Myeloperoxidase Luminol Reaction – A Novel Faecal Assay for Predicting Colonoscopy Findings in Patients with Ulcerative Colitis: A Pilot Cross‐Sectional Clinical Study

Abstract Inflammatory Bowel Disease (IBD), including ulcerative colitis (UC), requires non‐invasive, convenient and cost‐effective biomarkers for disease monitoring. Myeloperoxidase (MPO), a neutrophil‐derived enzyme, correlates with intestinal inflammation. This study aims to assess the Myeloperoxidase Luminol Reaction (MPOLR) assay – a novel chemiluminescent‐based method for detecting faecal MPO (fMPO) activity, to improve the prediction of endoscopic findings in UC. A cross‐sectional clinical study recruited 39 participants, categorized into UC (n = 20), colonoscopy control (CC; n = 9), and healthy control (HC; n = 10). Faecal samples are analysed for fMPO, calprotectin (fCalpro), and lactoferrin (fLacto) using ELISA and the MPOLR assay. The MPOLR assay is validated against endoscopic disease severity (UCEIS), symptomology, and clinical indices. MPOLR strongly correlated with UCEIS (ρ = 0.78), disease severity (ρ = 0.75), and symptomology (ρ = 0.78), outperforming fCalpro (ρ = 0.58, ρ = 0.57, and ρ = 0.41, respectively). AUROC analysis reveals MPOLR (0.78) and fMPO (0.75) have superior predictive potential for UC diagnosis compared to fCalpro (0.66). MPOLR is a rapid, cost‐effective assay that enhances UC monitoring by accurately reflecting endoscopic findings and outcompetes fCalpro and other faecal biomarkers’ predictive potential for UC diagnosis.