What is a normal calprotectin level?

There is no single normal level that applies everywhere. 50 µg/g was the cut-off used in most of the studies behind NICE's guidance for adults, but ranges differ between laboratories and tests, so the range printed on your own report is the one to use.

Does a calprotectin over 50 mean I have IBD?

No. A result above 50 means your doctor should look further, but it can also be raised by painkillers, acid-reducing tablets, infections and other bowel conditions. In one study, 36% of people with a completely normal colonoscopy had a result above 50.

Can calprotectin tell IBS from IBD?

It helps. NICE recommends it as an option to help doctors tell IBD from IBS in adults with recent bowel symptoms when cancer is not suspected, but it is one part of the assessment, not a diagnosis on its own.

Is µg/g the same as mg/kg for calprotectin?

Yes. 1 mg/kg is the same as 1 µg/g, so a result of 120 mg/kg is 120 µg/g. Differences between laboratories come from the test used, not the unit.

Why did my calprotectin change when I feel the same?

Results vary between samples, by a median of 40% to 52% within a single day in active ulcerative colitis, and different laboratory tests can give results up to five times apart. A repeat on the same test usually tells you more than one surprising number.

What calprotectin level is remission in Crohn's or colitis?

There is no single remission number. The AGA suggests that under 150 µg/g (with a normal CRP in Crohn's) can rule out active inflammation in people whose symptoms are quiet, and your IBD team may use its own thresholds.

Should a high calprotectin be repeated?

Often, yes. One sample is noisy, and two raised results in a row carry much more weight: people with IBD in remission whose results were raised twice in a row had a 53% to 83% chance of a relapse within two to three months in the studies reviewed.

Faecal Calprotectin Result Explainer

Understand your faecal calprotectin number in plain language.

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About 2 minutes
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Updated October 3, 2026

The short answer

Faecal calprotectin measures a protein released by white blood cells into the bowel, so it rises with bowel inflammation. In adults with new bowel symptoms and no diagnosis, the evidence behind NICE's guidance mostly used 50 µg/g as the line for whether inflammation is likely enough to look further. If you already have Crohn's or ulcerative colitis, the result is read against your own previous results from the same laboratory.

How to use the Calprotectin Result Explainer

1Enter the calprotectin number from your report in µg/g (the same as mg/kg).
2Say whether you have a diagnosis of Crohn's disease or ulcerative colitis.
3Optionally add your previous result to see how much it has changed.
4Get a plain explanation of what the number can and cannot tell you, and when to speak to a doctor sooner.

What calprotectin measures

Calprotectin is a protein inside neutrophils, a type of white blood cell. When the bowel lining is inflamed, neutrophils move into it and calprotectin ends up in the stool, so the number is a measure of inflammation at the time of the sample, not of symptoms.

It is a concentration, not a severity score. It can be raised by things other than inflammatory bowel disease, including common painkillers, aspirin, acid-reducing tablets, gut infections and polyps, and it rises with age.

Situation	How the result is usually read	Source
Adult with new bowel symptoms, no diagnosis, cancer not suspected	50 µg/g was the cut-off in most of the evidence NICE used to help tell IBD from IBS; NICE did not fix a single cut-off	NICE DG11
Crohn's or UC with quiet symptoms	Under 150 µg/g (with a normal CRP in Crohn's) suggested to rule out active inflammation	AGA 2023
Crohn's or UC, any time	Compared with your own previous results from the same laboratory	Labaere 2014

Why your lab's range wins

Calprotectin tests are not standardised against a common reference. A comparison of six assays found results up to five times apart on the same samples, so a number is only directly comparable with others from the same test.

Results also move between samples. In active ulcerative colitis, samples from the same day varied by a median of 40% to 52%. That is why a single unexpected result is usually repeated, and why your laboratory's printed range and your doctor's reading take priority over any general cut-off.

What changes the number	What the research found
Which laboratory test is used	Up to 5-fold differences between assays
Which bowel movement you sampled	Median within-day variation of 40% to 52% in active UC
Medicines	Acid-reducing tablets, NSAID painkillers and aspirin linked with raised results
Sample left too long	Stable for 3 days at room temperature, about 28% lower after 7 days

What the result cannot tell you

It cannot diagnose or rule out IBD on its own. A doctor reads it alongside your symptoms, blood tests, examination and, when needed, a colonoscopy or imaging.

For more on reading your number, see what calprotectin levels mean in ulcerative colitis and high calprotectin with no symptoms.

