Fecal calprotectin: assessment of a rapid test

Background. Calprotectin, a protein found mainly in neutrophil granulocytes, is used as an inflammatory marker, while the fecal concentration of the protein is used to detect gastrointestinal (GI) inflammation. Material and methods. Fecal calprotectin in 100 stool samples was measured by the ELISA method and by a new rapid test. Eighty-two patients had fecal calprotectin measured for clinical reasons and delivered 95 stool samples. The rest were delivered by healthy volunteers. Results. The association between the two tests was statistically significant (p < 0.0001, chi(2) test). With calprotectin values < 15 mu g/g, the sensitivity and specificity of the new rapid test was 96% (95% confidence interval (CI), 87-100 %) and 70 % (CI, 55-83 %), respectively, with a negative predictive value of 94 % (CI, 81-99 %). With values > 15 mu g/g, the rapid test was less accurate, thus rendering results in this range difficult to interpret. Conclusions. The new rapid test is useful as a screening test for excluding GI inflammation when the cut-off of 15 mu g/g is used. With fecal calprotectin concentrations > 15 mu g/g, the rapid test should be supplemented by quantitative measurement.