Calprotectin Stool Test: How It Separates IBS From Inflammatory Bowel Disease

A gastroenterology nurse I spoke with keeps a small plastic pot on her desk. Not a souvenir: a reminder of how often a pea-sized stool sample now settles a question that once took a colonoscopy to answer. Search interest in calprotectin has climbed sharply, and as of early 2026 the reason is practical rather than dramatic. Treat-to-target consensus statements from 2021 onward made the fecal calprotectin test a routine monitoring tool, 2023 professional guidelines gave it a formal place in deciding when to scope, and mail-in home kits have put the words “calprotectin result” into thousands of patient portals each week.

That is where the confusion starts. People open an app, see a number next to a color bar, and go looking for what it means. Is 180 dangerous? Did last night’s curry cause it? Does a high reading mean Crohn’s disease?

This explainer walks through what the protein is, what the numbers do and do not say, and how a single stool test became the most useful first step for telling irritable bowel syndrome apart from inflammatory bowel disease.

What is calprotectin, and why does an inflamed gut shed it into stool?

Calprotectin is a calcium-binding protein that makes up roughly 60 percent of the soluble protein inside neutrophils, the white blood cells that arrive first at any site of injury or infection. When the lining of the intestine is inflamed, neutrophils migrate into the bowel wall, die, and release their contents into the gut channel. The protein survives the trip, resists digestion by bacteria, and stays stable in stool for days at room temperature. Measure it, and you are effectively counting how many neutrophils poured into the bowel over the last day or so.

That single mechanism explains the test’s strength and its limits in one breath. The strength: it is a direct marker of gut inflammation, not of mood, diet or the general stress of being unwell. The limit: it cannot say where the inflammation is or what caused it. A bacterial infection, an aspirin-type pain reliever, a bleeding polyp and Crohn’s disease can all push the figure up, because all of them recruit neutrophils.

The laboratory reports calprotectin in micrograms per gram of stool (µg/g). An enzyme immunoassay or an immunoturbidimetric assay, which uses antibodies to capture the protein and measure it optically, produces the number. Different manufacturers use slightly different antibodies and reference ranges, so a result of 90 on one platform is not automatically identical to 90 on another. MedlinePlus describes the test as a way to detect inflammation in the intestines and to help distinguish inflammatory bowel disease from non-inflammatory conditions, which is exactly the framing a reader should keep in mind: it sorts inflamed from not inflamed, and that is the job it does well.

Compare it with a blood test such as C-reactive protein, which rises with inflammation anywhere in the body. Stool calprotectin is gut-specific, and that specificity is why it has displaced blood markers as the first-line screen for bowel inflammation.

What changed recently

Three developments explain why calprotectin moved from a specialist’s tool to a mainstream search term.

First, the 2021 international treat-to-target consensus for inflammatory bowel disease (known as STRIDE-II and published in Gastroenterology) set normal calprotectin as a formal intermediate treatment target, sitting between symptom relief and healing seen on endoscopy. In plain terms, gastroenterologists now aim for a normal stool number, not just a patient who feels better. That turned a one-off diagnostic test into a repeated monitoring test.

Second, clinical practice guidelines published in Gastroenterology in 2023 by the American Gastroenterological Association endorsed a biomarker-first strategy for both ulcerative colitis and Crohn’s disease. The guidance suggests that patients in symptomatic remission with calprotectin below roughly 50 µg/g can usually avoid routine colonoscopy, while values above 150 µg/g in someone with symptoms should trigger an endoscopic look rather than a wait-and-see approach. The 2017 CALM trial, which randomized adults with Crohn’s disease to dose escalation guided by symptoms alone or by symptoms plus biomarkers including calprotectin, provided the trial backbone: the biomarker-guided arm achieved more mucosal healing at one year.

Third, primary care adopted the test. In the United Kingdom, NHS pathways advise general practitioners to use fecal calprotectin in adults with lower bowel symptoms when cancer is not suspected, which cut unnecessary referrals. In the United States, the test is increasingly ordered before referral for the same reason. Mail-in sample kits and patient portals then did the rest.

The practical effect for readers: more people than ever are seeing a calprotectin number before they see a specialist, and many are seeing it repeatedly. The evidence base behind the number is solid at the extremes and genuinely gray in the middle, which is the honest story this article tells.

What does it mean if my calprotectin is high?