Frequently asked questions

What is a normal calprotectin level?: There is no single normal level that applies everywhere. 50 µg/g was the cut-off used in most of the studies behind NICE's guidance for adults, but ranges differ between laboratories and tests, so the range printed on your own report is the one to use.
Does a calprotectin over 50 mean I have IBD?: No. A result above 50 means your doctor should look further, but it can also be raised by painkillers, acid-reducing tablets, infections and other bowel conditions. In one study, 36% of people with a completely normal colonoscopy had a result above 50.
Can calprotectin tell IBS from IBD?: It helps. NICE recommends it as an option to help doctors tell IBD from IBS in adults with recent bowel symptoms when cancer is not suspected, but it is one part of the assessment, not a diagnosis on its own.
Is µg/g the same as mg/kg for calprotectin?: Yes. 1 mg/kg is the same as 1 µg/g, so a result of 120 mg/kg is 120 µg/g. Differences between laboratories come from the test used, not the unit.
Why did my calprotectin change when I feel the same?: Results vary between samples, by a median of 40% to 52% within a single day in active ulcerative colitis, and different laboratory tests can give results up to five times apart. A repeat on the same test usually tells you more than one surprising number.
What calprotectin level is remission in Crohn's or colitis?: There is no single remission number. The AGA suggests that under 150 µg/g (with a normal CRP in Crohn's) can rule out active inflammation in people whose symptoms are quiet, and your IBD team may use its own thresholds.
Should a high calprotectin be repeated?: Often, yes. One sample is noisy, and two raised results in a row carry much more weight: people with IBD in remission whose results were raised twice in a row had a 53% to 83% chance of a relapse within two to three months in the studies reviewed.

What Calprotectin Levels Mean in Ulcerative Colitis
A calprotectin number is a concentration, not a severity score. What the value means in UC, why the same stool gives different numbers, and which thresholds matter.
High Calprotectin but No Symptoms: What It Means
A high faecal calprotectin while you feel fine usually means real inflammation you cannot feel, but not always. What the number means and what happens next.
What Can Be Mistaken for Ulcerative Colitis?
Infection, STI proctitis, Crohn's colitis, medicines and age-related colitis can all pass for UC. How often the label changes, and the tests that tell them apart.
How to Tell If You're in a Crohn's Flare
Symptoms alone cannot confirm a Crohn's flare. How to read your own baseline, rule out the look-alikes, and use the tests that actually settle it.
How to Know If Your Ulcerative Colitis Is Flaring
A flare means active inflammation, not just a bad week. How to compare today with your own baseline, score yourself, and know when a test is needed.

Sources

National Institute for Health and Care Excellence. Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel. Diagnostics guidance DG11 (now HealthTech guidance HTG320). London: NICE; 2013. Available from: https://www.nice.org.uk/guidance/htg320
Singh S, Ananthakrishnan AN, Nguyen NH, Cohen BL, Velayos FS, Weiss JM, et al. AGA clinical practice guideline on the role of biomarkers for the management of ulcerative colitis. Gastroenterology. 2023;164(3):344-72. doi:10.1053/j.gastro.2022.12.007
Ananthakrishnan AN, Adler J, Chachu KA, Nguyen NH, Siddique SM, Weiss JM, et al. AGA clinical practice guideline on the role of biomarkers for the management of Crohn's disease. Gastroenterology. 2023;165(6):1367-99. doi:10.1053/j.gastro.2023.09.029
Labaere D, Smismans A, Van Olmen A, Christiaens P, D'Haens G, Moons V, et al. Comparison of six different calprotectin assays for the assessment of inflammatory bowel disease. United European Gastroenterol J. 2014;2(1):30-7. doi:10.1177/2050640613518201
Lasson A, Stotzer PO, Ohman L, Isaksson S, Sapnara M, Strid H. The intra-individual variability of faecal calprotectin: a prospective study in patients with active ulcerative colitis. J Crohns Colitis. 2015;9(1):26-32. doi:10.1016/j.crohns.2014.06.002
Calafat M, Cabre E, Manosa M, Lobaton T, Marin L, Domenech E. High within-day variability of fecal calprotectin levels in patients with active ulcerative colitis: what is the best timing for stool sampling? Inflamm Bowel Dis. 2015;21(5):1072-6. doi:10.1097/MIB.0000000000000349
Lundgren D, Eklof V, Palmqvist R, Hultdin J, Karling P. Proton pump inhibitor use is associated with elevated faecal calprotectin levels. A cross-sectional study on subjects referred for colonoscopy. Scand J Gastroenterol. 2019;54(2):152-7. doi:10.1080/00365521.2019.1566493
Heida A, Park KT, van Rheenen PF. Clinical utility of fecal calprotectin monitoring in asymptomatic patients with inflammatory bowel disease: a systematic review and practical guide. Inflamm Bowel Dis. 2017;23(6):894-902. doi:10.1097/MIB.0000000000001082

Cite this tool

Clairop. Calprotectin Result Explainer. www.clairop.com/tools/calprotectin-result-explainer. Updated October 3, 2026.

Clairop is a general wellness app for people living with a diagnosed digestive condition. It does not replace professional medical care, diagnosis, or treatment. Always follow your healthcare provider's advice.

Clairop logs meals, symptoms and stool in seconds, then looks for the foods your gut reacts to, including reactions that land days later.

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