Home » Top Tips » Medical Conditions » Gastrointestinal » What is a FCP (Faecal Calprotectin) Test? 
Andy Stein
May 18, 2026

What is a FCP (Faecal Calprotectin) Test? 

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What is a FCP (Faecal Calprotectin) Test? 

  • An FCP (Faecal Calprotectin) test is a non-invasive stool test that measures levels of calprotectin, a protein released into the intestines when there is inflammation.
  • It is primarily used to help doctors distinguish between inflammatory bowel diseases (IBD) like Crohn’s and ulcerative colitis, and non-inflammatory conditions like irritable bowel syndrome (IBS).

Why is the test done?

Doctors typically request an FCP test if a patient is experiencing long-term gastrointestinal symptoms—such as abdominal pain, cramping, or persistent diarrhoea—and the cause is unclear.

Because symptoms of IBD and IBS are very similar, the FCP test serves as a crucial screening tool: 
  • Normal/Low Levels: Usually suggests a functional disorder like IBS.
  • High Levels: Strongly indicates inflammation in the gut, meaning further hospital investigations (like an endoscopy or colonoscopy) may be required to get a precise diagnosis.

Common FCP Levels and Interpretation

  • < 50-100 mcg/g: Normal; IBD is unlikely, often indicative of IBS.
  • 100-250 mcg/g: Mildly elevated; often warrants repeat testing or clinical review.
  • > 250 mcg/g: Significantly elevated; likely indicates active inflammation/IBD

Monitoring Existing Conditions

For patients who have already been diagnosed with IBD, the FCP test is highly valuable for:
  • Assessing disease activity: Checking how severe the inflammation currently is.
  • Monitoring treatment: Seeing if medication is successfully reducing inflammation in the bowel. 

How it works

The test is very straightforward and can be completed at home: 
  1. You collect a small stool sample in a provided container.
  2. You return the sample to your GP or a hospital laboratory for testing.
  3. It is generally advised to avoid taking Non-Steroidal Anti-Inflammatory Drugs (NSAIDs like ibuprofen or naproxen) for about 4 weeks prior to the test, as they can cause a false positive by irritating the gut. 

Other Resources

To learn more about what specific numbers mean or how to interpret your results, you can check the Cleveland Clinic Guide on Fecal Calprotectin or refer to the MedlinePlus Calprotectin Stool Test for a comprehensive medical overview.

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