5 key points before ordering a fecal calprotectin test

Fecal calprotectin can be useful when there is diarrhoea, abdominal pain or persistent changes in bowel habits: it provides an indication of the likelihood of inflammation and helps determine whether further investigation is needed, but it does not replace clinical assessment or confirm a disease on its own.

In summary:

• Fecal calprotectin is a marker of intestinal inflammation measured in a stool sample.
• A low concentration may support the absence of clinically relevant intestinal inflammation, although it should be interpreted alongside symptoms and clinical assessment.
• An elevated concentration may occur in inflammatory bowel disease, but also with infections, the use of certain medicines and other conditions.
• The test can help determine which patients need further assessment, but it cannot by itself distinguish between irritable bowel syndrome and inflammatory bowel disease.

These statements are supported by NICE (HTG320) and the 2016 clinical publication; review the fecal calprotectin test with a healthcare professional.

What exactly does fecal calprotectin measure?

Fecal calprotectin measures the concentration in stool of a protein released mainly by inflammatory cells in the intestinal mucosa, so it can indicate inflammatory activity; however, on its own, it does not identify the cause or confirm a specific disease (NICE, HTG320; Fecal calprotectin in inflammatory bowel disease, 2016).

The sample analysed is a small amount of stool. When the mucosa is inflamed, immune cells can accumulate in that area, increasing the amount of calprotectin reaching the intestinal contents. As a result, the test can provide information about intestinal inflammation, but it is not a complete assessment of the entire intestine.

It is not equivalent to a diagnosis, nor does it replace the medical history, physical examination or any tests the healthcare professional considers necessary. If other aspects of digestive health need to be assessed, an intestinal microbiota analysis provides different information and does not replace an assessment of inflammation.

When can it be requested to help distinguish irritable bowel syndrome from inflammatory bowel disease?

It can be requested when digestive symptoms make it necessary to assess whether intestinal inflammation is present, particularly to help distinguish between a functional disorder and possible inflammatory bowel disease. This should always form part of a medical evaluation that considers the patient’s medical history, examination, age, background and other tests (NICE, HTG320).

The test is most informative when symptoms could correspond to either irritable bowel syndrome or inflammatory bowel disease. However, a result does not replace clinical assessment and cannot, on its own, distinguish between the two (2016 review).

Calprotectin should not delay priority medical attention if there is:

• Significant gastrointestinal bleeding.
• Persistent fever or general deterioration.
• Unexplained weight loss.
• Anaemia or an abdominal mass.

Healthcare professionals can request information about support for healthcare professionals and assess each case based on the full set of results, not calprotectin alone.

How are fecal calprotectin results interpreted?

The interpretation of fecal calprotectin depends on the cut-off values validated for the method and laboratory, as well as on the symptoms and clinical context: a low result generally makes clinically relevant intestinal inflammation less likely, whereas an elevated result does not confirm inflammatory bowel disease and requires alternative causes and next steps to be considered. (NICE; Clin Exp Gastroenterol, 2016)

Ranges should not be transferred automatically from one laboratory to another. The test may report a low, intermediate or high concentration, but the clinical meaning of each category depends on the assay used and the cut-off adopted by the laboratory.

• Low: makes clinically relevant intestinal inflammation less likely, without excluding all diseases.
• Intermediate: may require clinical correlation, a review of factors that could affect the result and, depending on the case, follow-up.
• High: may be consistent with inflammation, but can also occur in other situations; it does not establish the cause on its own.

For this reason, it is advisable to review the report with a healthcare professional and not interpret the number in isolation. If additional tests are requested, these may include other available digestive tests, depending on the clinical assessment.

What factors can raise or alter fecal calprotectin?

Fecal calprotectin may be elevated by gastrointestinal infections, non-steroidal anti-inflammatory drugs, gastrointestinal bleeding or other intestinal processes. However, this does not confirm inflammatory bowel disease. An abnormal result should therefore be interpreted alongside symptoms, medical history, medication and the laboratory method, and assessed clinically (NICE, HTG320; Clin Exp Gastroenterol, 2016).