A high calprotectin means neutrophils have been active in your gut recently. It does not, on its own, mean you have inflammatory bowel disease, and it does not tell you how serious anything is.

Think of it as smoke rather than fire. Smoke is worth investigating, and the thicker it is, the more likely a real fire. A result of 70 µg/g in a 30-year-old with mild bloating has a different meaning from 800 µg/g in someone passing blood and losing weight. Clinicians read the number alongside the story: how long symptoms have lasted, whether there is blood, night-time diarrhea, weight loss, a family history of IBD, recent travel, recent infections, and which medicines have been taken in the previous month.

The leading causes of a raised value, in roughly descending order of frequency in primary care, are inflammatory bowel disease (Crohn’s disease and ulcerative colitis), gastrointestinal infections, use of non-steroidal anti-inflammatory drugs such as ibuprofen or naproxen, and microscopic colitis. Less common contributors include colorectal polyps and cancer, diverticulitis, celiac disease during active damage, and bowel inflammation from certain cancer immunotherapies. Younger children, especially under four, naturally run higher values.

What happens next depends on the level. A mildly raised result, typically between 50 and 150 µg/g, is often simply repeated after four to six weeks, with any pain-relief medicines paused if a clinician agrees. Around a third of these repeat tests come back normal. A clearly high result, above about 250 µg/g, usually leads to colonoscopy with biopsies, because that is where IBD is confirmed or excluded. Mayo Clinic lists stool studies, blood tests, colonoscopy and imaging as the standard diagnostic sequence for Crohn’s disease, and calprotectin is the stool study that decides how quickly the rest follows.

The one thing a high number should never do is sit unexplained in a portal. It is a prompt for a conversation, not a verdict.

Fecal calprotectin normal range: the cutoffs laboratories actually use

There is no single universal cutoff, which frustrates everyone. Laboratories choose thresholds from the manufacturer’s data, and clinicians adjust interpretation to the setting. The table below summarizes the ranges most commonly quoted in adult practice. Treat the boundaries as zones, not walls.

Calprotectin (µg/g)	How clinicians usually read it	Typical next step
Under 50	Normal; active IBD very unlikely	Look for non-inflammatory causes such as IBS
50–150 (some labs 50–200)	Borderline or gray zone	Review medicines and infections; repeat in 4–6 weeks
150–250	Raised; inflammation probable	Specialist review; colonoscopy often considered
Over 250	Clearly raised; active inflammation likely	Colonoscopy with biopsies, or treatment review if IBD already known

Why these numbers? The 50 µg/g line comes from the original assay validation studies and from the 2010 meta-analysis in the BMJ, which pooled 13 studies and found that a normal calprotectin cut the likelihood of IBD dramatically. In adults, a cutoff of 50 µg/g had a pooled sensitivity of 93 percent and specificity of 96 percent for distinguishing IBD from non-inflammatory conditions. The 250 µg/g line comes from later work comparing stool results with what endoscopists actually saw, where values above that level corresponded well with visibly active disease.

UK primary care pathways widened the normal band to 100 µg/g to reduce false alarms in people with a low pre-test chance of IBD. That is a deliberate trade: a few more missed mild cases in exchange for far fewer unnecessary colonoscopies. US laboratories more often keep 50 as the top of normal. If your report flags a value between 50 and 100, which band you fall into may depend as much on geography as on biology, which is why the number alone should not be read in isolation.

How the calprotectin stool test separates IBS from inflammatory bowel disease

Irritable bowel syndrome and inflammatory bowel disease share letters, symptoms and a cruel capacity to be confused with each other. Both can bring cramping, bloating, urgency and diarrhea. The difference lies in the bowel wall. In IBS the lining looks normal under the microscope; the problem is how the gut moves and how sensitive its nerves are. In IBD, the wall is inflamed and, over time, damaged. Neutrophils are the key witnesses, and calprotectin is their fingerprint.

That is why the test performs so cleanly at separating the two. Someone with IBS has few neutrophils in the bowel lining, so stool calprotectin stays low, usually well under 50 µg/g. Someone with active ulcerative colitis or Crohn’s disease sheds neutrophils continuously, and the figure climbs into the hundreds or thousands. The BMJ meta-analysis estimated that in adults, screening with calprotectin would reduce the number of unnecessary colonoscopies by 67 percent, at the cost of delaying diagnosis in about 6 percent of people with IBD who initially tested normal.

