Finding the right tests…
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Finding the right tests…
ELISA
Calprotectin is a protein released by white blood cells called neutrophils whenever your gut lining is inflamed. This test measures how much of it shows up in a stool sample, which is why no needle or blood draw is involved. Doctors order it most often when someone has ongoing diarrhoea, cramping, or blood in the stool, to work out whether the cause is inflammatory bowel disease - Crohn's disease or ulcerative colitis - or a non-inflammatory condition like irritable bowel syndrome, which does not raise calprotectin. A high result does not confirm IBD by itself; it flags gut inflammation that usually needs an endoscopy to explain.
The result is reported in micrograms of calprotectin per gram of stool, checked against the lab's cutoff for what counts as raised. A large review found this cutoff correctly flags around 97 out of 100 people who truly have inflammatory bowel disease, though it also comes back raised in many people who turn out to have irritable bowel syndrome instead - so a raised result alone isn't proof of IBD. A result within the normal range makes IBD considerably less likely, which is why doctors use this test to help decide who needs a colonoscopy, not to replace one.
Neutrophils, a type of white blood cell, move into the gut wall whenever it's inflamed and release calprotectin into the intestine as they do. The protein survives well in stool, which is why testing a stool sample - rather than blood - works, and why the result stays fairly stable even if the sample sits for a day or two before reaching the lab.
Crohn's disease and ulcerative colitis damage the gut wall and trigger this neutrophil response. Irritable bowel syndrome causes similar symptoms - cramping, altered bowel habits - without damaging the gut wall, so calprotectin usually stays low. That contrast is the test's main clinical use: helping a doctor decide who needs a colonoscopy for suspected IBD and who likely has a functional condition that doesn't.
- Gut infections, including bacterial food poisoning - Nonsteroidal anti-inflammatory drugs (NSAIDs) taken regularly - Colorectal cancer, in some cases - Diverticulitis and other causes of intestinal inflammation
A raised result flags inflammation without naming its cause, and a normal result doesn't fully rule out IBD, especially early or mild disease. Your doctor reads it alongside your symptoms and history, and usually orders further tests - blood work, imaging, or a colonoscopy - to reach an actual diagnosis rather than treating the calprotectin number alone.
Many labs treat anything above roughly 50 micrograms per gram as raised, though some use a higher cutoff, such as 120 micrograms per gram, before calling a result strongly suggestive of active inflammation. Ranges vary by lab, so check the reference value printed on your own report.
A normal result makes IBD considerably less likely, but it doesn't rule it out completely, especially if inflammation is mild or limited to a small area. Your doctor weighs it alongside your symptoms before deciding whether further testing is needed.
No, it only shows that inflammation is present somewhere in the gut. A colonoscopy with tissue biopsy is what actually distinguishes Crohn's disease from ulcerative colitis or confirms IBD in the first place.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Yes, regularly taking NSAIDs like ibuprofen can raise calprotectin even without IBD, so tell your doctor about any regular pain medicines before the test. Recent gut infections can also raise the level temporarily.
There's no fixed preparation for most patients, but ask your doctor or the centre about any medicines you're taking, since some can affect the result. Follow whatever specific collection instructions come with your sample container.
A falling calprotectin level over time can show that treatment is calming gut inflammation, sometimes before symptoms fully settle. Doctors use repeat testing this way to track disease activity without needing a colonoscopy each time.