A calprotectin test (also called a fecal or stool calprotectin test) measures a protein that white blood cells release into your gut when the intestinal lining is inflamed. At one major US lab, a result under 50 µg/g is normal, 50 to 120 µg/g is borderline, and above 120 µg/g is abnormal[1]. A high number signals inflammation, not a specific disease.
Doctors mostly use the test to tell inflammatory bowel disease (IBD) apart from irritable bowel syndrome (IBS), and to track IBD once it is diagnosed. Below: what the test measures, how to collect the sample, what each result range means, what can raise the number falsely, and what usually happens next.
What is calprotectin, and what does the test measure?
It measures calprotectin, a calcium- and zinc-binding protein that makes up about 60% of the protein inside neutrophils, the white blood cells that rush to inflamed tissue[2]. When neutrophils move into an inflamed gut wall, calprotectin spills into the bowel and leaves the body in stool[2].
The result is reported in micrograms per gram of stool (µg/g). It reflects inflammation anywhere along the gut, so a high result tells your clinician that something is inflamed, not what or where[1]. This is very different from microbiome testing, which profiles the microbes in stool rather than your immune response. Some functional stool panels, such as the GI-MAP test, include a calprotectin line alongside their microbe results.
Why is a calprotectin test ordered?
The main reason is to sort out persistent diarrhea and belly pain: is it inflammatory disease that needs a colonoscopy, or IBS that does not? IBS and IBD can cause near-identical symptoms, but in studies calprotectin could not separate people with IBS from healthy controls, while IBD raises it[3].
Does IBS show up in calprotectin?
Usually not. IBS does not typically raise calprotectin, which is why major guidelines now build the test into the IBS work-up:
- American College of Gastroenterology (2021): suggests checking fecal calprotectin in people with suspected IBS and diarrhea to rule out IBD[4].
- British Society of Gastroenterology (2021): recommends calprotectin for people under 45 with diarrhea at their first IBS consultation, alongside a blood count, an inflammation blood test and celiac serology[5].
- NICE (UK): supports the test for adults with recent-onset lower gut symptoms being considered for specialist referral, but only when cancer is not suspected[6].
The numbers explain why. In a meta-analysis of adults with IBS-type symptoms, a calprotectin of 40 µg/g or lower meant a 1% or lower chance of having IBD[3]. That is what gives a normal result its value: it lets many people with IBS skip an invasive test[7].
Monitoring Crohn's disease and ulcerative colitis
If you already have Crohn's disease or ulcerative colitis, repeat tests help track inflammation between scopes. The American Gastroenterological Association suggests that, in people with ulcerative colitis whose symptoms are in remission, a calprotectin under 150 µg/g can rule out active inflammation and avoid a routine colonoscopy[8]. Across 24 studies, a level around 152 µg/g was the best cut-off for flagging a coming relapse, though it caught only about 72% of relapses[9].
How do you prepare and collect the sample?
You collect a small stool sample at home with a kit from your clinician or lab. Your medicines, the timing of the sample and how it is stored can all affect the result.
- Tell your clinician about medicines. Anti-inflammatory painkillers (NSAIDs), aspirin and proton pump inhibitors can all push results into the borderline range[1]. Do not stop a prescribed medicine without advice.
- Use the first bowel movement of the morning if you can. In people with active ulcerative colitis, calprotectin rose with longer gaps between bowel movements, and the authors recommended first-morning stool[10]. Another study found morning samples on different days were as reliable as two samples from the same day[11].
- Keep the stool clean. Catch it in the collection device before it touches toilet water or urine, as the kit directs.
- Collect the amount asked for. Mayo Clinic Laboratories asks for 5 g of stool, and it rejects samples taken from diapers[1].
- Return it quickly and store it as directed. That lab accepts refrigerated samples for 72 hours and frozen samples for 7 days[1]. In one study, calprotectin was stable for 3 days at room temperature but fell by an average of 28% after 7 days[10].
Calprotectin normal range: how to read your result
Use the reference range printed on your own report, because cut-offs differ between assays and labs[2]. Most labs use 50 µg/g as the upper limit of normal[2]. The table shows how Mayo Clinic Laboratories and the AGA guideline frame the numbers.
| Result (µg/g) | Lab category | What it usually suggests |
|---|---|---|
| Under 50 | Normal | Active gut inflammation is unlikely; IBD is improbable in people with IBS-type symptoms[3] |
| 50 to 120 | Borderline | Mild inflammation, treated IBD, or a medicine effect from NSAIDs, aspirin or PPIs[1] |
| Over 120 | Abnormal[1] | Active inflammation; the cause needs working out |
| Under 150 in known UC, in remission | Guideline threshold | Can help rule out active inflammation without a routine scope[8] |
| Over 150 in known UC, with symptoms | Guideline threshold | Can inform treatment decisions[8] |
A higher number generally means more inflammation. In a 30-study meta-analysis, people with IBD averaged about 219 µg/g more than people without it[12].
