Faecal Calprotectin

Calprotectin is a heat stable protein, which is resistant to bacterial degradation, found within the granules of the commonest inflammatory cell called a neutrophil. Most neutrophils only survive in the body for a few hours before releasing their granules into the surrounding tissues.  Therefore if a part of the gut is inflamed for any reason calprotectin is released into the gut’s lumen (The passage where food and digestive juices are digested and converted into stool). The levels of calprotectin can then be measured in the stool and this gives a useful marker for detecting or monitoring disease. Whilst it is an incredibly sensitive test for detecting the presence of inflammation,  it is raised in a wide variety of conditions including malignancy, inflammatory bowel disease and alcohol misuse and  it is therefore not good at defining either the site or the cause of inflammation.

 

Usually a positive calprotectin leads to further investigation. However it is not uncommon for slightly elevated levels to have no clear cause even after extensive investigation, for this reason many experts do not encourage “over investigation” in patients with levels of less than 200mg/g.