Lab result explainedInflammationLast updated November 11, 2026

Fecal calprotectin test: normal range, what a high level means, and how it separates IBS from IBD

Fecal calprotectin (FCP) · Fecal calprotectin (stool sample); often ordered with CBC, CRP, ferritin, celiac serology and stool infection tests · reported in µg/g of stool (identical to mg/kg)

Fecal calprotectin is a protein released by neutrophils, the white blood cells that flood into the bowel wall when it is inflamed, and measuring it in a stool sample tells you how much inflammation is present in your intestine right now. In healthy adults the level is under 50 micrograms per gram of stool (µg/g). Values between 50 and 150 to 200 µg/g are borderline and usually repeated, and values above 150 to 250 µg/g indicate active inflammation that is most often inflammatory bowel disease (IBD), meaning Crohn's disease or ulcerative colitis, or an intestinal infection.

The test's main job is to answer one question without a colonoscopy: are these bowel symptoms coming from inflammation, or from irritable bowel syndrome (IBS), which does not inflame the bowel? In adults with chronic diarrhea, pain or bloating, a calprotectin under 50 µg/g makes IBD very unlikely (a meta-analysis of 13 studies found a sensitivity of 93 percent and specificity of 96 percent), and the UK NICE guidance endorses it precisely for that purpose. It is also used to monitor people who already have IBD, where a level under about 150 to 250 µg/g corresponds to a healed bowel lining and a rising level warns of a flare weeks before symptoms.

Calprotectin is sensitive but not specific. It rises with anything that brings neutrophils into the gut: stomach bugs, NSAIDs such as ibuprofen, acid-suppressing drugs, diverticulitis, bowel polyps and cancer, and even a few days of gastrointestinal bleeding. It is also naturally higher in babies and toddlers and slightly higher after age 60. A single raised value is a prompt to look further, not a diagnosis, and the most common outcome of a value between 50 and 200 is a normal repeat test four to six weeks later.

FCP at a glance

  • What it is: a neutrophil protein measured in stool; the amount reflects how many white cells are moving into the bowel wall, and so how inflamed the bowel is.
  • Normal: under 50 µg/g in adults (some labs 'under 50' or 'under 100'; toddlers and infants run higher). Labs and assays differ.
  • Borderline: 50–150 µg/g (some labs to 200 or 250); repeat in 4 to 6 weeks off NSAIDs; roughly 1 in 3 turn out to have organic disease.
  • High: above 150–250 µg/g suggests active inflammation, usually IBD or infection; above 500 to 1,000 µg/g typically means extensive active colitis.
  • A normal result in an adult with typical IBS symptoms and no red flags makes IBD very unlikely and often avoids colonoscopy; in IBD, a value under about 150–250 µg/g indicates mucosal healing.
  • Next step for a high value: stool infection tests, CBC, CRP and ferritin, review of NSAID and PPI use, and colonoscopy if it stays raised or you have blood in the stool, weight loss or anemia.

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What FCP measures

Calprotectin makes up about 60 percent of the protein inside the cytoplasm of neutrophils. When the lining of the intestine is inflamed, neutrophils migrate across it into the bowel lumen, break down and release calprotectin, which binds calcium and zinc, resists digestion and is stable in stool at room temperature for several days. The concentration in a stool sample is therefore a direct, quantitative readout of neutrophil traffic into the gut over the previous day or so. It correlates well with what a colonoscopy shows and with radiolabeled white-cell scans, the older reference method.

Most labs use an ELISA or a chemiluminescent immunoassay reporting in micrograms of calprotectin per gram of stool (µg/g, the same as mg/kg); point-of-care and smartphone-based home tests also exist and are used in IBD monitoring programs. Only a small sample (about the size of a pea) is needed from one bowel movement. The result does not depend on diet or fasting, but it can vary by up to two-fold between consecutive stools, is higher in the first stool of the morning, and is affected by stool consistency, so repeat tests are compared with that variability in mind.

