Faecal Calprotectin
This is a stool test that picks up inflammation in your gut. Its main job is to help your doctor tell whether ongoing gut symptoms come from real inflammation in the bowel (the kind seen in Crohn's and colitis) or from a non-inflammatory cause like irritable bowel syndrome. The two can feel very similar but are managed quite differently, so telling them apart matters.
Standard CareWhat is faecal calprotectin?
Calprotectin is a protein released by neutrophils — a type of white blood cell — when they gather at a site of inflammation. When the lining of the bowel is inflamed, neutrophils move into the gut and release calprotectin, which then passes into the stool. A faecal (stool) calprotectin test measures how much is there, giving an indirect read on how much inflammation is present in the intestines: the level of calprotectin correlates with the level of inflammation. Because it specifically reflects inflammation in the bowel, faecal calprotectin is mainly used to help separate two groups of conditions that can cause similar symptoms: inflammatory bowel disease (IBD) — which includes Crohn's disease and ulcerative colitis, where the bowel is genuinely inflamed — and irritable bowel syndrome (IBS), a common condition that causes real symptoms but without that inflammation. The two are easily confused, yet they are quite different. It is a non-invasive test (a stool sample rather than a procedure), which is part of why it is useful as an early step before deciding whether someone needs a colonoscopy.
Why is it tested?
Faecal calprotectin is usually ordered when someone has persistent gut symptoms — such as ongoing diarrhoea, abdominal pain, or changes in bowel habit — and the question is whether there is inflammation in the bowel. Its main value is in helping to filter people with a higher probability of inflammatory bowel disease from the larger group whose symptoms are mainly due to irritable bowel syndrome, so that the right people are referred for further assessment (such as a colonoscopy) and others are spared an invasive test they may not need. It can also be used in people already diagnosed with IBD to help monitor how active the inflammation is over time, alongside their specialist's assessment.
Reference range (Australia)
The cut-off that separates a normal from a raised faecal calprotectin varies by laboratory and assay, and results near the threshold are often interpreted with care or repeated. The reference cut-off printed on your own report is the correct one to use for your result.
Reference intervals vary between laboratories. Always use the range printed on your own report.
What your result means
A low (normal) faecal calprotectin makes significant bowel inflammation, and therefore active inflammatory bowel disease, less likely. In someone with gut symptoms, this is one of the findings that points more towards a non-inflammatory cause such as irritable bowel syndrome, and can help avoid an unnecessary colonoscopy. A low result does not explain what is causing your symptoms — it mainly helps rule inflammation out. If your symptoms persist, that is still worth discussing with your GP. A normal result tells your GP about inflammation only, and does not rule out every bowel condition on its own. So if you have symptoms that worry you, like bleeding, unintended weight loss or a persistent change in your bowel habit, those are worth raising with your GP regardless of this number.
A result within the normal range on your report suggests little or no inflammation in the bowel at the time of the test. Read alongside your symptoms, this is generally reassuring about an inflammatory cause — though your GP will still consider the whole picture, since symptoms can have causes that this test does not measure.
A raised faecal calprotectin suggests there is inflammation in the bowel, because more calprotectin is released when neutrophils gather at inflamed gut lining. A higher level points to a higher chance that an inflammatory condition — rather than a non-inflammatory one like IBS — is behind the symptoms, and usually prompts further assessment such as referral for a colonoscopy. A raised result is not a diagnosis on its own. Infections and some medicines (for example regular anti-inflammatory painkillers) can also raise calprotectin. Your GP will read the result alongside your symptoms and history and decide on the right next step, which is often specialist referral.
What can affect your result
Faecal calprotectin reflects inflammation in the gut, so anything that inflames the bowel lining can raise it — not only inflammatory bowel disease. Gut infections (bacterial or viral) can raise calprotectin temporarily, which is one reason a raised result is interpreted in context and sometimes repeated once an infection has settled. Some medicines can lift it — regular non-steroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen) can irritate the gut lining and raise calprotectin. Sampling can matter: because the test is done on a stool sample, results near the cut-off are sometimes rechecked. Your GP interprets the number alongside your symptoms rather than treating a single value as definitive.
When to act
If your faecal calprotectin is raised, your GP will consider your symptoms and history and, in many cases, refer you to a gastroenterologist for further assessment such as a colonoscopy, since a raised result increases the likelihood of an inflammatory bowel condition. A raised result soon after a gut infection, or while taking regular anti-inflammatory painkillers, may be rechecked. If your result is normal and your symptoms fit a non-inflammatory pattern, your GP may focus on managing the symptoms (for example, those of irritable bowel syndrome) rather than proceeding straight to a colonoscopy — though persistent or changing symptoms are always worth reviewing. This page is general information and is not a substitute for advice from your GP.
Frequently asked questions
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