Notice what the test cannot do. It cannot diagnose IBS, because IBS is defined by symptom patterns and the absence of another explanation; the Rome criteria used worldwide rely on abdominal pain linked to bowel habit changes over at least three months. A normal calprotectin supports that diagnosis by making inflammation improbable, but it is one piece of evidence beside a careful history, basic blood tests and celiac screening. The NHS lists these same steps in its guidance on diagnosing IBS.

Nor can calprotectin distinguish Crohn’s disease from ulcerative colitis, or IBD from an infection. Those distinctions need stool cultures, colonoscopy and biopsies. The honest summary: calprotectin is the sorting hat at the door, excellent at deciding who needs the full examination, and not designed to name the diagnosis itself.

What level of calprotectin indicates Crohn's disease or ulcerative colitis?

No number diagnoses Crohn’s disease, and anyone who tells you a specific figure does is overselling the test. What the number can do is estimate how likely active IBD is and, once IBD is confirmed, how active it currently is.

At diagnosis, people with untreated ulcerative colitis or colonic Crohn’s disease often present with calprotectin well above 250 µg/g, frequently above 500 and sometimes in the thousands. Values that high in a person with persistent diarrhea, blood in the stool or weight loss make IBD the leading possibility, and colonoscopy follows promptly. Cleveland Clinic’s overviews of Crohn’s disease and ulcerative colitis both describe stool tests as part of the workup, with endoscopy and biopsy as the confirming steps.

Calprotectin levels in Crohn’s disease are less reliable than in ulcerative colitis, and this matters. Ulcerative colitis always involves the colon and rectum, close to where stool forms, so neutrophils reach the sample easily. Crohn’s disease can be confined to the small intestine, especially the terminal ileum, where inflammation may be patchy and the released protein partly degraded before it reaches the colon. Studies comparing stool results with endoscopy have found that calprotectin correlates with visible disease activity strongly in ulcerative colitis and colonic Crohn’s, but only moderately in isolated small-bowel Crohn’s. A normal result in someone with convincing symptoms of small-bowel disease therefore does not close the case; imaging of the small intestine may still be needed.

Once IBD is established, the thresholds shift purpose. Values under 50 to 100 µg/g during treatment suggest the lining has healed; values rising above 150 to 250 µg/g, even before symptoms return, predict a flare over the following months in several cohort studies. That predictive power is what the treat-to-target era is built on. It is also why your gastroenterologist may ask for a stool sample when you feel perfectly well.

What level of calprotectin indicates IBS, and can the test be used for IBS?

People with irritable bowel syndrome typically have calprotectin below 50 µg/g, and most sit comfortably under 30. Several studies that measured the protein in confirmed IBS have found median values in the teens, overlapping completely with healthy volunteers. That is the finding you would expect from a condition with no neutrophil activity in the bowel wall.

So is there a calprotectin test for IBS? Not in the sense of a positive result. The test is used in the opposite direction: a normal value lowers the probability of IBD so much that, together with normal blood counts, a negative celiac screen and no alarm features, a clinician can diagnose IBS with reasonable confidence and move on to managing it. For a 28-year-old with two years of bloating and alternating bowel habit, a calprotectin of 22 µg/g is reassuring in a way few other single tests can match.

Two caveats keep this honest. First, a small group of people with IBS-type symptoms have calprotectin in the 50 to 100 range with no inflammatory disease ever found. Mild, non-specific elevation can come from a recent viral illness, over-the-counter pain relievers, or simply the day-to-day scatter of the assay, which can be 30 percent or more between samples from the same person. Repeating the test usually resolves it. Second, a normal result does not rule out other non-inflammatory causes of symptoms such as bile acid diarrhea, small-intestinal bacterial overgrowth or lactose intolerance; it simply removes IBD from the front of the queue.

The practical message: if your calprotectin is normal and your symptoms fit the IBS pattern, the evidence supports treating the IBS rather than chasing a colonoscopy. Age matters, though. Over 50, or at any age with bleeding or weight loss, the test does not replace cancer screening, because colorectal cancer can produce a normal or only mildly raised calprotectin.

Can food cause high calprotectin?

This is one of the most searched questions about the test, and the answer is more reassuring than the viral posts suggest. Ordinary food does not raise calprotectin in a meaningful way. Spicy meals, dairy, gluten in someone without celiac disease, large amounts of fiber, coffee and sugar alcohols can all trigger cramping, gas and loose stools, but they do so by changing gut motility, fluid secretion and gas production, not by summoning neutrophils into the bowel wall. The stool may look alarming while the inflammation marker stays flat.

