [TIMP-2] × [IGFBP7] at any measuring point. The area under the receiver operating characteristic curve of urinary L-FABP was greater than 0.8 perioperatively, which was larger than that of other biomarkers throughout the study period. The correlation coefficient at 2 h after entering the operating room between quantitative and qualitative tests for urinary L-FABP was 0.714, which was the maximum. The sensitivity, specificity, and negative predictive value of the urinary L-FABP POC kit at 2 h after entry were 55.6%, 91.9%, and 89.5%, respectively.

Quantitative L-FABP analyses is suitable for predicting postoperative AKI earlier in the perioperative period of emergency laparotomy. Conversely, the higher specificity of qualitative L-FABP analysis suggests that it may be useful for excluding the risk of AKI but its overall clinical validity should be further investigated.