Faecal markers of gastrointestinal inflammation.

Gastrointestinal (GI) symptoms including abdominal pain, bloating and diarrhoea are a relatively common reason for consulting a physician. They may be due to inflammatory bowel disease (inflammatory bowel disease; Crohn's disease, ulcerative colitis and indeterminate colitis), malignancy (colorectal cancer), infectious colitis or irritable bowel syndrome (IBS). Differentiation between these involves the use of clinical, radiological, endoscopic and serological techniques, which are invasive or involve exposure to radiation. Serological markers include C-reactive protein, erythrocyte sedimentation rate and antibodies (perinuclear antineutrophil cytoplasm antibody and anti-Saccharomyces cerevisiae antibody). Faecal markers that can aid in distinguishing inflammatory disorders from non-inflammatory conditions are non-invasive and generally acceptable to the patient. As IBS accounts for up to 50% of cases presenting to the GI clinic and is a diagnosis of exclusion (Rome III criteria), any test that can reliably distinguish IBS from organic disease could speed diagnosis and reduce endoscopy waiting times. Faecal calprotectin, lactoferrin, M2-PK and S100A12 will be reviewed.