What the evidence actually shows: small observational studies have compared calprotectin before and after dietary changes in healthy people and in IBS, and the differences have been within the test’s normal day-to-day variation. One exception deserves mention. In people with celiac disease, eating gluten damages the small-intestinal lining and can modestly raise calprotectin until the diet is corrected; that is disease activity, not a food effect in a healthy gut. Heavy alcohol intake has been linked to small rises in a few studies, plausibly through direct irritation of the lining, but the data are limited and inconsistent.

Food-borne infection is a different matter entirely. Bacteria such as Campylobacter, Salmonella and Shigella, and parasites such as Giardia, inflame the gut and can push calprotectin into the hundreds for a week or more after the illness. So the honest version of “my food caused it” is “something I ate gave me an infection, and the infection caused it.” This is why clinicians often send a stool culture alongside or before a calprotectin test when diarrhea began abruptly.

Two practical implications follow. You do not need to change your diet before the test, and doing so will not produce a false normal if you have IBD. And if you have been told your calprotectin is high, cutting out foods will not bring it down; finding the inflammatory cause will.

High calprotectin causes beyond IBD: medicines, infections and age

Because the test measures neutrophils rather than a specific disease, a thoughtful reading of any raised result starts by asking what else could have recruited those cells. The list is short but important.

• Non-steroidal anti-inflammatory drugs. Ibuprofen, naproxen, diclofenac and high-dose aspirin cause tiny erosions throughout the gut in many regular users. Studies in healthy volunteers have shown calprotectin rising within days of starting these medicines and settling a few weeks after stopping. Some laboratories specifically ask about NSAID use on the request form.
• Proton pump inhibitors. Acid-suppressing medicines such as omeprazole have been linked to modestly higher values in several observational studies, possibly through changes in gut bacteria. The effect is usually mild.
• Infections. Bacterial gastroenteritis, Clostridioides difficile infection and some parasites produce marked elevations, sometimes rivaling IBD. Values generally normalize within four to eight weeks of recovery.
• Structural lesions. Colorectal polyps, colorectal cancer and diverticulitis can raise calprotectin, though cancer often does so only modestly, which is why the test is not a cancer screen.
• Other inflammatory conditions. Microscopic colitis, active celiac disease, radiation injury and colitis caused by checkpoint-inhibitor cancer immunotherapy all count.
• Age. Infants and toddlers run naturally higher levels; a value of 150 µg/g in a one-year-old may be entirely normal. In adults over 60, values drift upward slightly, and polyps and diverticular disease become more common contributors.

None of this means you should stop a prescribed medicine to “clean up” a result. If a clinician suspects a pain reliever is the culprit, they will decide whether a pause is safe and for how long before repeating the test. Changing or stopping a prescription on your own, particularly aspirin taken for heart protection, carries risks that outweigh a clearer lab value. The role of this list is to help you give a complete medicine and illness history, which is often the fastest route to an explanation.

How to collect a calprotectin stool sample so the result is reliable

The test is only as good as the sample. A few details, most of them simple, make a real difference to whether the number reflects your gut or an artifact of the bathroom.

Collect from a bowel movement that has not touched toilet water. Most kits include a paper collection sheet or a disposable tray that sits across the bowl; some people use a clean, dry container. Water dilutes the sample and can distort the result. Urine contamination matters less but is best avoided. Using the small spoon attached to the lid of the pot, transfer a pea-sized amount, roughly the size of a hazelnut if the stool is loose. Laboratories need only a gram or so; overfilling can make the pot leak and the lab reject it.

Timing is worth a sentence. Calprotectin concentration varies through the day, and several studies have found the first bowel movement of the morning gives the most consistent reading. If you are being monitored over months, collecting at the same time of day each round reduces noise. Day-to-day variability within one person can be substantial, which is one reason a single borderline value is usually repeated rather than acted on.

Once collected, the protein is stable for about three days at room temperature and considerably longer in a refrigerator, so a sample taken on a Friday can reach the lab on Monday. Follow the kit’s specific storage instructions, as some newer extraction devices differ.

