This is a guideline from the British Society of Haematology on when to test for thrombophilia. It was published in May 2022. A lot of this is aimed at secondary care, but there are some elements that are useful for us. It is the kind of thing that comes up every now and again and I often struggle to know whether I should be testing someone or no – and what I should actually be testing for. This guideline helps a lot. I shall try to outline the things I think are useful for us. There is a lot more detail in the guideline, so it is a good place to look if you have a specific clinical scenario.
Why is this thrombophilia guidance so important?
- Antithrombin (AT) deficiency is associated with a 15 times increased chance of a first VTE. It can be inherited.
- Protein C (PC) and Protein S (PS) deficiencies are associated with a 5 to 7 times increased risk of first VTE. These can be inherited.
- Factor V Leiden (FVL) is a mutation in the Factor V gene that increases the chance of coagulation. There are other mutations in the same gene that can cause an increased change of coagulation too. FVL has a 5 times increased risk of first VTE. This can be inherited.
- Antiphospholipid (APL) syndrome is not inherited. It is an acquired disorder. For more information on APL syndrome, there is a good article on patient.co.uk.
It is important to be aware that in people with a thrombophilia, that transient provoking factors account for 50% of VTE. The inherited risk and the provoking factors interact in bringing around the chance of VTE.
When GPs talk about thrombophilia testing, what do we mean?
Normally testing is done on protein levels, or looking for antibodies. This is because there are multiple genetic variants for these thrombophilia.