Children under 4 normally have higher levels: infants under 1 year commonly measure 100 to 500 µg/g, and children aged 1 to 4 often exceed the adult cut-off, so pediatric labs use age-specific limits. Adults over about 60 run slightly higher. Calprotectin reflects neutrophilic inflammation only; conditions with mainly lymphocytic inflammation, such as microscopic colitis and celiac disease, often produce normal or only mildly raised results, and it does not detect functional disorders at all.

Normal range for FCP

Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.

GroupTypical range (µg/g of stool (identical to mg/kg))Notes
Adults, normalBelow 50 µg/gInflammatory bowel disease is very unlikely in a symptomatic adult with no red flags. Some labs use below 100 µg/g.
Adults, borderline / indeterminate50–150 µg/g (some labs 50–200 or 50–250)Repeat in 4 to 6 weeks after stopping NSAIDs; about two thirds normalize. Persistently raised values proceed to colonoscopy.
Adults, raised150–250 µg/g and aboveActive neutrophilic inflammation likely: IBD, infection, NSAID damage, diverticulitis, polyps or cancer. Sensitivity 93 percent and specificity 96 percent for IBD at the 50 µg/g cut-off in adults.
Adults, markedly raisedAbove 500–1,000 µg/gExtensive active colitis or ileitis, severe infectious colitis (including C. difficile); values of several thousand occur in severe ulcerative colitis.
Known IBD, mucosal healing (STRIDE-II target)Below 150 µg/g (many centers accept below 250)Corresponds to endoscopic remission. Above 250 µg/g predicts active mucosal disease; a rise above 150–300 predicts a flare within weeks to months.
Known Crohn's disease after surgeryBelow 100 µg/g reassuring; above 100–150 suggests recurrenceUsed to decide on and time post-operative colonoscopy.
Infants under 1 yearOften 100–500 µg/gNot interpretable against adult cut-offs; breastfed infants run higher.
Children 1–4 yearsUp to about 100–200 µg/gPediatric labs use age-specific reference limits. From about age 4 the adult cut-off of 50 µg/g applies.

High fecal calprotectin

A raised calprotectin means neutrophils are entering your bowel: there is inflammation, and the height of the number gives a rough idea of how much. Values between 50 and 150 µg/g are low-grade and non-specific. In this band, recent NSAID use (including low-dose aspirin), a proton pump inhibitor, a recent stomach bug, a hemorrhoidal bleed, diverticular disease or simply being over 60 are at least as likely as IBD, and most guidelines advise a repeat test in 4 to 6 weeks off NSAIDs before anything else. Roughly one adult in three with a borderline value turns out to have an organic cause; the rest normalize.

Values above 150 to 250 µg/g in an adult are much more likely to reflect disease. In someone with chronic diarrhea, abdominal pain, urgency, blood or mucus in the stool, weight loss or anemia, a level at this height usually leads straight to stool infection testing and colonoscopy, and in this setting the positive predictive value for IBD is high. Values above 500 to 1,000 µg/g almost always mean extensive active inflammation (active ulcerative colitis or Crohn's colitis, a severe infectious colitis such as C. difficile, Salmonella, Shigella or Campylobacter, or ischemic colitis) and warrant prompt assessment. Calprotectin cannot say which of these it is; that needs stool cultures, PCR panels and endoscopy.

In someone who already has IBD, the meaning is different and more precise: calprotectin is a surrogate for what the bowel lining looks like. Levels under about 150 to 250 µg/g indicate the lining has healed, which is now the treatment target (STRIDE-II), and levels above 250 µg/g indicate active mucosal inflammation even if you feel well. A level that climbs on two consecutive tests predicts a clinical flare in the following weeks to months with roughly 80 percent accuracy, which is why many clinics test every 3 to 6 months and act on a rise before symptoms return. After bowel surgery for Crohn's disease, a level above about 100 to 150 µg/g is used to time a check colonoscopy for recurrence.

Common causes

  1. Crohn's disease

    Active Crohn's disease of the colon or terminal ileum raises calprotectin, often to several hundred µg/g or more. Disease confined to the small bowel beyond the reach of colonoscopy or to the upper gut can give lower values, so a normal result does not fully exclude small-bowel Crohn's.

