Can IBS cause high fecal calprotectin?

IBS on its own should not raise fecal calprotectin, because IBS does not draw neutrophils into the bowel wall. When someone with IBS-type symptoms has a raised result, the clinician looks for another cause, such as infection, NSAID use, IBD, polyps or diverticulitis.

What does a borderline fecal calprotectin mean?

A borderline result, often 100 to 250 µg/g, means mild inflammation is possible. So is a temporary rise from an infection or a painkiller. It is usually repeated about 2 to 4 weeks later before anyone treats it as disease (see the cutoff table above). Bleeding, weight loss or anemia need prompt review instead of a wait.

Can ibuprofen or other NSAIDs raise fecal calprotectin?

Yes. Regular use of NSAIDs such as ibuprofen, naproxen or aspirin can inflame the bowel lining and raise fecal calprotectin. Tell whoever ordered the test about every painkiller you took in the weeks before the sample, and ask whether to pause it before a repeat test. If you take low-dose aspirin or another medicine prescribed to protect your heart or prevent stroke, do not stop it for a stool test unless the doctor who prescribed it tells you to.

Does a normal fecal calprotectin rule out colon cancer?

No. Fecal calprotectin measures inflammation, and some bowel cancers do not raise it. Blood in the stool, unexplained weight loss, anemia, a lasting change in bowel habit or a family history of bowel cancer need prompt medical review whatever the calprotectin result. Colonoscopy or FIT (a stool test for blood) is used to check for cancer.

Fecal Calprotectin: what it measures and how to read it

Quick answer

Fecal calprotectin is a stool test for gut inflammation. In adults with gut symptoms, a result below about 50 µg/g (micrograms per gram of stool) makes inflammatory bowel disease (IBD, which includes Crohn's disease and ulcerative colitis) unlikely ¹². A functional cause (real symptoms with no visible inflammation or damage), such as irritable bowel syndrome (IBS), then becomes more likely. A borderline result, often 100 to 250 µg/g, is usually repeated a few weeks later. That only applies if you have none of the warning signs, such as bleeding, weight loss or anemia, which need prompt review instead of a wait. A result over about 250 µg/g that stays high on the repeat usually leads to an urgent specialist referral ⁶. A high result shows the bowel is inflamed but cannot say why, because infections, NSAID painkillers such as ibuprofen, and bowel cancer can raise it too ³⁷.

The distinctions

01
A low result rules IBD out; a high result does not rule it in
In adults, fecal calprotectin picks up about 93 of every 100 IBD cases, so a result under about 50 µg/g makes IBD unlikely. A high result means the bowel is inflamed, and the cause could just as easily be infection, NSAIDs, polyps, cancer or diverticulitis as IBD.

In adults with gut symptoms, a fecal calprotectin under about 50 µg/g makes inflammatory bowel disease (IBD, the group that includes Crohn's disease and ulcerative colitis) unlikely. That low result is the most reliable thing the test can tell you, because in adults it picks up about 93 of every 100 IBD cases ². Clinicians usually repeat a higher result before reading it as disease. In the York care pathway, used in parts of the NHS, any result of 100 µg/g or more is repeated. If the repeat is over 250 µg/g, the patient is sent urgently to a gastroenterologist (a gut specialist) ⁶. A high fecal calprotectin means the bowel wall is inflamed, and the cause of that inflammation still has to be found.

Beyond the cutoffs

01Fecal calprotectin comes from neutrophils, the white blood cells that gather wherever tissue is inflamed. The stool level shows how many neutrophils have moved into the bowel wall ³.
02In adults, testing calprotectin first was estimated to cut the number of people needing endoscopy (a camera test of the bowel) by about 67% ².
03A normal fecal calprotectin does not rule out bowel cancer ⁷. Bowel cancer is checked with tests made for it, such as colonoscopy or FIT (fecal immunochemical test, a stool test for blood).
04Healthy children under about age 4 tend to have higher calprotectin than adults, so adult cutoffs can wrongly flag them.
05People who already have ulcerative colitis are monitored against a different cutoff, 150 µg/g, set by the American Gastroenterological Association ⁴.

What fecal calprotectin measures

Calprotectin is a protein found mostly inside neutrophils, where it makes up roughly 60% of the soluble protein in the cell ³. Neutrophils are the first white blood cells to arrive at inflamed tissue. When they pour into an inflamed bowel wall, calprotectin is shed into the gut and leaves the body in stool. Calprotectin stays stable in stool for at least a week at room temperature. That means the amount a lab finds rises with the amount of neutrophil-driven inflammation in the gut ³.