Things that do not matter: what you ate yesterday, whether you are fasting, and whether the stool was formed or loose. Things that do matter and should be mentioned to the ordering clinician: a bout of diarrhea in the past month, recent antibiotics, any pain-relief medicines, and heavy menstrual bleeding, since blood in the sample can nudge values upward. If you have active bleeding from hemorrhoids, say so; a few studies suggest it can modestly raise the figure.

What the evidence actually says, and how strong it is

Grading the evidence behind calprotectin is unusually satisfying, because the test has been studied against the gold standard, colonoscopy with biopsy, thousands of times.

Strong evidence (systematic reviews of diagnostic accuracy studies). For distinguishing IBD from non-inflammatory conditions in adults referred to specialists, the 2010 BMJ meta-analysis of 13 studies found pooled sensitivity of 93 percent and specificity of 96 percent at the 50 µg/g threshold. Later reviews, including those underpinning UK diagnostic guidance, have confirmed similar figures across different assays. This is about as solid as diagnostic evidence gets.

Moderate evidence (prospective cohorts and one randomized trial). For monitoring established IBD, multiple cohort studies show that calprotectin tracks endoscopic activity, with correlation strongest in ulcerative colitis. The CALM randomized trial in Crohn’s disease showed that adjusting treatment to biomarkers including calprotectin, rather than symptoms alone, increased mucosal healing at one year. This is the basis for current treat-to-target recommendations, which guideline panels rate as conditional recommendations based on moderate-certainty evidence.

Weaker evidence (observational data, expert opinion). Performance in primary care is less certain because the people tested there have a lower prior probability of IBD, so false positives are relatively more common; studies suggest specificity of 70 to 80 percent at a 50 µg/g cutoff in that setting, which is why higher thresholds and repeat testing are used. Performance in isolated small-bowel Crohn’s disease is only moderate. Claims about food effects, stress effects and precise cutoffs for predicting flares rest on small studies and vary between them.

Where evidence is lacking. There is no high-quality evidence that calprotectin is useful as a general wellness or microbiome screen in people without symptoms, and no evidence supports buying tests online to self-monitor without clinical interpretation. The test earns its reputation when it answers a specific clinical question, and loses it when used as a curiosity.

Calprotectin for monitoring IBD: why your gastroenterologist keeps asking for stool

If you already have ulcerative colitis or Crohn’s disease, the stool pot becomes a routine companion. The reason is a mismatch that frustrated patients and doctors for decades: how someone feels does not reliably reflect what the bowel lining looks like. Up to a third of people with IBD who feel well still have active inflammation visible on colonoscopy, and that silent inflammation drives long-term complications such as strictures, hospital admissions and surgery.

Calprotectin bridges the gap without a scope. Cohort studies following people in symptomatic remission have found that those with values under about 100 µg/g usually stayed well over the next year, while those with values above 250 µg/g had a markedly higher chance of a flare within months. Clinicians use this in several ways. A rising trend on a stable treatment may prompt earlier review or a check for adherence. A normal value in someone with mild symptoms can support watchful waiting rather than escalation. After a change in therapy, a falling value is early objective evidence the treatment is working, often weeks before an endoscopy would be scheduled.

Trend matters more than any single reading. Because of day-to-day variability, a jump from 60 to 110 is often noise; a steady climb across three samples is a signal. Many specialists ask for a repeat sample before acting on one unexpected result.

The frequency of testing varies with disease stability, typically every three to six months in remission and more often after a treatment change. Any adjustment to medicines that follows a result is a decision for the prescribing clinician, weighing the stool value against symptoms, blood tests, imaging and the person’s own priorities. The test informs that conversation; it does not replace it. For someone living with IBD, the most useful habit is simply to know your own baseline number and the direction it is moving.

Calprotectin in children, older adults and during pregnancy

Age changes what a number means, and the test is used across the whole lifespan.

In children, calprotectin has become the preferred first test for suspected IBD, partly because colonoscopy requires general anesthesia in the young. The BMJ meta-analysis found sensitivity of 92 percent in pediatric studies but lower specificity of 76 percent, meaning children more often have raised values without IBD. Healthy infants and toddlers have higher baseline levels, likely reflecting an immature gut barrier and a developing microbiome; values that would alarm in an adult can be normal before age four. Pediatric gastroenterologists interpret results with age-adjusted ranges and lean more heavily on the clinical picture, growth charts and blood tests. Johns Hopkins and other pediatric centers describe stool studies as part of the standard evaluation of childhood IBD alongside blood work and endoscopy.

