Key facts
- What it is: a neutrophil protein that rises with intestinal inflammation.
- On the GI-MAP: reported as an intestinal-health marker with a quantitative value and reference range.
- Why it matters: helps distinguish inflammatory bowel disease (IBD) from functional problems like IBS.
- Method: measured by immunoassay (ELISA).
Calprotectin is a protein released by white blood cells (neutrophils) in the gut wall. When there is inflammation in the intestines, more neutrophils migrate into the gut and calprotectin rises in the stool, which is why it is measured on the GI-MAP (Gastrointestinal Microbial Assay Plus) as an intestinal-health marker.
Because it is non-invasive and reflects inflammation directly at the gut lining, calprotectin has become one of the most useful stool markers in clinical practice.
Why calprotectin matters
A large body of evidence supports faecal calprotectin as a sensitive, non-invasive screen for intestinal inflammation. A widely cited meta-analysis found it accurately screens adults with suspected inflammatory bowel disease and can reduce unnecessary endoscopies (PMID: 20634346).
A more recent systematic review with meta-analysis specifically evaluated calprotectin's ability to distinguish IBD from irritable bowel syndrome (IBS) in adults and found it a reliable test for separating the two (PMID: 37823411). That distinction matters because IBD and IBS can feel similar to a patient but are managed very differently.
How to read a calprotectin result
A normal calprotectin makes significant active intestinal inflammation less likely, while an elevated result signals that inflammation may be present and often prompts a clinician to investigate further. Calprotectin is not specific to one disease — infections, certain medications (such as NSAIDs), and other factors can raise it — so it is interpreted alongside symptoms and the rest of the GI-MAP panel.
Calprotectin does not diagnose any condition on its own. A raised value on a stool test is a prompt for clinical evaluation, not a diagnosis.
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- van Rheenen PF, Van de Vijver E, Fidler V. Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: diagnostic meta-analysis. BMJ. 2010;341:c3369. PMID: 20634346.
- Dajti E, Frazzoni L, Iascone V, et al. Systematic review with meta-analysis: diagnostic performance of faecal calprotectin in distinguishing inflammatory bowel disease from irritable bowel syndrome in adults. Aliment Pharmacol Ther. 2023;58(11–12):1120–1131. PMID: 37823411.