How calprotectin travels from an inflamed bowel to the lab

Something inflames the gut lining

IBD, an infection, NSAID damage, a polyp or a tumor can each start an inflammatory signal in the bowel wall.

Neutrophils move in

Neutrophils leave the blood and gather in the inflamed bowel wall and lining.

Calprotectin is shed into the gut

As neutrophils gather and break down in the bowel wall, calprotectin spills into the gut ³.

The lab measures what reaches the stool

Calprotectin survives the trip through the bowel, so the stool level tracks how much neutrophil activity is going on. The level cannot show which of the causes in step 1 started it.

Mechanism as described by Bjarnason, Gastroenterology & Hepatology 2017 ³.

Fecal lactoferrin is another neutrophil protein measured in stool, and it is read in a similar way. Its own page covers how the two compare in practice. For inflammation measured in blood, see CRP and inflammation markers explained.

Normal, borderline and high: the cutoffs

Where an example result of 120 µg/g fallsµg/g

120 µg/gborderline · example value in the repeat-test band

Normal0–50Grey zone50–100Repeat test100–250Raised250–500

A fecal calprotectin of 120 µg/g means mild gut inflammation is possible but unproven. In the York pathway, a result like this is repeated, typically 2 to 4 weeks later. If the repeat stays between 100 and 250 µg/g, it leads to a routine specialist referral ⁶. Warning signs such as bleeding, weight loss or anemia need prompt review instead of a wait.

Under 50 µg/g is the cutoff assessed in UK NICE guidance (DG11) ¹. The 100 and 250 µg/g bands come from the York faecal calprotectin care pathway ⁶, and many labs use 200 in place of 250. Cutoffs vary by test kit (assay) and by local pathway, so check the range printed on your report. Illustrative example value.

Result (µg/g)	How it is usually read	What usually happens next
Under 50	Normal ¹	In adults with symptoms, IBD becomes unlikely. The clinician considers functional causes such as IBS.
50 to 99	Normal or borderline, depending on the lab	In the York pathway this is still managed as likely IBS. The patient is reviewed and referred if symptoms continue ⁶.
100 to 250	Borderline	Usually repeated about 2 to 4 weeks later. If the repeat stays in this band, the next step is a routine referral to a gastroenterologist ⁶. If you take NSAIDs, ask the prescriber whether to pause them first.
Over 250 (some labs use 200)	Raised	If a repeat test confirms it, an urgent referral follows, often straight to colonoscopy (a camera test of the whole large bowel) ⁶.
Over 150, in someone already diagnosed with ulcerative colitis	Monitoring cutoff from the American Gastroenterological Association (AGA), a separate use	Supports active disease when symptoms are moderate to severe ⁴.

Fecal calprotectin has no separate 'optimal' target. The lab's upper limit of normal, usually 50 µg/g, works as the target, and a lower result has no extra meaning. Different test kits read the same stool slightly differently, so a value near a cutoff can be labeled normal at one lab and borderline at another. Reference ranges explained covers why labs differ.

Young children run higher

Healthy infants and children under about age 4 tend to have higher fecal calprotectin than adults. This helps explain the BMJ meta-analysis results. Calprotectin's specificity (how often people without IBD correctly get a normal result) was 0.76 in children and teenagers, compared with 0.96 in adults ². In plain terms, more healthy children got a falsely raised result. A pediatrician reads a young child's result against age-adjusted expectations.

Why a low result is the one to trust

A 2010 BMJ meta-analysis (a study that combines the results of earlier studies) pooled 6 studies covering 670 adults with suspected IBD ². Across those studies, fecal calprotectin had a sensitivity of 0.93 and a specificity of 0.96. Sensitivity of 0.93 means the test flagged 93 of every 100 adults who turned out to have IBD, so a normal result leaves little room for missed disease. Specificity of 0.96 means 96 of every 100 adults without IBD got a normal result. In 7 studies covering 371 children and teenagers, sensitivity was 0.92 and specificity was 0.76 ².

67%fewer adults were estimated to need endoscopy when calprotectin was used to screen firstAbout 6% of adults would have had a delayed diagnosis because their calprotectin came back normal even though they had IBD (a false negative) ²

Testing for faecal calprotectin is a useful screening tool for identifying patients who are most likely to need endoscopy for suspected inflammatory bowel disease.van Rheenen PF, Van de Vijver E, Fidler V. BMJ 2010;341:c3369 ²

The UK's National Institute for Health and Care Excellence (NICE) recommends fecal calprotectin to help clinicians tell IBD from IBS. The recommendation covers adults with recent-onset lower gut symptoms who are being considered for specialist assessment, as long as cancer is not suspected. It also covers children with suspected IBD who have been referred to a specialist ¹. In the US, the American College of Gastroenterology recommends fecal calprotectin or fecal lactoferrin, plus CRP, to rule out IBD in people with suspected IBS and diarrhea who have no warning signs ⁸. IBS causes real symptoms but does not draw neutrophils into the bowel wall, so IBS on its own should not raise calprotectin. A normal result in someone with typical IBS symptoms supports the IBS diagnosis. Sometimes calprotectin is normal but symptoms such as chronic diarrhea or greasy stools continue. Other stool tests, such as fecal elastase-1, can then check for other causes. The gut hub covers the rest.

