Calprotectin

Calprotectin is a calcium and zinc-binding protein. It is predominantly found in cells that are involved in the defence against pathogens. For example in neutrophil granulocytes in which calprotectin makes up 60% of the cytosolic protein. In the event of inflammation in the intestinal tract, neutrophil granulocytes migrate through the intestinal wall into the intestinal lumen. This leads to increased calprotectin in the stool.

The determination of faecal calprotectin is a non-invasive test to clearly differentiate between CED and RDS or other functional disorders. The test has proven to be the non-invasive method with the highest sensitivity and specificity for this differentiation and is clearly superior to blood tests such as CRP or BSG. Further studies have demonstrated the superiority or at least equivalence of calprotectin over lactoferrin in both the differentiation of CED and RDS and the differential diagnosis of acute diarrhea, with the concentration of faecal calprotectin directly correlating with the number of neutrophil granulocytes in the intestinal lumen.

The indications are:

• Initial diagnosis of CED (ulcerative colitis, Crohn's disease, diverticulitis), exclusion of purely functional complaints
• Monitoring of inflammatory activity in CED, also under therapy
• Monitoring of remissions
• Early detection of recurrence

The cut-off for differentiating functional complaints from CED remains at 50 µg/g stool. Healthy adults (and children aged 4 years and older) usually have significantly lower concentrations.

• < 50 µg/g: an inflammatory event is practically excluded
• 50-200 µg/g: grey area: mild inflammatory changes (e.g. chronic intake of NSAIDs, diverticulosis), control or clarification according to clinic
• > 200 µg/g: active inflammation of the GI tract; if confirmed from 2nd decrease: immediate further clarification indicated

Send in an approximately hazelnut-sized stool sample (1 ml), preferably from the first stool of the day in a stool tube (stability of calprotectin in a native stool sample at room temperature for approx. 3 days).

1. Manceau H et al(2017) Fecal calprotectin in inflammatory bowel diseases: update and perspectives. Clin Chem Lab Med 55:474-483.