Faecal Calprotectin Levels in Cancer: Interpreting Results

Faecal calprotectin is a stool marker of inflammation in the bowel. Although levels can be raised in some colorectal cancers, an elevated result is much more commonly caused by non-cancerous inflammation, infection, medicines, or other digestive conditions.

Overview: what faecal calprotectin can and cannot show

Faecal calprotectin levels in cancer can be elevated when a tumour causes inflammation or bleeding within the bowel, particularly in colorectal cancer. However, calprotectin is not a cancer test: it measures a protein released by inflammatory cells, so it signals intestinal inflammation rather than identifying its cause.

For many adults, a result below 50 micrograms per gram (µg/g) of stool is considered within the usual reference range. Results above this range may be seen with many conditions, most of which are not cancer. A clinician considers the number together with a person’s symptoms, age, medical history, medication use, and other findings before deciding whether further tests are needed.

The test is especially useful for helping distinguish inflammatory bowel conditions from functional symptoms such as irritable bowel syndrome (IBS). It should not replace recommended bowel Bladder Cancer Screening: How It Works, Results and What to Expect" class="ahp-ilk">cancer screening or prompt reassurance when concerning symptoms are present.

Reference ranges: the number comes first, then the context

Reference intervals differ slightly between laboratories and test methods, so the range printed on the individual report should always be used. In many adult services, a result below 50 µg/g is regarded as normal. A result from about 50 to 120 or 150 µg/g may be described as borderline or indeterminate, while values above approximately 150 to 250 µg/g more strongly support active intestinal inflammation.

These cutoffs are practical guides, not universal diagnostic thresholds. A mildly raised result may be repeated after a clinician has reviewed possible temporary causes. A higher or rising result, particularly with persistent symptoms, often warrants more timely evaluation. Very high values can occur in severe inflammation or infection, but they are not specific to any one disease.

Age matters. Healthy infants and young children can have higher calprotectin levels than adults, and laboratories may apply different pediatric ranges. Older adults may also need more careful assessment of an elevated result because conditions such as diverticular disease, polyps, medication effects, and bowel cancer become more common with age. There is no established sex-specific normal range that is routinely used in practice.

• Below 50 µg/g: usually reassuring in adults, when symptoms and clinical risk are low.
• About 50–150 µg/g: may be transient or mild inflammation; repeat testing or review may be appropriate.
• Above 150–250 µg/g: suggests meaningful intestinal inflammation and commonly leads to further evaluation.
• Markedly elevated: needs clinical assessment, but does not indicate cancer by itself.

What level of fecal calprotectin indicates cancer?

There is no faecal calprotectin level that indicates cancer on its own. Some people with colorectal cancer have elevated results, including levels above 250 µg/g, but similarly high results can occur with inflammatory bowel disease, bacterial gastroenteritis, diverticulitis, and other non-cancerous causes. Conversely, a normal calprotectin result does not completely exclude cancer.

Calprotectin is therefore not used as a stand-alone screening or diagnostic test for colorectal cancer. When cancer is a concern, clinicians may use symptom assessment, blood tests for anemia, stool-based screening tests that detect blood or DNA changes, colonoscopy, and imaging as appropriate. Colonoscopy allows direct inspection of the bowel and removal or biopsy of suspicious tissue.

The significance of a result depends on the whole clinical picture. An elevated level in a younger person with a recent diarrheal illness may be managed very differently from the same result in an older adult with iron-deficiency anemia, rectal bleeding, or unintended weight loss.

What level of calprotectin is concerning?

A calprotectin level is concerning when it is persistently above the laboratory range, clearly elevated, increasing on repeat testing, or accompanied by symptoms that suggest bowel inflammation or another significant digestive condition. For adults, results above roughly 150 to 250 µg/g are more likely to represent active intestinal inflammation than borderline results, but the exact action threshold differs by local laboratory guidance and individual risk factors.

A borderline result may not require urgent invasive testing. A clinician may ask about a recent stomach infection, use of anti-inflammatory pain medicines, or a flare of known bowel disease, then recommend repeating the test after an appropriate interval. Repeat testing can help distinguish a short-lived rise from continuing inflammation.

