Faecal Calprotectin

Calprotectin is a protein released by neutrophils — immune cells that flood into the bowel wall when it is inflamed. Measuring it in stool gives a direct, non-invasive read on whether there is genuine inflammation in the intestine.

Two very different conditions produce similar symptoms. Irritable bowel syndrome involves no inflammation and no tissue damage; inflammatory bowel disease involves both and can permanently damage the bowel if untreated. Faecal calprotectin distinguishes them, which means it determines whether someone needs a colonoscopy and biologic therapy — or dietary and gut–brain treatment. Few single tests change the path this decisively.

1. 1

   FoundationGut Health & The MicrobiomeWhat actually improves gut health — and why fibre beats the supplements people buy.
2. 2

   ConditionInflammatory Bowel DiseaseCrohn's disease and ulcerative colitis
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   Signal RecordProbioticsLive microorganisms taken for health benefit
4. 4

   Body SystemDigestiveGut health, the microbiome, and nutrient absorption.
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   BiomarkerHigh-Sensitivity CRPA marker of low-grade inflammation

1. Measure it
2. Understand your result
3. See what raises and lowers it
4. Apply evidence-based interventions
5. Recheck on your review cadence

An orientation to how this topic is typically approached — not medical advice.

A low calprotectin in someone with typical IBS symptoms and no alarm features is genuinely reassuring: it argues strongly against inflammatory bowel disease and can spare an unnecessary colonoscopy. A raised value is not a diagnosis in itself — it is a reason to look, with endoscopy and biopsy. In established IBD, serial calprotectin is used to monitor disease activity and detect relapse before symptoms escalate.

• Stool sample sent for faecal calprotectin
• Often paired with coeliac serology and full blood count

Faecal calprotectin is a well-validated, guideline-endorsed test for distinguishing inflammatory bowel disease from irritable bowel syndrome, and for monitoring disease activity in established IBD. Its main limitations are assay variability and its non-specificity: it detects inflammation without identifying the cause.

• NICE diagnostics guidance on faecal calprotectin testing
• ECCO and ACG guidance on IBD diagnosis and monitoring

Sources are named authoritative guidelines and scientific bodies. Biomarker pages present established clinical context; calibrated evidence verdicts on specific interventions live in the linked Signal Records.