Home
/
Markers
/
Coagulation
/
Factor V Leiden

Factor V Leiden Test

Factor V Leiden is the most common inherited thrombophilia. This one-time genetic test provides lifelong information about your clotting risk.

Doctor's Assessment Included

Reference Ranges

Expected result Negative

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

Factor V Leiden: what this test measures

This test identifies the Factor V Leiden mutation (R506Q) through DNA analysis. Results indicate whether you are negative, heterozygous (one copy), or homozygous (two copies) for the mutation.

Factor V Leiden: why this value matters

Factor V Leiden is present in approximately 5% of Caucasian populations. Heterozygous carriers have a 3-8x increased thrombosis risk; homozygous carriers have up to 80x increased risk. Knowing your status informs decisions about contraception, pregnancy, surgery, and travel.

Factor V Leiden: when is testing worthwhile?

Testing is recommended for unexplained venous thrombosis (especially under age 50), family history of Factor V Leiden or thrombosis, recurrent pregnancy loss, or before starting oestrogen-containing contraception with a relevant family history.

Factor V Leiden: symptoms of a high or low value

Low Levels

A negative result means you do not carry the Factor V Leiden mutation. Your thrombosis risk from this factor is at the population baseline level.

High Levels

Carrying the mutation does not cause symptoms directly. It increases the statistical risk of developing venous thrombosis, particularly when combined with other risk factors such as surgery, immobility, pregnancy, or oestrogen use.

Factor V Leiden: lifestyle and this value

If you carry Factor V Leiden, reduce modifiable thrombosis risk factors: maintain a healthy weight, stay active, avoid smoking, stay hydrated during travel, and discuss all hormonal medications with your healthcare provider.

Factor V Leiden: frequently asked questions

Will I definitely get a blood clot if I carry Factor V Leiden?

No. Most heterozygous carriers never experience a clot. The mutation increases risk but does not guarantee a thrombotic event.

Should my family be tested?

If you are a carrier, first-degree relatives may benefit from testing, especially before high-risk situations like surgery, pregnancy, or starting oestrogen therapy.

Can I use hormonal contraception with Factor V Leiden?

Oestrogen-containing contraception significantly increases thrombosis risk in carriers. Progestogen-only methods are generally considered safer. Discuss options with your healthcare provider.