Fecal calprotectin
Protein from white blood cells in stool, a marker for inflammation in the intestines
Also known as
Definition
Calprotectin is a protein released by neutrophils when they move into inflamed intestinal tissue. It mixes with the stool and can be measured there; a small amount is normal. The test shows whether inflammation in the intestines is likely but does not identify its cause. Above all, it helps distinguish inflammatory bowel disease (IBD) from irritable bowel syndrome (IBS).
| Parameter | Value |
|---|---|
| Unit | µg/g stool |
| Reference Range | Commonly used cut-off for adults: below 50 µg/g is considered unremarkable. Labs and assays sometimes use other cut-offs, such as 60 or 100 µg/g; the range on your own report is what counts. Discuss your result with your doctor. |
Agree on your personal target range with your doctor.
1 µg/g equals 1 mg/kg.
↓ What a low value means
A low or normal value usually speaks against inflammation in the intestines. With ongoing symptoms, non-inflammatory causes such as IBS become more likely; your doctor decides which further tests make sense. A normal value does not completely rule out inflammation. Such false negative results mainly occur in children.
↑ What a high value means
A raised value points to inflammation in the intestines; the higher it is, the more pronounced the inflammation usually is. Very high values may be related to inflammatory bowel disease such as Crohn's disease or ulcerative colitis, or to bacterial intestinal infections. Moderately raised values can occur with celiac disease, certain intestinal infections such as Clostridioides difficile, while taking nonsteroidal anti-inflammatory drugs (NSAIDs), with treated IBD or with intestinal tumors, among others. The test is often repeated after a few weeks. Your doctor interprets the result and decides on possible further tests such as a colonoscopy.
When to test
The test is considered when diarrhea, abdominal pain or cramps last longer than a few days or keep coming back, with blood or mucus in the stool, unintended weight loss, and to monitor known IBD. You collect the sample according to the instructions, without urine, toilet paper or toilet water. NSAIDs and proton pump inhibitors can affect the result; only stop medicines after talking to your doctor.
Frequently asked questions
Is calprotectin a blood test or a stool test? +
A stool test. You hand in a small stool sample in a container or kit from your practice or lab. Blood values such as CRP or ESR show inflammation in general; calprotectin in stool captures inflammation in the intestines more accurately.
Can the test tell IBD and IBS apart? +
It helps, because only IBD involves inflammation of the intestinal lining. The test alone does not make a diagnosis. Raised values are usually followed by further tests, while normal values often make a colonoscopy unnecessary.
Which medicines can affect the result? +
Mainly nonsteroidal anti-inflammatory drugs such as ibuprofen, aspirin or naproxen, and proton pump inhibitors such as omeprazole. Whether you should pause anything before the test is for your doctor to decide.
Why is a raised value often repeated? +
Because several causes, some of them temporary, can raise the value, a raised result is often measured again after a few weeks to see whether it changes.
Fecal calprotectin
Sources
- MedlinePlus, National Library of Medicine: Calprotectin Stool Test
- NICE, National Institute for Health and Care Excellence: Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel (HTG320), chapter 4
- NICE, National Institute for Health and Care Excellence: Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel (HTG320), chapter 6
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.