In older adults, the differential diagnosis broadens. Diverticular disease, polyps, colorectal cancer, ischemic injury to the bowel and microscopic colitis all become more common and all can raise calprotectin. A raised value after age 50 is therefore less specific for IBD, and a normal value is less reassuring about cancer. Screening colonoscopy or stool-based cancer screening should continue on schedule regardless of the calprotectin result. The CDC recommends regular colorectal cancer screening for adults aged 45 to 75, and no inflammation marker substitutes for it.

During pregnancy, calprotectin is particularly valuable because colonoscopy is avoided where possible and blood markers such as C-reactive protein shift with pregnancy itself. Studies in pregnant people with IBD suggest the stool test still tracks disease activity reliably. For anyone planning or in a pregnancy with IBD, the interplay between disease control, medicines and the pregnancy is managed jointly by gastroenterology and obstetric teams, and stool monitoring is one of the safer tools they lean on.

Common myths about calprotectin, and what the evidence says instead

Viral posts and forum threads have attached several confident claims to this test. Most do not survive contact with the data.

Myth: “Any calprotectin above 50 means IBD.” The 50 µg/g line marks the top of normal, not the bottom of disease. In primary care, most values between 50 and 150 do not turn out to be IBD; infections, pain relievers and assay variability account for many. Guidelines treat this band as a reason to repeat, not to diagnose.

Myth: “A normal result rules out everything.” It makes active IBD unlikely. It does not exclude small-bowel Crohn’s disease, colorectal cancer, celiac disease in remission, bile acid diarrhea or any of the non-inflammatory causes of symptoms. It is a strong piece of evidence, not a full stop.

Myth: “Stress or anxiety raises calprotectin.” Stress can worsen IBS symptoms through the gut-brain connection, but it does not recruit neutrophils into the bowel wall. Studies have not shown meaningful calprotectin rises from psychological stress alone. If your value is high, look for a physical cause.

Myth: “You can lower it with an anti-inflammatory diet or supplements.” No randomized trial shows that any diet, probiotic or supplement reduces calprotectin in people without IBD, and in IBD, diet is at most an adjunct to prescribed treatment. A falling value reflects controlled inflammation, not a product.

Myth: “Calprotectin tells you which type of IBD you have.” It cannot distinguish Crohn’s disease from ulcerative colitis, or either from an infectious colitis. Only colonoscopy with biopsies and sometimes imaging can.

Myth: “Home test kits sold online give you a diagnosis.” Direct-to-consumer kits measure the same protein, but a number without clinical context creates more anxiety than clarity. The value of the test lies in who interprets it and what they do next.

When to see a doctor

Calprotectin is a test ordered and interpreted by a clinician, so the first answer is simple: if you have persistent bowel symptoms, see your doctor and let them decide whether the test is the right next step. Some situations should not wait for a routine appointment.

Seek urgent medical attention, the same day, if you have:

• Blood in your stool that is more than streaks on the paper, or black, tarry stools
• Severe abdominal pain, especially with a fever or a swollen, tender abdomen
• Diarrhea with signs of dehydration: dizziness on standing, very little urine, a racing heartbeat
• Persistent vomiting or inability to keep fluids down
• Diarrhea of more than six to eight episodes a day lasting several days, particularly if you already have IBD

Book a prompt, non-emergency appointment if you notice unintentional weight loss, diarrhea that wakes you at night, symptoms lasting longer than four weeks, a new change in bowel habit after age 45, anemia on a routine blood test, or a strong family history of IBD or colorectal cancer. These are the features that move a clinician from “probably IBS” to “we need to look,” and calprotectin is often the test they reach for first.

If you already have a result, bring the number and the date. A high value needs a plan, usually further testing; a borderline value usually needs a repeat and a medicine review; a normal value with ongoing symptoms still deserves attention, because IBS and other non-inflammatory conditions are treatable in their own right. Never stop or change a prescribed medicine to influence a repeat result unless the prescribing clinician advises it. The NHS, Mayo Clinic and Cleveland Clinic all list these alarm features in their patient guidance on IBS and IBD, and they match what gastroenterologists use at the front door.

Frequently asked questions

What does it mean if my calprotectin is high?