  2. Ulcerative colitis

    Produces the highest values because the inflamed surface is large and continuous; active extensive colitis commonly exceeds 1,000 µg/g. Levels fall into the hundreds with partial response and under 150 to 250 µg/g with mucosal healing.

  3. Infectious gastroenteritis

    Bacterial infections (Salmonella, Shigella, Campylobacter, Clostridioides difficile, enteroinvasive E. coli) drive neutrophils into the gut and give values from a few hundred to several thousand µg/g that fall back to normal within 4 to 6 weeks of recovery. Viral gastroenteritis causes smaller rises. Giardia and other parasites cause modest elevations.

  4. NSAIDs and aspirin

    Ibuprofen, naproxen, diclofenac and even low-dose aspirin damage the small bowel and colon lining. Two weeks of a standard NSAID dose raised calprotectin above the normal limit in about 40 to 70 percent of healthy volunteers in early studies, typically to 50 to 200 µg/g. Stop NSAIDs for at least 2 weeks (ideally 4) before a repeat test.

  5. Proton pump inhibitors

    Omeprazole, pantoprazole and similar drugs are associated with modestly raised calprotectin (often in the 50 to 150 µg/g range), probably through changes in gut bacteria and small-bowel overgrowth. The effect is enough to turn a normal result borderline.

  6. Colorectal cancer and large polyps

    Tumors and large adenomas attract neutrophils and bleed, giving mild to moderate rises. Calprotectin is far less specific than the FIT test for this purpose, but a persistently raised level in someone over 50 is one more reason for colonoscopy.

  7. Diverticulitis and diverticular disease

    Acute diverticulitis raises calprotectin, often to several hundred µg/g; symptomatic uncomplicated diverticular disease causes smaller persistent rises, particularly in people over 60.

  8. Microscopic colitis, celiac disease and other mainly lymphocytic conditions

    These inflame the lining with lymphocytes rather than neutrophils, so calprotectin is often normal or only mildly raised (50 to 150 µg/g). A normal calprotectin does not exclude them; celiac serology and biopsies are needed.

  9. Gastrointestinal bleeding

    Blood itself contains neutrophils, so a significant bleed from an ulcer, hemorrhoids or a vascular lesion raises calprotectin for a few days; menstrual blood contaminating a sample can do the same.

  10. Age under 4 or over 60, obesity, and recent bowel preparation or endoscopy

    Infants and toddlers run naturally higher levels; older adults slightly higher. Colonoscopy preparation and biopsies transiently raise calprotectin, so sample before, not after, the procedure.

Symptoms that can go with it

  • Diarrhea lasting more than 4 weeks, especially with urgency or waking you at night
  • Blood or mucus in the stool
  • Abdominal pain or cramping, often right lower abdomen in Crohn's disease, left side or whole abdomen in colitis
  • Unintentional weight loss or, in children, poor growth
  • Fatigue and breathlessness from iron-deficiency anemia
  • Fever, mouth ulcers, joint pains, red painful eyes or skin lesions that accompany IBD flares
  • Sometimes none: in monitored IBD a rising calprotectin frequently precedes symptoms by weeks

Read it alongside

  • CRP — raised in about half of people with active IBD; a normal CRP with a high calprotectin is common, since calprotectin is the more sensitive marker for gut inflammation.
  • Complete blood count — anemia, a high platelet count or a high white count support active inflammation; microcytic indices point to iron deficiency from bowel loss.
  • Ferritin and iron saturation — iron deficiency with a raised calprotectin strongly suggests organic bowel disease rather than IBS.
  • Albumin — falls with severe or prolonged bowel inflammation and protein loss.
  • Stool culture, PCR panel and C. difficile toxin — rule out infection, the most common non-IBD cause of a markedly raised calprotectin.
  • tTG-IgA (celiac serology) — ordered in parallel in chronic diarrhea, because celiac disease usually leaves calprotectin normal.
  • FIT test (fecal immunochemical test) — detects hidden blood and is the better test for colorectal cancer screening; the two are complementary.
  • Fecal lactoferrin — an alternative neutrophil marker with similar meaning, used in some US labs; the two are not interchangeable numerically.

