Fecal Calprotectin Test

Calprotectin Test

A calprotectin test is a procedure used to detect the presence of calprotectin in the stool. The procedure is also called stool calprotectin or fecal calprotectin test.

What is calprotectin? It is a type of protein released by neutrophil; a particular type of white blood cell. If there is an inflammation in the gastrointestinal tract, neutrophils move to the inflammation site and release calprotectin.

It will result in an increased level of calprotectin in the stool. The calprotectin test is one of the parameters used to detect gastrointestinal problems such as inflammation of the intestines. ^{(1, 2, and 3)}

Picture 1: A fecal calprotectin test checks for the presence of inflammation in the intestines.

Image Source: lalpathlabs.com

Picture 2: Calprotectin is a type of protein released by white blood cells.

Image Source: verywellhealth.com

Picture 3: Inflammatory bowel disease can be suspected in patients with increased calprotectin test.

Image Source: lalpathlabs.com

How is a calprotectin test performed?

A fresh stool sample is needed, put in a clean container and send to the laboratory as soon as possible.

Make sure that the stool sample is not contaminated with anything; be it water or urine. No special preparation is needed for such a procedure. ^{(2, 3)}

Why is it important to measure the level of calprotectin in the stool?

By measuring the level of calprotectin in the stool, it will be easy to detect the presence of inflammation in the intestines. Any inflammation in the intestine can be associated with bacteria and inflammatory bowel disease.

The procedure is not diagnostic in nature but can be used to differentiate between inflammatory and non-inflammatory bowel disorders. Most importantly, it helps in detecting the severity of inflammatory bowel disease. ^{(3, 4, and 5)}

When is a calprotectin test ordered?

Your doctor will order for a calprotectin test if you have the following:

1. Persistent watery stool
2. Bloody diarrhea
3. If the doctor suspects inflammation
4. To find out if endoscopy is needed in patients suspected with irritable bowel disease
5. If the person who has irritable bowel disease has symptoms indicating a flare-up to check for disease activity and to gauge the severity of the disease. ^{(4, 5, and 6)}

The test is ordered to rule out conditions with similar signs and symptoms. Additional testing is necessary to accurately diagnose the condition of the patient such as:

• Stool culture
• Ova and parasite test
• Stool white blood cell test
• Fecal Occult Blood Test
• C-reactive protein
• Erythrocyte sedimentation rate ⁽⁷⁾

What does the test result mean?

The level of calprotectin is measured to find out the health condition of the patient. ⁽⁶⁾

Why is my calprotectin high?

If a patient’s stool has an elevated calprotectin level, it means that the patient is suffering from inflammation in the intestines. However, it does not point out the exact cause or location of the inflammation.

The higher the calprotectin level, the more severe the inflammation will be. An increase in calprotectin is seen in patients with irritable bowel disease, bacterial infection, parasitic infection, and colorectal cancer.

A positive calprotectin test result is more than 200 µg/g. the patient needs to be referred to a gastroenterologist for further testing, treatment, and management. ^{(2, 7, and 8)}

What is the reason for a low calprotectin level?

If the result of calprotectin test is low, it means that the patient’s signs and symptoms are caused by a non-inflammatory bowel disorder such as viral infections affecting the digestive tract. It could also be caused by irritable bowel syndrome, which causes stomach pain characterized by cramps and spasms with a bout of diarrhea or constipation.

A calprotectin test is negative if the values are less than 50 µg/g.  Just because the result is low does not necessarily mean that there is nothing wrong in the body. It only means that the symptoms the patient currently experience is not related to inflammatory bowel disease. Other possible causes can be:

• Irritable bowel syndrome
• Food allergy
• Celiac disease
• Intolerance ⁽⁹⁾

What is the reason for a moderate calprotectin level?

If the level of calprotectin is moderate, it means that there might be some inflammation and that a patient’s condition is getting worse. If the test is performed again and the result showed moderately elevated calprotectin, it means that the patient needs further investigation such as an endoscopy.

If the calprotectin level is between 50 – 200 µg/g, it means that the level is moderate or mid-range. It is more than normal but still lower than the positive result. It can be associated with a lot of factors such as:

• Mild diverticulitis
• Bacterial infection
• Intake of non-steroidal anti-inflammatory drugs like ibuprofen or aspirin
• Excessive alcohol intake
• Side effects of drugs like proton pump inhibitors
• Anything that can irritate the lining of the intestines.

If the result of calprotectin test is moderate, it is best to repeat the procedure after two to three weeks. If the level continues to rise, then further investigation is needed. ^{(2, 8, 9, and 10)}

Picture 4: Irritable bowel syndrome can be one of the culprit for patients with gastrointestinal symptoms but have low calprotectin.

Image Source: prod-carehubs.net

What to keep in mind?

• An inflammation in the intestine causes an elevation in the level of calprotectin in the stool.
• The level of calprotectin may increase with intestinal tissue damage and bleeding which is usually linked with the use of non-steroidal anti-inflammatory drugs like ibuprofen.
• Calprotectin test is related to lactoferrin; a substance released by white blood cells in the stool. It is also linked with inflammation of the intestines. ^{(3, 4, and 5)}

Facts about fecal calprotectin test

• A calprotectin is a protein found in white blood cells.
• The level of calprotectin is high in people with inflammatory bowel disease.
• A stool sample is needed to check for the level of calprotectin.
• The normal level of calprotectin varies from one person to another.
• It could be possible that the level of calprotectin is high even if the patient does not have symptoms of inflammatory bowel disease. ^{(1, 7, and 9)}

References

1. https://labtestsonline.org/tests/calprotectin
2. https://www.badgut.org/information-centre/a-z-digestive-topics/fecal-calprotectin-test/
3. https://www.calprotectin.co.uk/about-calprotectin/information-for-patients/
4. https://www.clinicallabs.com.au/functional-pathology/practitioners/functional-tests-arterial/calprotectin-test/
5. https://www.nice.org.uk/guidance/dg11
6. https://dtb.bmj.com/content/52/9/102
7. https://www.ibdrelief.com/learn/what-is-faecal-calprotectin-test-for-ibd
8. https://discovertherapies.com/articles/42-fecal-calprotectin-test-for-crohn-s-and-colitis
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390326/
10. https://www.verywellhealth.com/how-the-fecal-calprotectin-test-is-used-in-ibd-4140079