What is a faecal calprotectin test for IBD?

What is faecal calprotectin?

Faecal calprotectin is a substance that your body releases when there is inflammation in your intestines.

Higher levels of faecal calprotectin are associated with active inflammatory bowel disease (IBD) - such as Crohn's disease or ulcerative colitis. Faecal calprotectin testing helps clinicians distinguish between inflammatory bowel diseases and non-inflammatory bowel diseases of the lower gastrointestinal tract.

How is faecal calprotectin measured?

Calprotectin is measured through a stool sample. Your doctor will give you a vial to collect the stool in. Once you have done the sample it will be sent away to a laboratory for testing.

When is faecal calprotectin measured?

Calprotectin levels are measured when IBD is suspected or to monitor someone who has IBD.

Doctors often use it to distinguish between IBS and IBD - IBS patients generally do not have raised faecal calprotectin levels as it is not an inflammatory condition.

Faecal calprotectin testing is often used when someone has been experiencing symptoms such as abdominal pain or discomfort, bloating or changes in bowel habits for six weeks or more.

Elevated levels of faecal calprotectin on their own are not enough to diagnose IBD. Other tests, such as blood tests, scans and/or endoscopies, may also be carried out to aid diagnosis.

Some hospitals carry out routine faecal calprotectin tests on their existing IBD patients as a way of monitoring how they are doing while other hospitals just do it if the patient is in a bad flare or if they are undergoing a new treatment/medication.

The introduction of faecal calprotectin testing means that many fewer people are having unnecessary invasive tests such as endoscopies.

What does having a raised faecal calprotectin level mean?

Having a raised calprotectin level generally means you have active inflammation in your body. This is generally associated with inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis. The higher the level of faecal calprotectin the more inflammation present in your intestines.

If you have IBD but your calprotectin levels come back within the ‘normal’ range then your doctor would generally consider you to be in clinical remission.

What are considered normal levels of faecal calprotectin?

Most people have some level of calprotectin in their body but when these levels go above what is considered to be ‘normal’ IBD may be suspected. Some people with IBS or other conditions may have levels of calprotectin that are slightly raised above the ‘normal’ level.

The results of a calprotectin test are generally given as a single number. This number is then compared against the cut-off value for the test. If the number is below the cut-off value it is considered a negative, or normal, test. If it is above the cut-off value it is considered a positive, or abnormal, test. In some cases an indeterminate result may be given if the result number is near to the cut-off value and a positive or negative test cannot be confirmed. In these cases the faecal calprotectin test may be repeated at a later date or other diagnostic tests may be carried out.

There are many different manufacturers of calprotectin tests and the cut-off value differs from test to test. The most common cut-off value recommended by the test manufacturers is 50 micrograms/g.

Some people with IBD report having faecal calprotectin levels several hundred, or even thousand, above the cut-off level.

Can you have ‘normal’ faecal calprotectin levels but still have IBD?

Yes. Increased levels of faecal calprotectin are associated with lower gastrointestinal (GI) inflammation (small intestine and large intestine). If your levels come back normal you could still have Crohn’s disease in the upper part of your GI tract or you could currently be in clinical remission meaning there is currently no active inflammation in your intestines.

IBD is a chronic, life-long condition which cannot currently be cured. If you have previously been diagnosed with IBD but your faecal calprotectin levels are below normal then it is likely you are in remission and have not been cured.

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