What usually happens next

  1. If the result is under 50 µg/g, you have no red flags (bleeding, weight loss, anemia, nocturnal symptoms, family history of IBD or colorectal cancer, age over 50) and your symptoms fit IBS, a colonoscopy is usually not needed; management turns to IBS.
  2. If the result is 50 to 150 µg/g (or up to your lab's indeterminate limit), expect a repeat in 4 to 6 weeks after stopping NSAIDs and, if possible, any PPI, and once any recent stomach bug has settled; a persistently raised repeat leads to colonoscopy.
  3. If the result is above 150 to 250 µg/g, or any value with red-flag symptoms, expect stool infection tests, CBC, CRP, ferritin and referral for colonoscopy with biopsies; MRI or capsule endoscopy follows if the colon is normal and small-bowel Crohn's disease is suspected.
  4. If you have known IBD, ask what your target level is (usually under 150 to 250 µg/g) and how often you will be tested; a rise on two consecutive samples usually prompts an earlier review or a treatment adjustment rather than waiting for symptoms.
  5. Collect the sample from the first stool of the day, before any bowel preparation, not during menstruation or a hemorrhoidal bleed, and return it within the time your lab specifies (calprotectin is stable for about 3 days at room temperature and longer refrigerated).
  6. Keep results from the same laboratory where possible: different assays can differ by 30 percent or more at the same true level, which matters when the decision hinges on 150 versus 250.

Diet, lifestyle and natural levers with evidence

What can move FCP once the cause is known. Nothing here replaces finding the cause.

Stop NSAIDs (and, if possible, PPIs) for 2 to 4 weeks before testing

Strong evidence

This is the single most common reason a healthy person returns a borderline calprotectin. In volunteer studies, 2 weeks of standard-dose NSAIDs raised calprotectin above the normal limit in roughly 40 to 70 percent of people, and long-term NSAID users had median levels several times higher than non-users; levels fall back to normal within a few weeks of stopping. PPIs add a smaller, independent rise. Acetaminophen (paracetamol) does not affect the test and is the usual substitute for pain relief in the run-up to a repeat sample.

Do not stop low-dose aspirin prescribed after a heart attack, stent or stroke without asking the prescriber; the test can be interpreted knowing you are on it.

Stopping smoking in Crohn's disease

Strong evidence

Smoking roughly doubles the risk of developing Crohn's disease and worsens its course. In a prospective study of 474 smokers with Crohn's disease, those who quit for over a year had a flare rate about 65 percent lower than continuing smokers, with less need for steroids and immunosuppressants, approaching the rate seen in never-smokers. Lower disease activity translates into lower calprotectin. (In ulcerative colitis smoking has a paradoxical protective association, but quitting is still advised for every other reason.)

Mediterranean-style diet in IBD

Moderate evidence

In the DINE-CD trial, 194 adults with mild to moderate Crohn's disease randomized to a Mediterranean diet or the specific carbohydrate diet for 12 weeks had similar rates of symptomatic remission (about 44 versus 47 percent), and in both groups a minority achieved a fall in calprotectin to under 250 µg/g; the Mediterranean diet was judged easier to follow. A 6-month prospective study of 142 IBD patients found adherence to a Mediterranean diet was associated with reduced calprotectin, lower CRP and lower disease activity scores. Higher fiber and lower ultra-processed food intake are associated with lower flare risk in cohort studies.

During a stricturing Crohn's flare, high-fiber foods can worsen obstruction symptoms; ask your IBD team or dietitian before increasing fiber.

Exclusive enteral nutrition (prescribed liquid diet) in Crohn's disease

Strong evidence

Six to eight weeks of a complete liquid formula diet, with no other food, induces remission in about 70 to 80 percent of children with active Crohn's disease, equivalent to corticosteroids, and produces larger falls in calprotectin and better mucosal healing than steroids in pediatric trials. It is a medically supervised treatment rather than a home lifestyle change, but it is dietary, and it is the first-line induction therapy for pediatric Crohn's disease in European and North American guidelines. Adults respond too, though adherence is harder.

Only under the supervision of an IBD team and dietitian; not a treatment for ulcerative colitis.