Calprotectin normal range in different age groups
Healthy infants and toddlers run much higher than adults, so adult cut-offs do not apply to them[2]. A 2025 meta-analysis of 23 studies in healthy children estimated these average levels[13]:
| Age | Average calprotectin (µg/g) |
|---|---|
| Under 1 month | 258 |
| 1 to 6 months | 239 |
| 7 to 12 months | 116 |
| 13 to 24 months | 105 |
| 25 to 36 months | 75 |
| 37 to 48 months | 34 |
Between ages 4 and 16, healthy children had a median of 18.8 µg/g, with 95% below 104.5 µg/g, and the upper limit varied with age[14]. Ask the pediatric team which range they use for your child's age.
What does a high calprotectin level mean?
A high calprotectin level means immune cells are active in your gut lining. Several diseases can cause it: IBD is the best-known, but infections, other gut diseases and some medicines raise it too, so a clinician has to match the number to your symptoms and history[1][2].
| Cause | How it relates to calprotectin |
|---|---|
| Inflammatory bowel disease | Levels track how inflamed the gut is; used for diagnosis and monitoring[2] |
| Bacterial gut infection | Can be very high; median 765 µg/g with Salmonella in children, rising with severity[15] |
| NSAIDs, aspirin, PPIs | Usually mild to borderline rises[1][16] |
| Celiac disease, diverticulitis, peptic ulcer | Linked to raised levels; evidence is less developed[2] |
| Polyps and gut cancers | Can raise levels, but the test is poor at detecting cancer[2][12] |
| Older age | Each extra year slightly raised the odds of a result above 50 µg/g[16] |
The infections on this list are where the gut microbiome comes in. In children with infectious diarrhea, levels were higher with bacteria such as Salmonella enterica and Campylobacter jejuni than with viruses, and they rose as illness became more severe[15]. See celiac disease and diverticulitis for more on those conditions.
Medicines that can raise calprotectin
Common medicines are a well-documented cause of borderline results in people without gut disease:
- NSAIDs: in two small randomized crossover trials, 7 to 14 days of indomethacin or naproxen significantly raised calprotectin in healthy volunteers[17].
- PPIs, NSAIDs and aspirin: among 590 adults whose colonoscopy was normal, 36% still had a calprotectin above 50 µg/g. PPI users had 3.8 times the odds, NSAID users 2.4 times and aspirin users 2.9 times[16].
- In IBS: people with a recent PPI prescription had levels of 66 µg/g vs. 23 µg/g without one, and a result over 50 µg/g doubled the rate of colonoscopy referral (40% vs. 19%)[18].
Is calprotectin a tumor marker?
No. In a meta-analysis, calprotectin detected colorectal cancer with a sensitivity of only 36% and a specificity of 71%, and the authors concluded it cannot be recommended for cancer screening[12]. It also cannot reliably tell cancer from benign polyps[2]. A normal calprotectin does not rule out cancer, which is why NICE limits the test to people in whom cancer is not suspected[6].
How accurate is the calprotectin test?
The test is best at ruling IBD out. It is weaker at ruling it in, because so many other things raise the number.
| Study | What it found |
|---|---|
| 17 studies, 1,956 adults (IBD vs. IBS) | Sensitivity 85.8%, specificity 91.7%; where IBD is rare (1%), a negative result was correct 99.8% of the time, but only 9% of positive results were IBD[19] |
| 19 studies, 5,032 adults vs. colonoscopy | Sensitivity 88%, specificity 80%; using the test could cut colonoscopies by about two-thirds[7] |
| 19 studies, 2,499 people with IBD | Calprotectin caught 88% of active disease on endoscopy vs. 49% for C-reactive protein, a blood test[20] |
Two limits matter in practice. First, a positive result in someone with a low chance of IBD is often a false alarm[19]. Second, calprotectin was more sensitive in ulcerative colitis than in Crohn's disease, so a normal result in suspected Crohn's needs to fit the rest of the picture[20]. Single results also vary: one study found large swings between bowel movements on the same day[10].
What calprotectin level warrants a colonoscopy?
There is no single cut-off, and a high calprotectin does not automatically mean a colonoscopy. Because the test cannot name the cause, labs interpret it alongside endoscopy, tissue biopsies and imaging[1]. A borderline result can reflect a medicine or mild inflammation, so it is read against your history before anything invasive[1].
What tends to shape the decision:
- How high the number is. Results above about 120 µg/g are reported as abnormal, while 50 to 120 µg/g is a grey zone[1].
