Short answer · Medically reviewed summary · Last updated: 2026-04-07
Factor V Leiden is primarily diagnosed through specialized blood tests, specifically a clotting screen or a DNA-based genetic test that identifies the specific mutation in the F5 gene. The Diagnostic Process In many cases, the diagnostic journey for Factor V Leiden begins only after an individual experiences a venous thromboembolism (VTE), such as deep vein thrombosis (DVT) or a pulmonary embolism (PE). Because Factor V Leiden often presents no outward symptoms until a clot forms, patients frequently feel frustrated by the lack of warning signs.
6 people with Factor V Leiden have shared their first-person experience on this question at DiseaseMaps.
How is Factor V Leiden diagnosed?
How Factor V Leiden is diagnosed: tests, specialists and the diagnostic journey, told by patients and reviewed against medical sources.
Factor V Leiden is primarily diagnosed through specialized blood tests, specifically a clotting screen or a DNA-based genetic test that identifies the specific mutation in the F5 gene.
The Diagnostic Process
In many cases, the diagnostic journey for Factor V Leiden begins only after an individual experiences a venous thromboembolism (VTE), such as deep vein thrombosis (DVT) or a pulmonary embolism (PE). Because Factor V Leiden often presents no outward symptoms until a clot forms, patients frequently feel frustrated by the lack of warning signs. If a clinician suspects a hypercoagulable state—often due to a family history of clots or a clotting event at a young age—they will order blood work to assess how quickly the blood clots in a laboratory setting.
Key Tests and Clinical Specialists
The gold standard for diagnosis is a genetic test performed on a blood sample to detect the presence of the Factor V Leiden mutation. A hematologist is the specialist best equipped to manage this diagnosis. They help distinguish Factor V Leiden from other conditions that cause blood to clot too easily, such as Protein C or S deficiency, Antithrombin III deficiency, or Prothrombin G20210A mutation. Imaging tests like ultrasounds for DVT or CT scans for PE are used to treat the immediate clot, but they do not diagnose the underlying genetic condition itself.
Overcoming the Diagnostic Odyssey
The "diagnostic odyssey" is a well-known struggle for those with rare conditions. Because Factor V Leiden is often asymptomatic, many patients go years without knowing they carry the gene. If your primary care provider is unfamiliar with thrombophilia testing, do not hesitate to request a referral to a hematologist. Seeking a specialist is crucial, as they can provide tailored advice on risk factors—such as pregnancy, surgery, or long-distance travel—that may trigger a clotting event in someone with Factor V Leiden.
Medical Disclaimer: This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Factor V Leiden Thrombophilia
- Orphanet: Factor V Leiden mutation
- National Heart, Lung, and Blood Institute (NHLBI): Venous Thromboembolism
Posted May 4, 2017 by Dawn B 1000
Posted May 4, 2017 by Jennifer 1000
Posted May 11, 2017 by Stacy 2650
Posted May 16, 2017 by Rachael 1000
Two types of tests can be done:
1) Activated protein C resistance test. Your blood sample may be tested to determine whether your blood is resistant to activated protein C, one of the anti-clotting proteins that help control factor V. This is known as an activated protein C (APC) resistance assay. If your blood is resistant to activated protein C, you likely have a mutation in the factor V gene.
2) Genetic test. A genetic test is done to determine whether you have a factor V gene mutation. It may also be used to confirm the results of the APC resistance test or to determine whether you've inherited one or two copies of the gene mutation.
Posted Dec 28, 2017 by Barbara 4050
Posted May 22, 2018 by Rose 500
