Calprotectin is a 36 kDa protein which is universally found in the body. The "protein" belongs to the S 100 protein family with two 14 kDa (MRP14, S100 A9) and one 8 kDa (MRP8, S100 A8) chain of amino acids. The protein is expressed during myeloid differentiation, are abundant in neutrophil granulocytes and monocytes. Myeloid cells, which are developed in the bone marrow, migrates in large amounts into the blood and further into tissues in many diseases and conditions, like cystic fibrosis, rheumatoid arthritis and many inflammations and malignant diseases.

Calprotectin is a very abundant neutrophil protein with many "characteristics"
It constitutes more than 60% of total proteins in the cytosol of neutrophil granulocytes, each neutrophil contains 25 picograms of calprotectin compared to about 30 picograms haemoglobin per erythrocyte.

Calprotectin is released from activated leukocytes leading to concentrations in plasma, serum, spinal fluid, synovial fluid, urine, saliva or stools is increased during bacterial infections or inflammation in relevant organs.

Calprotectin is antimicrobial and has induced apoptosis in all cell types (human, animal, normal, malignant) tested. These effects can be reversed by addition of zinc. By binding zinc calprotectin can inhibit many important metalloproteinases.
Lack of calprotectin is not compatible with life.


The Calprotectin syndrome presents with a clinical picture suggestive of zinc deficiency: children/young adults show growth retardation, bone marrow depression, immune deficiency, hepatosplenomegaly, arthritis and vasculitis; the concentration of calprotectin in their plasma is 2000 to 12000 times the normal. These huge amounts of calprotectin bind so much zinc that a functional zinc deficiency is created.

Calprotectin as a disease marker:

  1. To obtain representative blood values of calprotectin it is recommended to collect blood samples on EDTA; the concentration in serum is generally higher with more variations. Substantial amounts of calprotectin are released during coagulation.
    Body fluids: Increased concentrations will be found in response to infections and inflammation. Plasma calprotectin levels reflect disease activity in rheumatoid arthritis and LED better than ESR and CRP.
  2. Stool samples: The CalproLab, Calprotectin ELISA test or CalproSmart for determination of faecal calprotectin concentrations has become a routine objective and non-invasive assay for detection of gastrointestinal inflammation or neoplasia and for assessment of inflammatory bowel disease activity and response to treatment. It can also predict the risk of relapse in patients in clinical remission; a normal quatitative calprotectin value is evidence that mucosal healing has been achieved. Use of the calprotectin assessement assists in selecting patients for endoscopy, in particular among children needing general anaesthesia.


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General Information

Fecal calprotectin in differential diagnosis of irritable bowel syndrome

Li XG, Lv YM, Gu F, Yang XL., Department of Gastroenterology, Peking University Third May 9, 2015

Latest News

Calpro press release regarding MSD agreement

Please see the Calpro press release regarding MDS agreement for delivery of e-health technology CalproSmart:

Norsk | English October 13, 2016

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