- Your age and cancer risk. Guidelines restrict this test to people in whom cancer is not suspected, so symptoms or risk factors that raise that concern change the plan[6][5].
- Known IBD. For ulcerative colitis, the AGA suggests a scope when symptoms and calprotectin disagree, such as feeling well with a raised level[8].
If a colonoscopy comes back normal despite a raised calprotectin, the outlook is generally reassuring. In 585 people with a normal colonoscopy, those with calprotectin above 50 µg/g were no more likely than those below it to be diagnosed with a significant gut disease over three years[21].
If you are waiting for a result or a follow-up, keep a simple symptom record (stool frequency, blood, pain, weight) and a list of medicines you took in the weeks before the test. Our Bristol stool chart guide and chronic diarrhea page can help you describe your symptoms clearly.
This article is for general educational purposes and is not medical advice. A calprotectin result needs to be interpreted by the clinician who ordered it, alongside your symptoms and other tests. Talk to a qualified healthcare professional before changing any medicine or acting on a result, particularly if you are pregnant, immunocompromised, taking prescription medication, or managing a diagnosed condition.
Frequently Asked Questions
Is high calprotectin an emergency, and when should you worry?
A high number on its own is not usually treated as an emergency, because many causes, including short infections and common medicines, raise it. It does need prompt follow-up with the clinician who ordered it. If you have heavy bleeding, severe pain or feel very unwell, seek care promptly rather than waiting on a test result.
Can stress cause high calprotectin levels?
We did not find a study showing that psychological stress raises fecal calprotectin. Irritable bowel syndrome is the condition the test is used to separate from inflammatory bowel disease, because IBS does not usually raise calprotectin. A clearly high result points to inflammation and is worth investigating rather than putting down to stress.
What bacteria cause high calprotectin?
Bacterial gut infections can push calprotectin very high. In a study of children with infectious diarrhea, Salmonella infections produced a median level of 765 µg/g, and levels rose with how severe the illness was. Campylobacter infection also raised levels in that study, and bacterial infections generally produced higher results than viral ones.
What should I eat if my calprotectin is high?
No food or diet in the research we reviewed lowers calprotectin directly. The number reflects inflammation, so what helps depends on the cause, such as treating an infection, managing inflammatory bowel disease or reviewing anti-inflammatory painkillers with your clinician. If you have diagnosed Crohn's disease or ulcerative colitis, ask your care team before changing your diet.
Can celiac disease raise calprotectin?
Yes. Celiac disease is one of the conditions linked to raised fecal calprotectin, although the evidence is thinner than for inflammatory bowel disease. That is why guidelines pair calprotectin with celiac blood tests when someone first presents with IBS-type symptoms. A normal calprotectin does not rule out celiac disease, so the two tests answer different questions.
Can acid reflux or hemorrhoids cause high calprotectin?
We did not find good studies on hemorrhoids or reflux itself. The better-documented link is the medicine: people taking proton pump inhibitors for reflux had nearly four times the odds of a calprotectin above 50 µg/g in one study of adults with a normal colonoscopy. Tell your clinician about acid-reducing medicines before the test, but do not stop a prescribed drug without advice.
How long do calprotectin test results take?
It depends on the laboratory and on how quickly the sample reaches it. Labs set strict storage windows: Mayo Clinic Laboratories, for example, rejects refrigerated samples that arrive more than 72 hours after collection. Return the sample promptly, follow the kit's storage instructions, and ask the ordering office when results usually come back.
