Fecal Calprotectin as a Biomarker for Disease Activity in Microscopic Colitis

Background: Microscopic colitis (MC) is an intestinal inflammatory disorder. An objective biomarker to assess ongoing disease activity has not been previously examined. We aimed to examine the utility of fecal calprotectin (FC) measurement in symptomatic individuals with microscopic colitis. Methods: This cohort study included patients with a confirmed diagnosis of MC who had a calprotectin level measured in the setting of ongoing symptoms. We examined the frequency of elevation of FC in the setting of symptomatic microscopic colitis. Univariate and multivariate logistic regression models examined the independent predictors of elevated FC levels. Results: Our study included a total of 166 subjects, yielding 234 independent instances of FC measurement during symptomatic MC. Of all 234 FC measurements, 68 (29.0%) levels were >150 mcg/g and 43 (18.4%) FC level>250 mcg/g. Those with elevated FC levels>150 mcg/g were older than those below this cutoff (54.7 vs. 61.5 y, P =0.011, respectively). A higher fraction of those with elevated FC (> 150 mcg/g) had nocturnal bowel movements (41.2 vs. 24.1%, P =0.009) and fecal incontinence (25.0 vs. 13.3%, P =0.029) compared with those with normal FC levels. This association was further evidenced on multivariate analysis. There was no difference in FC levels between those who were responsive or refractory to steroids (138 mcg/g vs. 249 mcg/g, P =0.45). Conclusions: Elevated calprotectin concentrations were noted in over a quarter of patients with symptomatic microscopic colitis and were associated with more severe symptoms. However, FC levels did not indicate the likelihood of treatment response.