Most blood clots have an obvious trigger — a long flight, surgery, immobility or pregnancy. But when a clot happens without a clear reason, or clots keep recurring, doctors sometimes look for an underlying tendency for the blood to clot too readily. This tendency is called thrombophilia, and testing for it is a careful, considered process.
What thrombophilia means
Thrombophilia describes a state in which the blood's clotting balance is tipped towards forming clots more easily than it should. It can be inherited, present from birth in the genes, or acquired later in life — for example through an autoimmune condition. Having thrombophilia does not guarantee a clot will happen; it simply raises the background risk, particularly when combined with other triggers.
What the testing involves
Thrombophilia testing is a bundle of related blood tests rather than a single result. Depending on the situation it can include:
- Fibrinogen — the protein central to forming a clot.
- PT and APTT — baseline clotting times.
- D-dimer — a marker of ongoing clot formation and breakdown.
- Lupus anticoagulant — one of the antibodies linked to an acquired clotting tendency.
Specialists may add further tests for specific inherited factors, and often repeat abnormal results after a gap, since a single reading can be misleading.
When testing is considered
Because a positive result rarely changes everyday management on its own, testing is reserved for circumstances where it may genuinely alter decisions. These include:
- An unexplained clot, especially at a young age or in an unusual site.
- Recurrent clots despite no obvious trigger.
- Recurrent miscarriage or certain pregnancy complications.
- A strong family history of clots at a young age.
Assess clotting risk
Our clotting risk bundle assesses thrombophilia with markers including fibrinogen, PT, APTT, D-dimer and lupus anticoagulant — best used in the situations above and interpreted with a specialist.
Assess clotting riskWhy timing matters
Several factors can distort thrombophilia results. Levels of some clotting proteins fall temporarily just after a clot, pregnancy alters the picture, and blood-thinning medication changes several of the tests. For this reason specialists often advise testing when you are well and, where relevant, off anticoagulation — which is one more reason the results need expert interpretation rather than being read at face value.
When to get checked
If you have had an unexplained or recurrent clot, or recurrent pregnancy loss, it is worth discussing thrombophilia testing with a doctor who can judge whether it is appropriate and time it correctly. A clot itself — sudden breathlessness, chest pain, or a painful swollen leg — is always a medical emergency; call 999 rather than arranging a test.
Assess clotting risk
Book online with OneMedicine — CQC-registered clinic in Birmingham, or a home visit / local clinic nationwide. Doctor-reviewed results, most within 24 hours.
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Specialist interest: Cardiovascular Medicine · OneMedicine, CQC-registered clinic