Curcumin alongside standard therapy in ulcerative colitis

Moderate evidence

In a 50-patient randomized placebo-controlled trial, adding 3 g a day of curcumin to mesalamine for 4 weeks in people with mild to moderate ulcerative colitis that had not responded to mesalamine alone produced clinical remission in 54 percent versus 0 percent on placebo, with endoscopic improvement in 38 percent versus 0 percent. An earlier 89-patient maintenance trial found 2 g a day of curcumin for 6 months reduced relapse from about 21 percent to 5 percent. A meta-analysis of seven trials supports a roughly three-fold higher remission rate as add-on therapy; calprotectin was not the primary outcome in most trials.

Curcumin can increase bleeding with anticoagulants, trigger gallbladder pain in people with gallstones and rarely cause liver injury at high doses; it is an addition to, not a replacement for, prescribed IBD treatment.

Multi-strain probiotics in ulcerative colitis

Moderate evidence

A high-dose eight-strain probiotic (formerly sold as VSL#3, now marketed under other names) added to standard therapy in mild to moderate ulcerative colitis achieved remission in about 43 percent versus 16 percent on placebo in a 144-patient trial, and E. coli Nissle 1917 maintained remission as well as mesalamine in several trials. Evidence in Crohn's disease is largely negative. Trials reporting calprotectin show modest falls in responders.

Probiotics are generally safe but have caused bloodstream infections in severely immunocompromised people and those with central venous lines; discuss with your IBD team if you are on strong immunosuppression.

When to see a clinician promptly

  • More than 6 bloody stools a day with fever, a heart rate over 90, or feeling faint: possible acute severe colitis, which needs hospital assessment the same day.
  • Severe abdominal pain with a swollen, tense abdomen and vomiting, which can indicate obstruction, perforation or toxic megacolon.
  • Passing large amounts of blood, black tarry stools, or dizziness on standing.
  • A high calprotectin with unexplained weight loss, anemia, a persistent change in bowel habit, or age over 50 with new symptoms, which needs colonoscopy rather than a repeat test.
  • In known IBD, a calprotectin that has risen above 250 µg/g or doubled since the last test, even if you feel well, to review treatment before a flare develops.
  • Fever, severe diarrhea or abdominal pain within a few weeks of antibiotics, which raises the possibility of C. difficile infection.

Frequently asked questions

What is a normal calprotectin level?

Under 50 µg/g of stool in adults, which is the cut-off used in most studies and in the UK NICE guidance for distinguishing IBS from IBD. Some labs use under 100 µg/g. Children under 4 run higher (infants commonly 100 to 500 µg/g) and adults over 60 slightly higher. For people with known IBD, the target is usually under 150 to 250 µg/g, which corresponds to a healed bowel lining rather than to a completely normal result.

Is a calprotectin of 100 bad?

A calprotectin of 100 µg/g is borderline: above the normal limit but well below the levels typical of active IBD. Most labs class 50 to 150 or 200 µg/g as indeterminate. Common explanations are recent ibuprofen, naproxen or aspirin, a proton pump inhibitor, a recent stomach bug, hemorrhoidal bleeding or diverticular disease. The usual step is to stop NSAIDs and repeat in 4 to 6 weeks; about two thirds of repeats come back normal. If it stays raised, or you have bleeding, weight loss or anemia, a colonoscopy is the next step.

Can calprotectin tell the difference between IBS and IBD?

That is its main use. IBS does not cause neutrophils to enter the bowel, so calprotectin stays normal; IBD does, so it rises. In adults with chronic bowel symptoms, a level under 50 µg/g has a sensitivity of about 93 percent and a specificity of about 96 percent for excluding IBD, which means a normal result in someone without red flags makes IBD very unlikely and often avoids colonoscopy. It is less reliable in children, where specificity is lower, and it cannot distinguish Crohn's disease from ulcerative colitis.

Can ibuprofen or omeprazole raise calprotectin?

Yes, both. NSAIDs including ibuprofen, naproxen, diclofenac and low-dose aspirin damage the gut lining; two weeks of regular use pushed calprotectin above normal in around half of healthy volunteers in early studies, typically into the 50 to 200 µg/g range. Proton pump inhibitors such as omeprazole are associated with a smaller rise. Stop NSAIDs for 2 to 4 weeks before a repeat sample (use acetaminophen instead) and tell your clinician about any PPI; do not stop prescribed cardiac aspirin without asking.