A high calprotectin means white blood cells called neutrophils have recently been active in your gut, which signals inflammation but not a specific diagnosis. Inflammatory bowel disease, gut infections, pain relievers such as ibuprofen, polyps and microscopic colitis can all raise it. Your clinician will interpret the number alongside your symptoms and history; values above about 250 µg/g usually lead to colonoscopy, while mild rises are often repeated after a few weeks.

Can food cause high calprotectin?

Ordinary food does not raise calprotectin in a meaningful way. Spicy meals, dairy and fiber can upset the gut without recruiting neutrophils, so the marker stays flat. Exceptions are indirect: gluten in someone with celiac disease, and food-borne infections, which inflame the bowel and can push values into the hundreds for weeks. You do not need to change your diet before the test, and diet changes will not fix a genuinely high result.

What level of calprotectin indicates Crohn's disease?

No level diagnoses Crohn’s disease; only colonoscopy with biopsies and sometimes imaging can confirm it. Untreated Crohn’s affecting the colon often produces values above 250 µg/g and frequently above 500. Disease confined to the small intestine can give lower or even normal readings, because inflammation is patchy and far from where stool forms. A high number raises the probability and speeds referral; a normal one lowers it without fully excluding small-bowel disease.

What level of calprotectin indicates IBS?

People with irritable bowel syndrome usually have calprotectin below 50 µg/g, and most sit under 30, overlapping with healthy volunteers. The test does not produce a positive result for IBS; it supports the diagnosis by making inflammatory bowel disease unlikely. Combined with normal blood tests, a negative celiac screen and the absence of alarm features such as bleeding or weight loss, a normal value lets a clinician diagnose and manage IBS with confidence.

What is the fecal calprotectin normal range?

Most laboratories report under 50 µg/g as normal for adults, though some primary care pathways treat up to 100 µg/g as normal to reduce false alarms. Values from 50 to 150 are considered borderline, 150 to 250 raised, and above 250 clearly elevated. Ranges differ between assay manufacturers, and infants and toddlers have naturally higher levels, so always read the reference range printed on your own report and discuss it with the ordering clinician.

What are the most common high calprotectin causes besides IBD?

The leading non-IBD causes are gut infections such as Campylobacter, Salmonella or Clostridioides difficile, and regular use of non-steroidal anti-inflammatory drugs including ibuprofen and naproxen. Proton pump inhibitors, colorectal polyps and cancer, diverticulitis, microscopic colitis, active celiac disease and immunotherapy-related colitis also raise it. Young age and heavy bleeding into the stool can nudge values upward. A clinician reviews these before deciding on further tests.

Is a calprotectin test for IBS worth doing if I have no alarm symptoms?

Often yes, particularly in adults under 50 with chronic diarrhea or mixed bowel habits, because a normal result makes inflammatory bowel disease unlikely and can avoid an unnecessary colonoscopy. Research estimates calprotectin screening reduces unneeded scopes by about two-thirds. It is less useful when symptoms are mainly constipation, and it is never a substitute for colorectal cancer screening. Whether to order it is a decision for your clinician.

How do calprotectin levels in Crohn's disease guide treatment once diagnosed?

After diagnosis, the test shifts from detection to monitoring. Values falling below roughly 100 µg/g on treatment suggest the lining is healing, while a steady rise above 150 to 250 µg/g predicts a flare in the coming months. Current guidelines use normal calprotectin as a treatment target, and a randomized trial found biomarker-guided adjustment improved mucosal healing. Any change to medicines based on the result belongs to the prescribing gastroenterologist.

Can I repeat the test at home, and how soon?

Many clinics provide mail-in kits, and repeat testing is common. For a borderline first result, clinicians usually wait four to six weeks, ideally after any infection has cleared and after reviewing pain-relief medicines. For monitoring established IBD, testing every three to six months in remission is typical, more often after a treatment change. Collecting the first morning stool, avoiding toilet water and sending a pea-sized sample keep results consistent.

Does a normal calprotectin mean I do not need a colonoscopy?

It makes colonoscopy for suspected IBD much less likely to be needed, which is the test’s main purpose. It does not remove the need for colonoscopy in other situations: age-appropriate colorectal cancer screening, rectal bleeding, unexplained anemia, weight loss, or symptoms suggesting small-bowel Crohn’s disease, where calprotectin can be normal. Your clinician weighs the stool result against these factors before deciding.

References

• MedlinePlus: Calprotectin Stool Test
• NHS: Irritable bowel syndrome (IBS)
• CDC: Colorectal cancer screening

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.