Faecal calprotectin for the diagnosis of inflammatory bowel disease

For the family doctor presented with a patient who gives a short history of bloody diarrhoea the clinical diagnosis of ulcerative colitis may be straightforward, particularly if there is a family history of inflammatory bowel disease or recent cessation of smoking. However, making a diagnosis of Crohn’s disease can be challenging, especially in younger patients, when symptoms of recurrent abdominal pain and intermittent diarrhoea may be indistinguishable from those of irritable bowel syndrome (a more likely diagnosis). Referral to specialist services for diagnosis usually involves either colonoscopy or flexible sigmoidoscopy, which may be uncomfortable for patients with irritable bowel syndrome who have visceral hypersensitivity. The linked meta-analysis by van Rheenen and colleagues (doi:10.1136/bmj.c3369) highlights a new approach to the diagnosis of inflammatory bowel disease that might reduce the number of patients referred for endoscopy.1

Calprotectin is a non-covalently associated complex of two S100 (A8 and A9) proteins that is released from phagocytes and inflamed epithelia as part of the initial innate immune response. It is resistant to intestinal degradation and is distributed throughout the …