The faecal calprotectin test has a relatively high specificity and sensitivity (approximately 90%) for distinguishing between non-inflammatory bowel disorders (e.g. irritable bowel syndrome) and inflammatory bowel disease (IBD) examples of which include ulcerative colitis and Crohn’s disease. Calprotectin will also be elevated in some cases of GI tract malignancy (e.g. colorectal cancer). Calprotectin is regularly raised in active IBD. Faecal Calprotectin concentrations relate well to disease activity in the inflammatory bowel diseases and can therefore be used to monitor therapy. There is a strong positive correlation between faecal calprotectin concentration and faecal excretion of 111Indium labeled granulocytes which is the suggested gold standard technique in monitoring Crohn’s disease.
Calprotectin is a stable protein that accounts for about 60% of neutrophil cytosolic protein. Lower concentrations are found in monocytes and reactive macrophages. Calprotectin is released into the faeces when neutrophils gather at the site of any gastrointestinal (GI) tract inflammation. Calprotectin can provide a non-invasive, inexpensive and objective method for assessing patients for additional possible invasive procedures e.g. colonoscopy or imaging studies.
- Initial calprotectin <100ug/g: Likely IBS.
- Initial calprotectin >100ug/g: Please repeat within 2 weeks.
- Repeat calprotectin <100ug/g: Likely IBS.
- Repeat calprotectin 100-250ug/g: IBD possible; routine referral.
- Repeat calprotectin >250ug/g: IBD likely; urgent referral.
Adapted from the York Care Pathway; for use in primary care
Stool samples should be collected into universal plain containers without any additives.