What is the Fecal Calprotectin Test?

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This article was made possible due to an unrestricted educational grant from Diasorin, the Diagnostic Specialist. 

Fecal Calprotectin Test: A biomarker of intestinal inflammation

Your stool has a story to tell – good or bad – about what’s happening in your body.

When a person has inflammation of the bowel, neutrophils and other inflammatory cells release a cytosolic protein called calprotectin. The fecal calprotectin test is a non-invasive stool test that involves the collection and analysis of your stool to measure the amount of the calprotectin in it.

The fecal calprotectin test is often used to differentiate between irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).

IBS and IBD are two conditions with common symptoms such as diarrhea, abdominal bloating, and cramping, but are in fact quite different and have very different treatment options.

  • IBS is a disorder affecting the intestine. IBS involves problems with motility (movement of digested food through the intestines) and sensitivity (how the brain interprets signals from the intestinal nerves), leading to abdominal pain, changes in bowel patterns and other symptoms. IBS is a functional gut disorder. Functional means that the affected area (intestines) are impaired and not working the way they should, however there are no visible abnormalities that can be observed through testing. IBS symptoms are commonly controlled through diet, and lifestyle changes and in more severe cases, medication.
  • IBD is at least two separate disorders that cause inflammation (redness and swelling) and ulceration (sores) of the small and large intestines. These two disorders are called ulcerative colitis and Crohn’s disease and symptoms can range from mild to debilitating, and even life-threatening. Since the disease is not curable, long-term treatment is often required.

Not only is the fecal calprotectin used to distinguish between IBD and non-inflammatory disorders such as IBS, but if you have already been diagnosed with IBD, it can be used to monitor your IBD. This includes:

  • Assessing response to treatment,
  • assessing mucosal healing,
  • and even predicting flares!

How does the fecal calprotectin accurately diagnose or monitor IBD?

After your stool is analyzed, your doctor will look at your test results and determine whether your levels of calprotectin are normal (low), borderline(moderate), or abnormal (high). A high level can indicate IBD, whereas a lower level can indicate a functional bowel disease such as IBS.

Let’s take a closer look at the levels:

  • Low or normal levels (< or =50.0 mcg/g) may indicate that that there is no inflammation, and you are in remission OR if you are having symptoms, that these symptoms are not caused by inflammation (i.e caused by irritable bowel syndrome or some other cause). Knowing this will help to exclude IBD, and avoid unnecessary referrals and colonoscopies.
  • Moderate or borderline levels (50.1-120.0 mcg/g) can indicate that some inflammation is present and could be due to treated inflammatory bowel disease (IBD) or associated with the usage of nonsteroidal anti-inflammatory drugs (NSAID), aspirin, or proton-pump inhibitors. For patients with moderate levels and clinical symptoms suggestive of IBD, retesting in 4 to 6 weeks may be needed.
  • High or abnormal levels (> or =120.1 mcg/g) can suggest that you have active inflammation. High levels don’t always explain the reason for inflammation so your doctor may order additional tests. An endoscopy (colonoscopy or sigmoidoscopy) may be indicated as a follow-up test to help determine the cause of inflammation, signs, and symptoms.

What are the other testing options?

Diagnosing IBD is normally confirmed by performing an endoscopy (colonoscopy or sigmoidoscopy) to examine the intestines and by obtaining a small tissue sample (biopsy) to evaluate for inflammation and changes in tissue structures. This kind of testing can be invasive, and is less likely to be necessary if inflammation is not present – so the fecal calprotectin test is a great, less-invasive option to confirm. (1)

There are blood tests used to detect inflammation, but they do not provide the same information about inflammation as the fecal calprotectin test, or the location of the inflammation. It’s important to note that calprotectin is a reflection of intestinal inflammation and is not affected by lifestyle changes. If its due to an infection, then it will most likely return to normal when the infection goes away. If it is fact due to IBD, then it will rise and fall when you are in remission or in a flare.

You can develop IBS or IBD at any age. If you are experiencing persistent symptoms such as bloody or watery diarrhea, abdominal cramps, with or without fever, or are looking to proactively monitor your condition, CDHF recommends talking to your doctor to decide if the fecal calprotectin test is an option for you.

Watch our CDHF Talk with Dr. Karen Kroeker from the University of Alberta who explains the important role stool tests play in diagnosis and treatment of digestive disorders.


References:

(1) Journal of Clinical Gastroenterology: March 2021 – Volume 55 – Issue 3 – p 239-243 doi: 10.1097/MCG.0000000000001359

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390326/

https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/63016

https://www.lifelabs.com/test/fecal-calprotectin-testing/?gclid=Cj0KCQiAys2MBhDOARIsAFf1D1fRD7BVl80FFYwbmyAYOFJEmoGh0XqK2YbTWDZ5n3mi3h63iUvoCigaAtPBEALw_wcB

https://pubmed.ncbi.nlm.nih.gov/21122498/#:~:text=Conclusions%3A%20Fecal%20calprotectin%20may%20be,pattern%2C%20compared%20with%20ileal%20CD.