Fecal calprotectin levels predict colorectal inflammation among patients with chronic diarrhea referred for colonoscopy

OBJECTIVE: Chronic diarrhea is a relatively common condition with multiple diverse etiologies. Stool testing may serve as a diagnostic aid to discrimi nate the presence or absence of organic pathology, such as colorectal infla mmation. Calprotectin (a leukocyte-derived protein) and hemoglobin can be m easured quantitatively from stool and represent candidate inflammation biom arkers. The aim of this study was to assess and compare the screening perfo rmance of fecal calprotectin and fecal hemoglobin among colonoscopy referra l patients with chronic diarrhea of unknown origin or chronic colitis of un known activity. METHODS: All subjects were identified prospectively and each submitted a si ngle stool sample before purgation. Fecal calprotectin (PhiCal; Nycomed Pha rma, Oslo, Norway) and fecal hemoglobin (HemoQuant; Mayo Medical Laboratori es, Rochester, MN) assays were performed in separate laboratories by masked technicians. Colonoscopic and histological findings served as criterion st andards for establishing the presence or absence of colorectal inflammation . RESULTS: Among 110 subjects who provided complete fecal assay data, 29 (26% ) had and 81 (74%) did not have colorectal inflammation. Increased fecal ca lprotectin levels were significantly (p = 0.0001) associated with the prese nce of colorectal inflammation, whereas fecal hemoglobin levels were not (p = 0.61). Direct comparison of the fecal assays revealed that calprotectin was a more sensitive biomarker for colorectal inflammation at all specifici ty levels (p = 0.0001). CONCLUSIONS: In this study of colonoscopy referral patients, colorectal inf lammation was reflected by fecal calprotectin but not by fecal hemoglobin l evels. Assay of fecal calprotectin holds promise as a triage tool to identi fy inflammatory causes of chronic diarrhea. (Am J Gastroenterol 2000; 95:28 31-2837. (C) 2000 by Am. Coll. of Gastroenterology).