Factors that may affect the result include:

• Gastrointestinal infections and other inflammatory processes in the intestine.
• Some medicines, including certain anti-inflammatory drugs.
• Gastrointestinal bleeding or other intestinal diseases.

Do not stop any treatment on your own: a healthcare professional should decide whether it is appropriate to adjust the treatment, repeat the sample or carry out further investigations. Repeating the test may be considered when the result does not fit the clinical picture or a likely temporary cause is present, but there is no single interval that applies to everyone. Calprotectin should also not be confused with an intestinal permeability test, such as zonulina intestinal.

What happens after receiving the result?

The result may help guide whether to monitor the situation, repeat the test or broaden the assessment with other evaluations. However, the decision lies with the healthcare professional, who must consider symptoms, physical examination, medical history and additional tests; an isolated result does not, on its own, determine the need for referral, colonoscopy or another procedure (NICE, HTG320).

Depending on the context, the healthcare professional may consider:

• Clinical observation if the result and the progression of symptoms do not suggest significant inflammation.
• Repeating the test if there are doubts about how to interpret the result or if it does not fit the symptoms.
• Ordering additional tests to investigate other causes.
• Referral to gastroenterology and consideration of endoscopy if suspicion of organic disease persists (Clin Exp Gastroenterol, 2016).

Calprotectin does not replace a medical consultation and does not, on its own, determine treatment. If the aim is also to study the composition of the intestinal microbiota, this should be understood as a separate assessment, such as Microbiota Esencial, rather than confirmation of inflammation.

Frequently asked questions

Can fecal calprotectin be used to diagnose irritable bowel syndrome?

No. Fecal calprotectin does not, on its own, confirm irritable bowel syndrome. A low result may support the absence of clinically relevant intestinal inflammation, while diagnosing this functional disorder depends on the symptoms, their progression and the clinical assessment. According to NICE, the test helps distinguish possible inflammatory processes from functional disorders, but it does not diagnose them in isolation.

Is any preparation required to collect the sample?

Collection involves obtaining a small stool sample and following the laboratory’s instructions regarding the container, storage and transport. You should not change your medication or diet on your own before the test. If there is bleeding, a recent infection or treatment with certain medicines, this should be reported to your healthcare professional so they can assess its possible influence.

Can an intestinal infection cause elevated fecal calprotectin?

Yes. A gastrointestinal infection can raise fecal calprotectin even when inflammatory bowel disease is not present. Other digestive conditions and some medicines may also have an influence. For this reason, a high result does not identify the cause on its own: it must be considered alongside the duration of the symptoms, the clinical examination and, where appropriate, other tests. This limitation is described in the review by Poullis et al. (2016).

What is the difference between fecal calprotectin and a colonoscopy?

Fecal calprotectin is a non-invasive test that estimates whether intestinal inflammation may be present based on a stool sample; a colonoscopy allows the mucosa to be viewed directly and biopsies to be taken when indicated. They are not equivalent tests, nor are they necessarily mutually exclusive. Fecal calprotectin may help guide the decision to investigate further, but the decision to perform a colonoscopy belongs to the specialist.

Can the result be interpreted without having symptoms?

Interpreting fecal calprotectin without knowing the clinical context is not recommended. The same result may have different implications depending on age, medical history, medication, a recent infection and the presence or absence of symptoms. NICE describes its usefulness mainly in people with clinical suspicion of intestinal inflammation; an isolated result does not establish a diagnosis or replace a healthcare assessment.

Read about Xenogene’s fecal calprotectin analysis and request information about the test.

Sources

• Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel (HTG320): clinical need and practice — NICE
• Fecal calprotectin in inflammatory bowel disease — Clin Exp Gastroenterol — 2016-01-01