Interpretation of Results
Faecal calprotectin testing is an extremely useful tool for the clinical team to help build up a picture of what might be causing symptoms, however it is not a specific indicator of anything other than the fact that inflammation is present somewhere in the digestive system (mouth to anus!). The challenge for the clinical team it to determine where that is coming from, and if it is significant.
In the UK, many hospitals are using the York Care Pathway, which is endorsed by BSG, NICE and Crohn’s & Colitis, for interpretation of the values obtained from a faecal calprotectin test with the following criteria:
- <100µg/g = IBD is unlikely
- 100 – 250µg/g = Intermediate result – Repeat the test in 2 weeks
- >250µg/g = Likely IBD refer to secondary care
As you can see it isn’t a clear cut yes/no result – there is an intermediate range that isn’t positive, but it is higher than a negative result should be, so other factors need to be taken into consideration.
There are a variety of things that can cause the calprotectin level to be elevated other than IBD: