Capabilities of fecal calprotectin and blood biomarkers as surrogate endoscopic markers according to ulcerative colitis disease type.

Fecal calprotectin level in ulcerative colitis patients is correlated with endoscopic findings. However, its association with various ulcerative colitis disease types has not been elucidated. In the present study, we investigated the correlation of fecal calprotectin level with endoscopic findings as compared to blood biomarkers according to ulcerative colitis disease type. Fecal calprotectin as well as the blood biomarkers: C-reactive protein (CRP), white blood count (WBC), erythrocyte sedimentation rate (ESR), hemoglobin, platelet count (PLT), and serum albumin (Alb) were measured in patients who underwent a complete colonoscopy. Disease type was divided into proctitis, left-sided colitis, and extensive colitis. Correlations of fecal calprotectin and blood biomarker levels with Mayo endoscopic subscore were analyzed. A total of 186 colonoscopy examinations were performed in 124 patients with ulcerative colitis. Fecal calprotectin level showed a significant correlation with Mayo endoscopic subscore regardless of disease type (proctitis, r = 0.54, <0.01; left-sided colitis, r = 0.75, <0.01; extensive colitis, r = 0.78, <0.01), and clearly discriminated inactive (Mayo endoscopic subscore 0) from active stages (Mayo endoscopic subscore 1-3). On the other hand, none of the examined blood biomarkers showed a correlation with Mayo endoscopic subscore in the proctitis group, while weak correlations of several biomarkers (CRP, WBC, ESR, PLT and Alb) with Mayo endoscopic subscore were found in left-sided colitis and extensive colitis cases. This is the first report to elucidate the capabilities of fecal calprotectin and blood biomarkers as endoscopic surrogate markers according to ulcerative colitis disease type.