Role of leucine-rich α-2-glycoprotein in Taiwanese patients with inflammatory bowel disease as a predictive biomarker for endoscopic activity

BACKGROUND Endoscopy is the gold standard for examining inflammatory bowel disease (IBD), and fecal calprotectin (FC) is a widely used surrogate marker for IBD. However, both methods are considered unpleasant by patients because of their invasiveness and inconvenience. Leucine-rich α-2-glycoprotein (LRG) is a novel serum biomarker that has been previously studied only in Japanese populations. AIM To evaluate the predictive utility of LRG in a Taiwanese cohort. METHODS Patients with IBD were prospectively enrolled between 2022 and 2024. Serum and stool samples were collected within 1 month of endoscopy, and patient albumin, hemoglobin (Hb), and C-reactive protein (CRP) levels were measured. Active endoscopic disease was defined as a Mayo endoscopic subscore ≥ 2 for ulcerative colitis (UC) or a Simple Endoscopic Score for Crohn’s Disease ≥ 6 for Crohn’s disease (CD). Correlations and diagnostic performance of biomarkers were analyzed. RESULTS A total of 203 patients (100 with UC and 103 with CD) were enrolled. LRG was positively correlated with FC and CRP but negatively correlated with Hb and albumin (P < 0.05). In UC, the area under the curves (AUCs) for CRP, LRG, and FC in predicting endoscopic activity were 0.54, 0.56, and 0.77, respectively (P < 0.001). In CD, the corresponding AUCs were 0.69, 0.60, and 0.72 (P > 0.05). The addition of LRG modestly improved predictive ability for endoscopic activity in patients with UC. In patients with UC with low CRP levels, combining CRP, Hb, and LRG significantly improved diagnostic accuracy (AUC increased from 0.60 to 0.76, P < 0.05), achieving a performance comparable to, though slightly lower than, that of FC (AUC: 0.78). CONCLUSION LRG may serve as a supportive biomarker, particularly in combination with other markers, for assessing disease activity in Taiwanese patients with IBD. In patients with UC with normal CRP levels, adding LRG and Hb could enhance the predictive accuracy for endoscopic activity to nearly that of FC.