References
- Mayo Clinic Laboratories. CALPR - Calprotectin, Feces: Test Overview. Mayo Clinic Laboratories Test Catalog. 2026. Available at: https://www.mayocliniclabs.com/test-catalog/overview/63016 ↩
- Pathirana WGW, Chubb SP, Gillett MJ, Vasikaran SD. Faecal Calprotectin. The Clinical Biochemist Reviews. 2018;39(3):77-90. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC6370282/ ↩
- Menees SB, Powell C, Kurlander J, Goel A, Chey WD. A Meta-Analysis of the Utility of C-Reactive Protein, Erythrocyte Sedimentation Rate, Fecal Calprotectin, and Fecal Lactoferrin to Exclude Inflammatory Bowel Disease in Adults With IBS. American Journal of Gastroenterology. 2015;110(3):444-454. doi:10.1038/ajg.2015.6 ↩
- Lacy BE, Pimentel M, Brenner DM, et al.. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. American Journal of Gastroenterology. 2020;116(1):17-44. doi:10.14309/ajg.0000000000001036 ↩
- Vasant DH, Paine PA, Black CJ, et al.. British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. Gut. 2021;70(7):1214-1240. doi:10.1136/gutjnl-2021-324598 ↩
- National Institute for Health and Care Excellence. Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel (HTG320, formerly DG11): Recommendations. NICE. 2013. Available at: https://www.nice.org.uk/guidance/htg320/chapter/1-Recommendations ↩
- Petryszyn P, Staniak A, Wolosianska A, Ekk-Cierniakowski P. Faecal calprotectin as a diagnostic marker of inflammatory bowel disease in patients with gastrointestinal symptoms: meta-analysis. European Journal of Gastroenterology & Hepatology. 2019;31(11):1306-1312. doi:10.1097/meg.0000000000001509 ↩
- Singh S, Ananthakrishnan AN, Nguyen NH, et al.. AGA Clinical Practice Guideline on the Role of Biomarkers for the Management of Ulcerative Colitis. Gastroenterology. 2023;164(3):344-372. doi:10.1053/j.gastro.2022.12.007 ↩
- Shi JT, Chen N, Xu J, et al.. Diagnostic Accuracy of Fecal Calprotectin for Predicting Relapse in Inflammatory Bowel Disease: A Meta-Analysis. Journal of Clinical Medicine. 2023;12(3):1206. doi:10.3390/jcm12031206 ↩
- Lasson A, Stotzer PO, Öhman L, Isaksson S, Sapnara M, Strid H. The intra-individual variability of faecal calprotectin: A prospective study in patients with active ulcerative colitis. Journal of Crohn's and Colitis. 2014;9(1):26-32. doi:10.1016/j.crohns.2014.06.002 ↩
- Kristensen V, Malmstrøm GH, Skar V, Røseth A, Moum B. Clinical importance of faecal calprotectin variability in inflammatory bowel disease: intra-individual variability and standardisation of sampling procedure. Scandinavian Journal of Gastroenterology. 2015;51(5):548-555. doi:10.3109/00365521.2015.1117650 ↩
- von Roon AC, Karamountzos L, Purkayastha S, et al.. Diagnostic Precision of Fecal Calprotectin for Inflammatory Bowel Disease and Colorectal Malignancy. The American Journal of Gastroenterology. 2007;102(4):803-813. doi:10.1111/j.1572-0241.2007.01126.x ↩
- Zeng J, Yu W, Gao X, Yu Y, Zhou Y, Pan X. Establishing reference values for age-related fecal calprotectin in healthy children aged 0–4 years: a systematic review and meta-analysis. PeerJ. 2025;13:e19572. doi:10.7717/peerj.19572 ↩
- Roca M, Rodriguez Varela A, Carvajal E, et al.. Fecal calprotectin in healthy children aged 4–16 years. Scientific Reports. 2020;10(1):20565. doi:10.1038/s41598-020-77625-7 ↩
- Chen C, Huang J, Chang C, Kong M. Fecal Calprotectin as a Correlative Marker in Clinical Severity of Infectious Diarrhea and Usefulness in Evaluating Bacterial or Viral Pathogens in Children. Journal of Pediatric Gastroenterology and Nutrition. 2012;55(5):541-547. doi:10.1097/mpg.0b013e318262a718 ↩
- Lundgren D, Eklöf 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. Scandinavian Journal of Gastroenterology. 2019;54(2):152-157. doi:10.1080/00365521.2019.1566493 ↩
- Meling TR, Aabakken L, Røseth A, Osnes M. Faecal Calprotectin Shedding after Short-Term Treatment with Non-Steroidal Anti-Inflammatory Drugs. Scandinavian Journal of Gastroenterology. 1996;31(4):339-344. doi:10.3109/00365529609006407 ↩
- Sandberg-Janzon A, Karling P. Prescription of NSAIDs and proton pump inhibitors are associated with increased faecal calprotectin levels in patients with functional bowel disorder: an observational study. Scandinavian Journal of Gastroenterology. 2025;60(7):635-642. doi:10.1080/00365521.2025.2512368 ↩
- Dajti E, Frazzoni L, Iascone V, et al.. Systematic review with meta-analysis: Diagnostic performance of faecal calprotectin in distinguishing inflammatory bowel disease from irritable bowel syndrome in adults. Alimentary Pharmacology & Therapeutics. 2023;58(11-12):1120-1131. doi:10.1111/apt.17754 ↩
- Mosli MH, Zou G, Garg SK, et al.. C-Reactive Protein, Fecal Calprotectin, and Stool Lactoferrin for Detection of Endoscopic Activity in Symptomatic Inflammatory Bowel Disease Patients: A Systematic Review and Meta-Analysis. American Journal of Gastroenterology. 2015;110(6):802-819. doi:10.1038/ajg.2015.120 ↩
- Hovstadius H, Lundgren D, Karling P. Elevated Faecal Calprotectin in Patients with a Normal Colonoscopy: Does It Matter in Clinical Practice? A Retrospective Observational Study. Inflammatory Intestinal Diseases. 2021;6(2):101-108. doi:10.1159/000513473 ↩