GI Investigations · Patient Guide
Faecal Calprotectin: The Test That Helps Separate IBS from IBD
One stool sample, one question: is the bowel inflamed? The answer redirects the whole investigation.
Faecal calprotectin measures a protein released by inflammatory cells in the bowel wall. Its job is to answer a single, pivotal question: are these symptoms coming from an inflamed bowel (pointing towards conditions like Crohn's disease or ulcerative colitis) or a structurally normal one (pointing towards IBS)? Getting that fork in the road right early saves months.
How the result changes the pathway
A clearly normal calprotectin in a younger patient with typical IBS symptoms and no alarm features makes inflammatory bowel disease unlikely, and supports managing IBS confidently without scoping. A high result signals inflammation that needs direct assessment — usually colonoscopy with biopsies. Borderline results are commonly repeated, as infections and anti-inflammatory painkillers can nudge the number up.
When this test is usually indicated
- Younger patients with IBS-type symptoms, to decide who needs colonoscopy
- Distinguishing a flare of known IBD from IBS-type symptoms in the same patient
- Monitoring treatment response in established inflammatory bowel disease
- Persistent diarrhoea without red-flag features, as part of the initial work-up
When it may not be the right test
- Rectal bleeding, anaemia, weight loss or other alarm features — these warrant direct investigation regardless of the result
- Older patients with new bowel symptoms, where the priority is excluding structural disease
- As a cancer test — calprotectin measures inflammation, and bowel cancer can exist with a normal result
- During or just after a gut infection or a course of NSAIDs, when false positives are common
Calprotectin sorts inflammation from irritation — it does not exclude structural disease. In older patients or anyone with alarm features, colonoscopy remains the right move whatever the stool test says.
What happens if you do need it
If your calprotectin is raised, the next step is usually colonoscopy with biopsies to characterise the inflammation — which Mr Papettas performs as a JAG dual-accredited endoscopist, with histology reviewed and a management plan made with you. If IBD is confirmed, medical management is coordinated with gastroenterology colleagues, while any surgical aspects stay under one roof.
Frequently asked questions
What is a normal calprotectin level?
Laboratories typically use a threshold around 50 µg/g; below that is reassuring, clearly above it suggests inflammation, and borderline values are often re-tested.
Can IBS cause a raised calprotectin?
IBS itself doesn't inflame the bowel, so no — a genuinely raised result points away from IBS and towards something that needs looking at.
Can painkillers affect the result?
Yes — NSAIDs like ibuprofen can raise calprotectin, as can gut infections. That's why borderline results are repeated after a gap.
Does a normal calprotectin rule out bowel cancer?
No — it measures inflammation, not tumours. Alarm symptoms need direct assessment whatever the calprotectin shows.
How is the sample done?
A small stool sample in a pot, from home, returned to the lab — no preparation involved.
What happens if mine is high?
A consultation and usually a colonoscopy with biopsies to establish exactly what's inflaming the bowel — arranged within days privately. Call 01926 935121.
Related reading
Unsure whether you need this test?
Mr Trif Papettas FRCS is a Consultant Colorectal and General Surgeon at Nuffield Health Warwickshire Hospital, Leamington Spa, and a JAG dual-accredited endoscopist. A consultation settles which investigation, if any, your symptoms actually need — and if a test is indicated, it can usually be arranged within days.
Self-referrals welcome · No GP letter required · Self-pay and insured patients seen at Nuffield Health Warwickshire Hospital, Leamington Spa CV32 6RW