What Is Calprotectin?
Calprotectin is a protein released by white blood cells (neutrophils) in the gut when there is intestinal inflammation. Unlike blood CRP, faecal calprotectin directly reflects inflammation in the gut wall — making it highly useful for investigating inflammatory bowel disease (IBD).
Normal Calprotectin Range
| Level | Calprotectin (µg/g) | Interpretation |
|---|---|---|
| Normal | Below 50 | Gut inflammation unlikely — IBS or functional cause more likely |
| Borderline | 50–200 | Mild inflammation possible — retest or investigate further |
| Elevated | 200–600 | Significant intestinal inflammation — IBD likely |
| Highly elevated | Above 600 | Severe IBD inflammation or other serious gut pathology |
IBD vs IBS — The Key Use Case
IBD vs IBS
Crohn's disease and ulcerative colitis (IBD) cause measurable gut inflammation — calprotectin is elevated. IBS (irritable bowel syndrome) does not cause inflammation — calprotectin is normal. This makes calprotectin the best first test to separate the two.
What Else Can Cause High Calprotectin?
- NSAIDs (ibuprofen, aspirin) — can cause gut irritation and raise levels
- Gastrointestinal infections
- Bowel cancer or polyps
- Coeliac disease during gluten exposure
- Recent colonoscopy
Monitoring IBD
Once an IBD diagnosis is established, calprotectin is used to monitor disease activity and treatment response — a declining level suggests effective treatment and mucosal healing.
FAQs
How is the test collected?
A small stool sample is placed in a collection vial and sent to the lab. No bowel prep or fasting required.
Can calprotectin replace colonoscopy?
No — it indicates whether further investigation is needed. A colonoscopy with biopsy remains the definitive diagnostic tool.
Does age affect normal levels?
Yes — calprotectin is naturally higher in children under 4. Adult reference ranges apply from around age 4 onwards.
Medical Disclaimer: An elevated calprotectin warrants further investigation by a gastroenterologist. It is not a standalone diagnostic test.