Objective: The utility of fecal calprotectin (fCal) in small bowel Crohn's disease (CD) remains to be clarified. The primary aim of this study was to determine levels of fCal in CD restricted to the small bowel compared with CD affecting the colon, in patients undergoing their first diagnostic work-up. In addition, the study assessed the sensitivity and specificity of fCal in suspected CD.
Material and methods: A total of 83 patients referred to gastroenterology out-patient clinic with suspected CD were included in this prospective, blinded study, and fCal was measured during diagnostic work-up. Ileo-colonoscopy + capsule endoscopy/surgery (n = 81), ileo-colonoscopy + upper endoscopy (n = 1), and ileo-colonoscopy (n = 1) served as gold standard for the presence and location of CD.
Results: A total of 40 patients were diagnosed with CD: small bowel 13, colonic 16, and ileo-colonic 11. Levels of fCal were equal in patients with small bowel or colonic CD: median 890 mg/kg and 830 mg/kg, respectively (p = 1.0). With a 50 mg/kg cut-off, CD in the small intestine and colon was diagnosed with 92% and 94% sensitivities, respectively, and the overall sensitivity and specificity of fCal was 95% and 56%. In this cohort, CD was ruled out with a negative predictive value of 92%.
Conclusions: This is the first study to show that fCal is equally sensitive in colonic and small bowel CD. In patients suspected of CD, fCal is an effective marker to rule out this diagnosis and select patients for endoscopy.