Correlation of Fecal, Plasma, Serum, and Salivary Calprotectin to Endoscopic and Histologic Outcomes in Patients With Crohn’s Disease

Easily obtained, noninvasive biomarkers are needed for Crohn’s disease monitoring. This pilot study compared associations between calprotectin levels in stool, saliva, and blood to assess their correlation with endoscopic and histologic outcomes among patients with Crohn’s disease. Participants recruited from an Inflammatory Bowel Disease center provided stool, blood, and saliva samples prior to undergoing scheduled colonoscopy (n = 17). We collected participant demographics and clinical disease activity. Endoscopic disease was assessed with the Simple Endoscopic Score. Histologic disease was assessed with the Robarts Histological Index. The mean age of the sample was 32.3 (SD 7.5) years. Correlations with endoscopic disease activity were 0.83 for fecal calprotectin, 0.26 for plasma calprotectin, 0.24 for serum calprotectin, and 0.02 for salivary calprotectin. Correlations with histologic disease activity were 0.80 for fecal calprotectin, 0.55 for plasma calprotectin, 0.15 for serum calprotectin, and −0.03 for salivary calprotectin. Fecal calprotectin had the strongest correlations with endoscopic and histologic disease outcomes, but fecal calprotectin levels were lower among those with ileal disease. For blood-based calprotectin, plasma calprotectin had a higher correlation with histology than serum, and plasma calprotectin levels were higher among those with ileal disease.