What calprotectin level suggests Crohn's disease or ulcerative colitis?

There is no single diagnostic number, because infections and NSAIDs overlap with IBD, but the higher the value, the more likely IBD becomes. Above 150 to 250 µg/g in an adult with chronic symptoms is the usual threshold for colonoscopy; active ulcerative colitis frequently exceeds 1,000 µg/g, and active Crohn's colitis several hundred. Small-bowel Crohn's disease can give lower values. The diagnosis itself is made by colonoscopy with biopsies, not by calprotectin.

How do I collect a stool sample for calprotectin?

Collect a pea-sized amount from the first bowel movement of the day into the container your lab provides, using the scoop in the lid, without letting the stool touch toilet water or urine. Avoid collecting during a menstrual period, after a hemorrhoidal bleed, or after bowel preparation for a colonoscopy. Calprotectin is stable for about 3 days at room temperature and about a week in a refrigerator, so return the sample within the window your lab gives. Diet and fasting do not matter.

Can calprotectin be high without having IBD?

Yes, and in people with borderline values this is the rule rather than the exception. Infectious gastroenteritis, NSAIDs, proton pump inhibitors, diverticulitis, gastrointestinal bleeding, bowel polyps and cancer, ischemic colitis, radiation damage and age under 4 or over 60 all raise it. Calprotectin tells you inflammation is present; identifying the cause needs stool infection tests, a medication review and, when the level stays up, colonoscopy.

How long does it take calprotectin to come down?

After a stomach bug or stopping NSAIDs, levels usually normalize within 4 to 6 weeks, which is why a borderline result is repeated after that interval. In IBD, calprotectin starts to fall within 2 to 4 weeks of effective treatment and typically reaches the under 150 to 250 µg/g target by 8 to 12 weeks as the lining heals; symptoms often improve before the number does, and the number can rise again weeks before a flare is felt.

References

  1. Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel (DG11). National Institute for Health and Care Excellence (NICE) (2013)View source
  2. van Rheenen PF, Van de Vijver E, Fidler V. Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: diagnostic meta-analysis. BMJ (2010)
  3. Turner D, Ricciuto A, Lewis A, et al.. STRIDE-II: an update on the Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) initiative of the International Organization for the Study of IBD (IOIBD). Gastroenterology (2021)
  4. 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)
  5. Tibble JA, Sigthorsson G, Foster R, Scott D, Fagerhol MK, Roseth A, Bjarnason I. High prevalence of NSAID enteropathy as shown by a simple faecal test. Gut (1999)
  6. Poullis A, Foster R, Mendall MA, Shreeve D, Wiener K. Proton pump inhibitors are associated with elevation of faecal calprotectin and may affect specificity. European Journal of Gastroenterology and Hepatology (2003)
  7. Oord T, Hornung N. Fecal calprotectin in healthy children. Scandinavian Journal of Clinical and Laboratory Investigation (2014)
  8. Cosnes J, Beaugerie L, Carbonnel F, Gendre JP. Smoking cessation and the course of Crohn's disease: an intervention study. Gastroenterology (2001)
  9. Lewis JD, Sandler RS, Brotherton C, et al.. A randomized trial comparing the specific carbohydrate diet to a Mediterranean diet in adults with Crohn's disease (DINE-CD). Gastroenterology (2021)
  10. Lang A, Salomon N, Wu JC, et al.. Curcumin in combination with mesalamine induces remission in patients with mild-to-moderate ulcerative colitis in a randomized controlled trial. Clinical Gastroenterology and Hepatology (2015)
  11. Tursi A, Brandimarte G, Papa A, et al.. Treatment of relapsing mild-to-moderate ulcerative colitis with the probiotic VSL#3 as adjunctive to a standard pharmaceutical treatment: a double-blind, randomized, placebo-controlled study. American Journal of Gastroenterology (2010)
  12. Inflammatory bowel disease. Merck Manual Professional Version (2024)

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This page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.