Serum Leucine-Rich α2 Glycoprotein: A Biomarker for Predicting the Presence of Ulcerative Colitis but Not Ulcerative Proctitis

The serum level of leucine-rich α2 glycoprotein (LRG) is a biomarker for active ulcerative colitis (UC). We examined the serum level of LRG as a biomarker for predicting the presence of UC. Patients with persistent diarrhea and/or bloody stool with no history of UC were consecutively enrolled at their initial visit. Serum LRG measurement and colonoscopy with histology were performed on the same day. We enrolled 103 patients (69 men; median age, 45 years) with suspected UC; 66 patients were diagnosed with active UC (proctitis, n = 10; left-sided colitis, n = 26; and pancolitis, n = 30) based on endoscopic and histological criteria. Although the median LRG value in patients with proctitis was similar to that of patients with normal colonoscopic findings (8.5 vs. 8.6 mg/mL, p = 0.24), the median LRG values were significantly elevated in patients with left-sided colitis and pancolitis compared with those of patients with normal colonoscopy (13.6 or 18.0 vs. 8.6 mg/mL, p < 0.0001). The LRG cut-off value of 10.8 μg/mL was derived from the ROC curve, showing 96% sensitivity and 97% specificity for active UC but not active proctitis. Using a cut-off value of 10.8 mg/mL serum, LRG could be a novel biomarker for predicting patients with active UC except for proctitis.