Calprotectin in the stool

Markers of intestinal inflammatory activity

Clinical signs of a bowel function disorder such as diarrhoea, cramps, pain and bloating can have various causes. These include functional complaints (irritable bowel syndrome), viral and bacteria-related infections and non-infectious, usually chronic inflammatory diseases such as ulcerative colitis or Crohn’s disease.

While infectious causes can be identified by detecting the pathogens in acute cases, the only possible way to distinguish between functional and chronic inflammatory changes until recently was by means of arduous invasive procedures such as a colonoscopy and histology.
With the introduction of calprotectin, there is now a valid non-invasive laboratory diagnostic marker for the differential diagnostic distinction between functional and chronic inflammatory and neoplastic changes in the bowel.

In the S3 guidelines „Irritable Bowel Syndrome” and „Diagnosis and Treatment of Crohn’s Disease”, calprotectin in the stool is therefore recommended as a significant marker for differential diagnostics and currently the best laboratory diagnostic marker.

In particular, calprotectin, a protein from the group of calcium and zinc-binding S100 proteins, is released by polymorphonuclear granulocytes. It accounts for approximately 60 % of the cytosolic proteins of neutrophil granulocytes. In a lower concentration, calprotectin is also formed by monocytes and activated macrophages.

When there is a disruption in the barrier function of the intestinal mucosa due to inflammatory and neoplastic intestinal diseases, increased numbers of neutrophil granulocytes triggered by chemotaxis pass through the wall of the intestine into the intestinal lumen and release calprotectin. This can then be detected in an increased concentration in the stool. Here, the calprotectin concentration correlates with the number of the infiltrating granulocytes in the intestine and thus reflects the activity of the inflammatory and/or neoplastic process.
As an activity marker, therefore, calprotectin is also well suited for evaluating therapeutic success and for early detection of relapses.

Indications
Calprotectin detection in the stool is thus used for

  • differentiating between inflammatory and functional intestinal diseases
  • ruling out irritable bowel syndrome
  • suspected cases of chronic inflammatory bowel disease (ulcerative colitis, Crohn’s disease, diverticulitis)
  • assessing inflammatory activity in chronic inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease (surges in activity)
  • Therapy monitoring for chronic inflammatory intestinal diseases and early detection of periods of remission and relapses

Interpretation
In primary diagnostics, increased calprotectin values justify suspicions of an inflammatory bowel disease and thus the need for further differential diagnostic clarification, such as by means of invasive procedures like a colonoscopy and/or microbiological or laboratory testing procedures (including the detection of haemoglobin / haptoglobin complexes in the stool and M2 pyruvate kinase in the stool). Primarily normal calprotectin values, however, indicate that the patient’s gastrointestinal symptoms are caused by irritable bowel syndrome.

Material

A bean-sized stool sample, taken from the first stool of the day where possible (stability of the calprotectin in a native stool sample lasts for approximately 7 days; for long-term storage, it is recommended that the stool be frozen at -20 °C)

Please note!
Avoid contamination with water from the toilet (disinfectant!)
Before collecting the sample, there is no need for the patient to follow any special diet.

Method
ELISA (enzyme immunoassay

Reference range
The valid limit value for older children and adults is currently 50 mg/kg.
Healthy people usually exhibit values of around 10 mg/kg.

To top

Back