Fecal calprotectin: a marker for clinical differentiation of microscopic colitis and irritable bowel syndrome

BACKGROUND The aim of this study is to compare two methods for measuring fecal calprotectin (FC) concentration and to evaluate the possibility of differentiation between microscopic colitis (MC) and irritable bowel syndrome (IBS). METHODS Twenty-three patients with MC (six patients with active disease and 17 patients retested in remission) and 20 patients with IBS were prospectively included in this study. Active disease state of MC was determined by clinical symptoms of >3 bowel movements per day and histological correlate. All patients underwent ileocolonoscopy, including segmental biopsy samples for histology. FC levels in stool samples were analyzed using a rapid test system (Quantum Blue(®)) and an enzyme-linked immunosorbent assay (ELISA). RESULTS FC levels were significantly higher in patients with active MC (median 48 μg/g [23-106]) compared to patients with IBS (median 2 μg/g [1-111.83]), P=0.0001 using an ELISA. FC level of patients with MC in remission was 22 μg/g (1-106.4), which is similar to those identified in patients with IBS. The difference of FC levels between active MC and IBS was not detected by the FC rapid test (P=0.635). DISCUSSION FC levels might serve as parameter for differentiation between patients with active MC and IBS. Since there is no surrogate marker available at present for MC, FC appears to be a candidate for differentiating MC from IBS. CONCLUSION High FC levels, which were analyzed by ELISA, are a potential marker for patients with active MC compared to those with IBS. The FC rapid test was less suitable for this purpose.