Fecal leukocyte esterase levels predict endoscopic severity as an alternative biomarker in inflammatory bowel disease

Abstract Objectives Our previous study revealed a correlation between fecal leukocyte esterase and fecal calprotectin levels. This study assessed the predictive value of fecal leukocyte esterase compared with fecal calprotectin and C-reactive protein of inflammatory bowel disease. Methods Patients with inflammatory bowel disease who underwent ileocolonoscopy at National Taiwan University Hospital from March 2022 to March 2024 were included. Fecal leukocyte esterase and fecal calprotectin levels from stool samples collected within one month of endoscopy were analyzed. Active ulcerative colitis and Crohn’s disease were defined as Mayo endoscopic score ≥2 or simple endoscopic score for Crohn’s disease ≥7, respectively. Sensitivity, specificity, predictive values, and areas under the receiver operating characteristic curve were calculated using IBM SPSS Statistics 29. Results Of the 203 patients (100 with ulcerative colitis and 103 with Crohn’s disease), fecal leukocyte esterase levels were significantly correlated with fecal calprotectin levels (r=0.425, p<0.001) and endoscopic severity in ulcerative colitis (r=0.432, p<0.001) and Crohn’s disease (r=0.311, p=0.001). For predicting Mayo endoscopic scores ≥2 in ulcerative colitis using fecal leukocyte esterase, fecal calprotectin, and C-reactive protein, areas under the curve were 0.731, 0.785, and 0.558, respectively. For predicting simple endoscopic scores for Crohn’s disease ≥7, areas under the curve were 0.706, 0.800, and 0.770, respectively. No significant difference was observed between fecal leukocyte esterase and fecal calprotectin. Conclusions Fecal leukocyte esterase correlates with fecal calprotectin and predicts endoscopic severity in inflammatory bowel disease.