What else raises calprotectin

Fecal calprotectin rises with neutrophil-driven inflammation anywhere in the gut, and IBD is only one cause. Bjarnason's review notes that almost every disease of the colon, and many diseases of the small bowel, come with inflammation ³. Before a high result is read as Crohn's disease or ulcerative colitis, the clinician has to rule out the other causes in the table.

Cause	Why it raises calprotectin
Gut infection (bacterial or viral gastroenteritis)	Infection draws neutrophils into the lining until it clears. Some food infections give very high readings ³.
Regular NSAID use (ibuprofen, naproxen, aspirin) and alcohol	Both can cause low-grade inflammation of the bowel lining ³.
Colorectal cancer and large polyps	These can raise calprotectin, but a normal result does not fully rule them out ⁷.
Diverticulitis	Inflamed pouches in the colon wall attract neutrophils.
Microscopic colitis	Inflammation that is visible only under a microscope can still raise calprotectin.

Calprotectin, FIT, CRP and lactoferrin

Calprotectin finds inflammation and FIT finds blood, so a normal calprotectin does not rule out bowel cancer. NICE limits calprotectin to people in whom cancer is not suspected ¹⁵.

	Fecal calprotectin	FIT (fecal immunochemical test)	CRP (C-reactive protein)	Fecal lactoferrin
What it measures	Neutrophil protein in stool	Human blood in stool	Liver-made inflammation protein in blood	Another neutrophil protein in stool
Sample	Stool	Stool	Blood	Stool
Where it is most useful	Telling IBD from IBS; monitoring known IBD	Bowel cancer screening and triage	Body-wide inflammation	Gut inflammation; similar job to calprotectin
Main blind spot	Cannot name the cause; can miss cancer	Cannot measure inflammation	Can be normal in active IBD, especially ulcerative colitis	Less widely used and studied
Own page	This page	FIT	CRP	Lactoferrin

Blood in your stool or bleeding from the bottom
Diarrhea that wakes you at night to pass stool
Weight loss you cannot explain
Fever
Anemia, meaning low hemoglobin or low ferritin
A lasting change in your bowel habit, especially if you are over 45
A lump in your belly or back passage
A family history of bowel cancer or IBD

For more on low blood counts and iron, see anemia and iron deficiency. Microbiome panels often include stool markers such as zonulin and secretory IgA. Neither has the guideline backing that fecal calprotectin has.

If you already have ulcerative colitis

The American Gastroenterological Association (AGA) uses a fecal calprotectin cutoff of 150 µg/g for people already diagnosed with ulcerative colitis. In someone whose symptoms are in remission, a result below 150 µg/g helps rule out active inflammation. In someone with moderate to severe symptoms, a result above 150 µg/g supports active disease without routine endoscopy ⁴. The 150 µg/g cutoff is for monitoring known disease. It does not replace the bands used when IBD is first suspected.

How the test works in practice

No fasting is needed. You collect a small stool sample at home with the scoop and pot the lab provides, then return it as instructed. Some labs ask for the first stool of the day.
Fecal calprotectin is a separate stool order. It is not part of routine blood work or a standard stool culture.
Results usually come back within a few days. In the US, insurance often covers the test when a clinician orders it for symptoms, but coverage and cash prices vary, so ask the lab or your plan.
Fecal calprotectin is not a screening test for people without symptoms, and relatives are not routinely tested. A family history of bowel cancer usually means colonoscopy, often starting earlier than average. Ask your clinician when to begin (see bowel cancer screening).
Repeat timing depends on the reason for the test. A borderline result is usually repeated within a few weeks; in the York pathway the typical repeat came 18 days after the first ⁶. People with known IBD are retested on a schedule set by their specialist.

For more on stool and blood markers of gut health, see the gut hub, the inflammation hub and how to read any lab result.

Link · NICEFaecal calprotectin diagnostic tests for inflammatory diseases of the bowel (DG11)The UK guidance on using calprotectin to separate IBD from IBS in adults and children.nice.org.uk

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Citations

Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.