Faecal calprotectin: a marker of inflammation throughout the intestinal tract.

Only a small proportion of patients with abdominal discomfort have organic disease, but a correct diagnosis can seldom be made by simple clinical examination. Additional diagnostic procedures must be employed, but these are expensive and demanding and carry a certain risk. Assessment of faecal concentrations of the neutrophil granulocyte-derived protein calprotectin can be used as a screening test--an 'ESR of the gut'--to select patients for further examination. The test can be performed on 1-2 g of random stool samples that can be sent to the laboratory by ordinary mail since the protein is remarkably stable in stools. The test has high sensitivities and specificities for gastrointestinal cancers and inflammatory bowel disease (IBD). Faecal calprotectin levels reflect the disease activity in IBD and can be used to monitor the response to treatment and detect relapses.