What is a faecal calprotectin test? Everything you need to know.
What is a faecal calprotectin test?
Put simply - faecal is poo, and calprotectin is a protein that is found in our poo when there is inflammation in our intestines.
When there is inflammation in our intestine, immune cells move to the site of the inflammation and release calprotectin which then shows up in our poo. Generally, the more inflammation there is in our intestine, the higher the calprotectin reading will be.
When is calprotectin testing used?
Faecal calprotectin can be useful in helping to work out whether someone might have an inflammatory bowel condition (like Crohn’s Disease or Ulcerative Colitis, a bacterial infection, a parasitic infection or colorectal cancer) or a non-inflammatory bowel condition (like IBS or a viral infection). The symptoms of these two can be similar but they are two very different conditions.
Calprotectin is raised in active IBD but not in IBS. This can help your GP to guide you to the right care and to prevent unnecessary investigations like endoscopies (a camera put inside the digestive system to see what’s going on).
Calprotectin testing in IBD
Faecal calprotectin can also be a really useful tool as an ongoing monitor of treatment and disease progress in Crohns Disease and Ulcerative Colitis. It helps to give us an insight as to how things might be healing and into potential relapse risk. Research has shown that raised calprotectin levels can help predict whether someone with Crohns or Colitis might have a flare in the near future.
The difficulty is, we don’t have a distinct cut off value between high and low calprotectin levels when looking at relapse/flare risk. Some suggest a cut-off point of 250μg/mg, but others suggest lower cut off points.
What does raised calprotectin mean?
As a screening tool - If the test result shows raised faecal calprotectin, this means there is inflammation somewhere in the intestines. This cannot tell us where that inflammation is or what is causing it though. That’s where endoscopies, colonoscopies and sigmoidoscopies can be useful to determine where the inflammation is exactly and what it is.
As an IBD monitoring tool - Raised faecal calprotectin in IBD can indicate there is active disease and how active it is. It can also suggest potential relapse risk in those with no symptoms. Some research in patients with IBD in remission and no symptoms showed that 90% of patients with a high faecal Calprotectin level relapsed within a year, whilst only 10% of those with a low faecal Calprotectin level relapsed within the same period.
What do calprotectin results mean?
I have put together the table below to show what the different values mean and what might happen in that instance if you do not have a diagnosis and you are having tests done with your GP (this is based on NHS NICE guidelines):
What do calprotectin results mean in IBD?
There are currently no universally agreed cut off figures for monitoring IBD with faecal calprotectin (FC). However, the literature and general consensus suggest the following, although different IBD teams may have different opinions on values:
<50ug/g minimal/no inflammation
<250ug/g - keep monitoring
>250ug/g - above target range - review is needed, possibly increase, addition or change in meds, possibly scope needed to most accurately assess disease activity.
If you have Crohns or Colitis and are having a flare or relapse, calprotectin levels can reach the thousands and you may need treatment like steroids to help to bring the inflammation under control.
Monitoring the trends in your calprotectin over time is a really useful tool for you and your IBD team to see the activity of your IBD and response to treatment.
Patient tip - if your FC is between 100-250ug/g and you don't have symptoms don't panic, ask your team to repeat in 2 months to monitor progress.
If you are struggling with your diet with your Crohns Disease or Ulcerative Colitis we can help you.
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References:
NHS (2018) Faecal Calprotectin in Primary Care as a Decision Diagnostic for Inflammatory Bowel Disease and Irritable Bowel Syndrome. [online] Available from: https://www.nice.org.uk/guidance/dg11/resources/endorsed-resource-consensus-paper-pdf-4595859614 (Accessed 9th February 2023)
Freeman K, Ryan R, Parsons N, Taylor-Phillips S, Willis BH, Clarke A. Faecal calprotectin testing in UK general practice: a retrospective cohort study using The Health Improvement Network database. Br J Gen Pract. 2021 Oct 28;71(712):e854-e861. doi: 10.3399/BJGP.2021.0125. PMID: 34607795; PMCID: PMC8510694.