Symptoms can be more important than the number alone. Ongoing diarrhea, abdominal pain, blood in the stool, nighttime bowel symptoms, fever, weight loss, or fatigue related to anemia should be assessed even if the calprotectin result is only mildly raised or normal. People with established inflammatory bowel disease may also have calprotectin monitored as one part of assessing disease activity.

What cancers have high calprotectin?

Colorectal cancer is the cancer most often considered when a high faecal calprotectin result is discussed. A cancer in the colon or rectum can disrupt the bowel lining and attract inflammatory cells, increasing calprotectin in stool. Colorectal polyps, especially if they are large or inflamed, may also be associated with a raised result but are not cancer in themselves.

Other cancers involving the digestive tract may occasionally be associated with elevated calprotectin if they cause bowel inflammation, obstruction, ulceration, or bleeding. However, the test is not validated to diagnose or reliably identify stomach, pancreatic, small-bowel, or cancers outside the digestive tract. It cannot tell where inflammation is located or whether it is caused by a tumour.

Because the test is nonspecific, a raised result should not be interpreted as evidence that a person has cancer. If symptoms, family history, age, or screening findings suggest a higher risk, a doctor may recommend colonoscopy or another appropriate investigation to identify the underlying cause.

What can falsely elevate calprotectin?

The term “falsely elevated” can be misleading because the number often reflects genuine bowel inflammation, even when cancer or inflammatory bowel disease is not present. Common temporary causes include viral or bacterial gastroenteritis, foodborne illness, and recent intestinal infection. Testing during or soon after an episode of diarrhea can therefore produce a higher result.

Medicines may also contribute. Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, can irritate the gastrointestinal lining and raise calprotectin. Acid-suppressing proton pump inhibitor medicines have also been associated with modest elevations in some people. A person should not stop prescribed medicine without medical advice, but should tell the clinician and laboratory team what they are taking.

Other possible causes include diverticular disease, colorectal polyps, celiac disease, gastrointestinal bleeding, microscopic colitis, and inflammatory bowel disease. Stool sample contamination, collection errors, or delayed handling can sometimes affect a test result, although laboratories use validated procedures to reduce this risk. A repeat sample may be helpful when the result does not fit the symptoms or medical history.

Intense endurance exercise may temporarily affect gastrointestinal inflammation in some individuals. Clinicians may also interpret results cautiously in very young children, older adults, and people with known bowel conditions because standard adult thresholds may not fully apply.

How doctors investigate an elevated result

After reviewing the result, a doctor will ask about the duration and pattern of symptoms, recent travel or infection, medicines, family history, and previous bowel investigations. They may perform an abdominal examination and request blood tests to look for inflammation, anemia, infection, or nutritional deficiencies. Stool tests for infection may be useful when diarrhea is present.

If a result is mildly elevated without alarm symptoms, repeating calprotectin after possible temporary triggers have resolved may be reasonable. If levels remain high, symptoms are persistent, or there are risk factors for serious bowel disease, referral to a gastroenterologist may be advised. Further assessment may include colonoscopy, bowel imaging, or other targeted tests.

For people undergoing investigation for colorectal symptoms, a high calprotectin result may support the need to look for inflammation, but it does not decide the diagnosis. Findings from a gastroenterology assessment and any procedures are interpreted together to guide care.

When to seek medical care

Anyone with a high or borderline faecal calprotectin result should discuss the finding with the clinician who ordered the test, particularly if it remains raised on repeat testing. Prompt medical review is important for rectal bleeding, black or dark stools, persistent changes in bowel habit, ongoing diarrhea, severe or worsening abdominal pain, unexplained weight loss, fever, or marked tiredness.

People should also seek assessment if they have symptoms of anemia, such as unusual breathlessness, dizziness, or persistent fatigue, or if they have a personal or strong family history of colorectal cancer, bowel polyps, or inflammatory bowel disease. These symptoms have many possible causes, but they should not be attributed to a calprotectin result alone.

Acıbadem Health Point’s multidisciplinary specialists and JCI-accredited hospitals evaluate digestive symptoms and abnormal stool-test results for international patients, using investigations selected according to each person’s clinical needs.

Frequently asked questions