Faecal calprotectin
A test done on a stool sample that measures inflammation in the bowel. It is most useful for telling inflammatory bowel disease (Crohn's, ulcerative colitis) apart from irritable bowel syndrome, and for tracking how active known bowel inflammation is.
What it measures
Calprotectin is a protein released by neutrophils — a type of white blood cell — when there is inflammation. When the lining of the bowel is inflamed, these white cells move into the gut and shed calprotectin, which passes out in the stool, so measuring it in a stool sample gives a direct, non-invasive readout of inflammation in the intestine. This is despite the schema listing it as a blood test — it is done on a stool (faecal) sample, not blood. Its main value is in sorting out gut symptoms. Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD — Crohn's disease and ulcerative colitis) can cause similar symptoms of abdominal pain, bloating and altered bowel habit, but IBS does not inflame the bowel while IBD does. A normal calprotectin makes IBD unlikely and points towards IBS, helping people avoid an unnecessary colonoscopy; a raised level flags inflammation that needs investigation, usually with endoscopy. It is also used to monitor known IBD — following the level shows whether the disease is active or in remission and whether treatment is working — and it can rise with gut infections and some medications too.
What a high value can mean
- Inflammatory bowel disease (Crohn's or ulcerative colitis) — the main concern; a raised level flags active bowel inflammation needing endoscopy.
- Active disease or a flare in known IBD — a rising level suggests the disease is not controlled.
- Gut infection (gastroenteritis) — a temporary rise.
- NSAID painkillers — can cause bowel inflammation and raise it.
- Bowel polyps or, rarely, tumours — occasionally raised.
What a low value can mean
- Normal — makes inflammatory bowel disease unlikely and points towards irritable bowel syndrome, often sparing an invasive test.
- A falling level in known IBD — suggests the inflammation is settling and treatment is working (remission).
When to discuss with a doctor
Faecal calprotectin is most useful when the question is whether ongoing bowel symptoms — persistent diarrhoea, abdominal pain, altered habit — come from inflammation (IBD) or from a non-inflammatory cause such as irritable bowel syndrome. A normal result is reassuring and can avoid an unnecessary colonoscopy; a clearly raised result points to inflammation that needs investigating, usually with endoscopy. In someone with known Crohn's or ulcerative colitis, the level is followed to judge disease activity and response to treatment. Because infections and some painkillers can raise it, the result is read with the clinical picture. Any raised calprotectin, or alarm features such as bleeding, weight loss or anaemia, should be discussed promptly. Mediora.AI shows calprotectin alongside CRP, blood count and albumin so the inflammation pattern is visible; the interpretation belongs with your doctor.