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Blood Test Tracker

Calprotectin, Fecal

A protein released by white blood cells into the gut. Higher levels in a stool sample can be a sign of inflammation in the intestines.

AI-verified against cited sources. Awaiting expert reviewAlso called FCPLOINC 38445-3

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What it is

Calprotectin is a protein made mostly by white blood cells called neutrophils. When the lining of the intestines is inflamed, these cells move into the gut, and some of the calprotectin ends up in the stool. The test measures it in a small stool sample that you collect at home or in a clinic. It helps show whether symptoms such as ongoing diarrhea and belly pain come with inflammation in the intestines. It cannot show the cause by itself.

Why it matters

A low level makes inflammation in the intestines less likely. That is why this test is often used to help tell inflammatory bowel disease (IBD) from irritable bowel syndrome (IBS), where the gut lining is not inflamed. In people who already have IBD, it can help show whether inflammation is settling. It is not specific, though. Infections, some medicines and other conditions can raise it too, and it can be normal even when inflammation is present.

If it’s high

A higher result means inflammation in the intestines is more likely. It does not say what is causing it. Mayo Clinic Laboratories and Labcorp both call results under 50 µg/g normal, 50 to 120 µg/g borderline and above 120 µg/g abnormal. Your clinician can decide whether to repeat the test in a few weeks or look inside the bowel with a colonoscopy.

Common causes

  • NSAID pain relievers, such as ibuprofen or naproxen, and proton pump inhibitors
  • Intestinal infections, including some kinds of food poisoning
  • Diverticular disease
  • Untreated celiac disease
  • Inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis
  • Colorectal cancer

What can help

  • Ask your clinician whether a medicine you take, such as an NSAID or an acid reducer, could explain the result
  • Ask whether the test should be repeated in a few weeks
  • Ask whether a colonoscopy or other tests are needed

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 0–50 µg/g. Source: Mayo Clinic Laboratories, Labcorp.

Mayo Clinic Laboratories and Labcorp result categories (called normal, borderline and abnormal)

  • Normalbelow 50 µg/g
  • Borderline50 to under 120 µg/g
  • Raised120 and above µg/g

If this applies to you

Fecal calprotectin means a little more for some people. Open the one that fits you.

Celiac disease or IBD

Calprotectin is a stool marker of gut inflammation. AGA guidance uses it with symptoms to help judge whether Crohn's disease is active, and BSG notes it helps tell IBD apart from irritable bowel syndrome in younger adults with ongoing diarrhea.

Blood tests for celiac disease and IBD

What can affect your result

  • Medicines: NSAIDs and proton pump inhibitors can raise it
  • Age: infants and children under 2 have mildly higher levels, and Labcorp says results may not apply to them
  • Infections of the gut, diverticular disease and untreated celiac disease can raise it
  • Sample handling: urine mixed in, diaper samples, preserved-stool containers or old refrigerated samples can spoil the result
  • Method: the cut-offs shown here come from two labs that use different assays
  • Some medicines can raise calprotectin, including NSAID pain relievers such as ibuprofen and naproxen, and proton pump inhibitors. Do not stop any medicine unless your clinician tells you to.
  • Urine mixed into the sample, stool taken from a diaper, or stool in a preserved-stool container can spoil it (Labcorp lists these as reasons to reject a sample).
  • Samples that are refrigerated or thawed for more than 72 hours before they reach the lab are rejected (Mayo and Labcorp).
  • A very low white blood cell count (granulocytopenia) can give a falsely low result (Labcorp).
  • Labs use different methods, such as ELISA at Mayo and chemiluminescence at Labcorp, so results from different labs may not match exactly.

The result reflects inflammation in the bowel around the time of the sample.

When to talk to a clinician

Contact your clinician right away if you see blood or pus in your stool, or your stool is black and tarry. Also tell them if you have diarrhea that lasts more than a few days, belly pain that keeps coming back, or weight loss you cannot explain, whatever your calprotectin result was.

Questions you could ask

  • Why was this test ordered, and how will the result change my care?
  • Could a medicine I take, such as an NSAID or an acid reducer, explain this result?
  • Should we repeat the test in a few weeks, or look inside the bowel?
  • If my symptoms continue even with a low result, what else could we look at?

Questions people ask

Does a high calprotectin mean I have Crohn's disease or colitis?

Not by itself. It shows that the intestines are probably inflamed but not why. Infections, NSAID pain relievers and other conditions can raise it too. Your clinician may repeat the test or suggest a colonoscopy to find the cause.

My result is borderline. What happens next?

Labcorp suggests re-evaluating a borderline result (50 to 120 µg/g) in 4 to 6 weeks. Your clinician may repeat the test, check your medicines and look at your symptoms.

Can my usual medicines change the result?

Yes. NSAID pain relievers and proton pump inhibitors can raise calprotectin. Tell your clinician what you take, and do not stop any medicine on your own.

Show the science and sources

Units

  • 1 µg/g = 1 µg/g
  • 1 µg/g = 1 mg/kg

For clinicians and researchers

Calprotectin is a calcium- and zinc-binding protein (the S100A8/S100A9 complex) that makes up about 60% of the cytoplasmic protein in neutrophils. Neutrophils that migrate into the gut lumen release it, so the stool concentration tracks neutrophil influx. Mayo Clinic Laboratories uses an ELISA and Labcorp a chemiluminescence assay, and both print the same categories: under 50 µg/g normal, 50–120 µg/g borderline, above 120 µg/g abnormal. Labcorp recommends re-evaluating a borderline result in 4 to 6 weeks. The 2023 AGA guidelines for people who already have IBD suggest that, in symptomatic remission, a calprotectin below 150 µg/g plus a normal CRP (Crohn's disease), or a normal lactoferrin and/or CRP (ulcerative colitis), can rule out active inflammation. For ulcerative colitis with moderate to severe symptoms, they suggest that a calprotectin above 150 µg/g, elevated lactoferrin or elevated CRP can inform treatment decisions. These are conditional recommendations for monitoring established disease, not initial-evaluation cut-offs. Labcorp lists false negatives with granulocytopenia, and elevations with NSAIDs, proton pump inhibitors, colitis, diverticular disease, untreated celiac disease, gastrointestinal infections and colorectal cancer. MedlinePlus notes that false negatives mostly happen in children. A separate assay measures calprotectin in blood or joint fluid, and this entry covers stool only.

LOINC 38445-3 (primary). Specimen: stool.

Sources

  1. Calprotectin, Feces (test CALPR), Mayo Clinic Laboratories
  2. Calprotectin, Fecal (test 123255), Labcorp
  3. Calprotectin Stool Test, MedlinePlus Medical Tests (National Library of Medicine)
  4. AGA Clinical Practice Guideline on the Role of Biomarkers for the Management of Ulcerative Colitis, Gastroenterology (2023)
  5. AGA Clinical Practice Guideline on the Role of Biomarkers for the Management of Crohn's Disease, Gastroenterology (2023)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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