Leucine-Rich α2 Glycoprotein as a Predictor of Small Bowel Disease Activity in Crohn's Disease: A Retrospective Study

Balloon-assisted enteroscopy is the gold standard for evaluating small bowel lesions in Crohn's disease (CD); however, its invasiveness and cost limit routine use. Leucine-rich α-2 glycoprotein (LRG) has emerged as a potential noninvasive biomarker. This study aimed to assess the diagnostic utility of LRG compared with conventional biomarkers.

This retrospective study included 216 patients with CD who underwent balloon-assisted enteroscopy between April 2021 and March 2024. Serum biomarkers, including LRG, C-reactive protein, leukocyte count, neutrophil count, hemoglobin, platelet count, erythrocyte sedimentation rate, and albumin, were analyzed. Endoscopic activity was defined as mucosal ulcers measuring ≥0.5 cm. Diagnostic performance was evaluated using receiver operating characteristic curve analysis, and predictors of endoscopic activity were identified using multivariate logistic regression. Prognostic value was assessed using hospitalization-free and surgery-free survival.

LRG demonstrated the highest diagnostic accuracy (area under the ROC curve (AUC), 0.906), outperforming C-reactive protein ( area under the receiver operating characteristic curve: 0.776). An LRG cutoff of 16.3 μg/mL yielded 72.1% sensitivity and 93.7% specificity. Elevated LRG was independently associated with endoscopic activity (odds ratio: 36.4, p < 0.001) and correlated with higher modified Simple Endoscopic Score for Crohn's disease (mSES-CD). High LRG levels were also predictive of poorer hospitalization-free and surgery-free survival.

LRG is a reliable and non-invasive biomarker for assessing small bowel disease activity in CD, showing superior diagnostic and prognostic performance compared with conventional biomarkers. It may be a valuable adjunct to endoscopic and imaging evaluations in clinical practice.