['The goals of treating ulcerative colitis (UC) have shifted from clinical remission to mucosal healing. Non-invasive biomarkers are required to assess mucosal healing as endoscopic assessment is inconvenient for patients. Enhanced expression of trefoil factor 3 (TFF3, a mucin-associated peptide) is observed after injury of the gastrointestinal tract. The present study was designed to evaluate TFF3 as a biomarker of mucosal healing in patients with UC.', 'This cross-sectional study included consecutive patients with UC (18-65 years old, disease duration >3 months, either left-sided colitis or pancolitis) who had a Simple Clinical Colitis Activity Index (SCCAI) <6. Colonoscopy was done to assess the presence or absence of mucosal healing (defined using the Baron score) in all patients. Serum level of TFF3 was assessed in all patients and 20 healthy controls.', 'Seventy-four patients were included [mean age 37.2±10.9 years, 47 males, median disease duration 4.8 years (IQR 3-8.3), median SCCAI = 0] in the study. Forty-three patients had mucosal healing (Baron score 0 or 1) and 31 did not (Baron score 2 or 3). Median TFF3 level in patients without mucosal healing was significantly higher than that in patients with mucosal healing [1.5 (IQR 1.2-1.9) vs 1.1 (IQR 0.8-1.3) ng/ml, p = 0.01] and healthy controls [0.85 (IQR 0.7-1.2) ng/ml, p < 0.001]. A serum TFF3 level of <1.27 ng/ml (as determined by the receiver operating characteristic curve; area under the curve 0.73) had sensitivity, specificity, positive predictive value and negative predictive value of 70, 68, 75 and 62%, respectively, for identifying patients with mucosal healing.'] Is serum human trefoil factor 3 a biomarker for mucosal healing in ulcerative colitis patients with minimal disease activity?