What is Faecal Calprotein?
Faecal calprotectin is a biochemical measurement of the protein calprotectin in the stool. Elevated faecal calprotectin indicates the migration of neutrophils to the intestinal mucosa, which occurs during intestinal inflammation; including inflammation caused by inflammatory bowel disease. Under a specific clinical scenario, the test may eliminate the need for invasive colonoscopy or radio-labelled white cell scanning.
Why is it important?
The British Society of Gastrnology (BSG) sees this test as providing “differentiation between inflammatory bowel disease (IBD) and functional gut disorders, and the determination of mucosal disease activity in established cases of IBD [which] remains the cornerstones of disease diagnosis and management. Non-invasive, accurate biomarkers of gut inflammation are needed due to the variability of symptoms, the inaccuracies of currently available blood markers and the cost and invasive nature of endoscopy.”
Higher levels of faecal calprotectin are associated with active Inflammatory Bowel Disease (IBD) – such as Crohn’s Disease or Ulcerative Colitis. Testing can help clinicians distinguish between inflammatory bowel diseases and non-inflammatory bowel diseases of the lower gastrointestinal tract. 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 most commonly 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 are usually carried out to aid diagnosis.
What is the relevance to IBD?
Having a raised calprotectin level generally means you have active inflammation in your body. This is generally associated with inflammatory bowel disease. The higher the level of faecal calprotectin the more inflammation present in your intestines.However, other diseases can cause an increased excretion of faecal calprotectin such as coeliac disease, infectious colitis, necrotizing enterocolitis, intestinal cystic fibrosis and colorectal cancer.
Faecal calprotectin testing has become part of the NICE guidance for diagnosis and monitoring of IBD, as shown below in their clinical pathway:
Despite being a relatively new test, faecal calprotectin is regularly used as indicator for IBD during treatment and as diagnostic marker. Since calprotectin comprises as much as 60% of the soluble protein content of the cytosol of neutrophils, it can serve as a marker for the level of intestinal inflammation. Crohn’s disease and Ulcerative Colitis as two most common forms of IBD, are part of group of conditions that cause a pathological inflammation of the bowel wall. This inflammatory process results in an influx of neutrophils into the bowel lumen; making this test the best non invasive way to determine the level of active inflammation in the gut. This means fewer people are having unnecessary invasive testing such as endoscopies. 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.
How can it be resolved?
Typical levels of calprotectin are:
The most common cut-off value is 50 micrograms/g. Having a raised calprotectin level generally means you have active inflammation in your body. This usually means you either need to start treatment to control the inflammation or to have your dose of current treatment altered to avoid the inflammation escalating.
- 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.
- The turn around time for this test is 2 weeks.
- There are several known causes of falsely raised calprotectin levels. These are:
• NSAID treatment (excluding low dose aspirin circa 75mg)
• Systemic malignancy
• Cirrhosis of the liver
• Shingles, salmonella and c. diff infections
- Despite being a good diagnostic aid, feacal calprotectin should not be used alone to diagnose IBD.
- Faecal calprotectin has proven to be an extremely useful and cost effective marker to help differentiate between IBD and IBS. The test gained approval from NICE at the end of 2013 for screening purposes and since then the volume of calprotectin testing has increased dramatically. The calprotectin result helps doctors determine the next course of action in diagnosis and treatment of bowel conditions.
- This test can also give false positives and false negatives. Sometimes, this test is repeated weeks or months apart to get an average when considering stopping certain treatment options, such as biological drugs.
I’ve done this test on several occasions. The times before my surgery, they were used as a non-invasive way to track my levels of inflammation along side my routine blood work. They were primarily used in times when we were discussing my medication being changed.
Since surgery, we used the test to keep a track and trace on my inflammation whilst coming off medication and if this was going to prove to be fruitful. This was done slightly more regularly due to my stoma’s output. I would do two tests quite close together and then have them repeated a couple of weeks later. This was down to my output being very liquid and it would need to be more solid to get an accurate reading of the inflammation. However, in all instances, my levels all came back either as normal or just below the cut off value for IBD – at my hospital, this was 50.
Have you done the stool test? How did you find this? Is it used consistantly with your IBD? Have you had the results and have these been explained? Do you find this a good measure of your disease activity?
IBD Relief: Stool Tests for IBD
Southend University Hospital NHS Foundation Trust, Pathology Handbook: Faecal Calprotectin
The Gastrointestinal Society: Fecal Calprotectin Test
British Society of Gastroentrology: BSG Guidance on the use of Faecal Calprotectin testing in IBD
Calprotectin: Your Test for IBS/IBD
NICE Guidance & Pathways: Crohn’s Disease
National Centre for Biotechnology Information (NCBI) :The Role of Fecal Calprotectin in Investigating Inflammatory Bowel Diseases