Factor V Leiden Mutation Analysis (F5 R506Q) Biomarker Testing
It checks whether you carry the Factor V Leiden gene variant linked to higher clot risk, with easy ordering and clear results through Vitals Vault and Quest.
From $186.99 · Quest Diagnostics
- No subscription
- HSA/FSA eligible
- Most results in 3–5 business days
Factor V Leiden Mutation Analysis is a genetic lab test that checks whether you carry a specific change in the F5 gene (often reported as Factor V Leiden or R506Q). This variant can make your blood more likely to form clots in veins, especially when other risk factors are present.
This test does not tell you whether you have a clot right now. Instead, it helps explain why a clot may have happened, whether your risk is higher than average, and how you and your clinician might approach prevention in higher-risk situations like surgery, long travel, pregnancy, or estrogen-containing medications.
Because it is a DNA-based result, it usually does not change over time. The main “interpretation work” is understanding what your specific result means for your life and what other tests or history details should be considered alongside it.
Do I need a Factor V Leiden Mutation Analysis test?
You may want this test if you have had a deep vein thrombosis (DVT) or pulmonary embolism (PE), especially if it happened at a younger age, occurred without a clear trigger, or happened more than once. In those situations, knowing whether you carry Factor V Leiden can help your clinician decide how aggressively to look for other clotting risks and how to plan prevention around future high-risk events.
This test is also commonly considered if you have a strong family history of venous blood clots, or if a first-degree relative (parent, sibling, child) has a known Factor V Leiden result. It can be particularly useful before starting estrogen-containing birth control or hormone therapy, or when planning pregnancy, because estrogen and pregnancy both increase clot risk on their own.
You usually do not need Factor V Leiden testing for arterial events like heart attack or most strokes, because the strongest association is with venous clots. If you are being evaluated for pregnancy loss or complications, your clinician may or may not include this test depending on your history and current guidelines.
Testing works best when it supports clinician-directed care rather than self-diagnosis. Your personal clot history, family history, and current medications often matter as much as the gene result.
This is a laboratory genetic test typically performed in a CLIA-certified lab; results should be interpreted with your clinician and do not diagnose an active clot.
Order labs to measure Factor V Leiden Gene Test
from $186.99 at Quest Diagnostics.
Get this test with Vitals Vault
Vitals Vault makes it simple to order Factor V Leiden Mutation Analysis when you and your clinician want a clear yes/no genetic answer rather than a symptom-based guess. You can order your lab test and complete the blood draw through a national lab network, then review the result in one place.
If your report shows you carry the variant, the next step is usually planning: when you might need extra clot prevention, which medications or situations raise your risk, and whether additional thrombophilia testing is appropriate. PocketMD can help you turn the lab language into practical questions to bring to your clinician.
If your result is negative but your history suggests higher risk, PocketMD can also help you understand what else may be worth checking (for example, prothrombin gene mutation, antiphospholipid antibodies, or protein C/S and antithrombin activity) and when retesting is or is not helpful.
- Order online and complete your draw through a national lab network
- Clear, shareable results you can review with your clinician
- PocketMD guidance to help you plan next steps and follow-up questions
Key benefits of Factor V Leiden Mutation Analysis testing
- 01Explains a possible inherited reason for DVT/PE, especially when a clot seems “unprovoked.”
- 02Clarifies whether your clot risk may rise more than expected with estrogen, pregnancy, surgery, or long travel.
- 03Distinguishes heterozygous from homozygous carrier status, which can change risk discussions.
- 04Helps guide family conversations about whether relatives might consider testing.
- 05Supports decisions about prevention strategies during high-risk periods rather than relying on guesswork.
- 06Reduces confusion when other clotting tests are affected by anticoagulant medications or acute illness.
- 07Gives you a stable, lifelong result that can be revisited as your health situation changes.
What is Factor V Leiden Mutation Analysis?
Factor V Leiden Mutation Analysis is a DNA test that looks for a specific variant in the F5 gene. Factor V is a clotting protein. Normally, your body has “brakes” that slow clotting once it has done its job. One of those brakes is activated protein C (APC).
With the Factor V Leiden variant (often reported as R506Q), factor V becomes more resistant to being turned off by APC. That resistance can tilt your clotting system toward forming clots more easily, particularly in the veins.
The result is usually reported as negative (no mutation detected), heterozygous (one copy of the variant), or homozygous (two copies). Your exact risk depends on your result plus other factors such as prior clots, age, smoking, obesity, immobility, pregnancy, and whether you use estrogen-containing medications.
How this differs from an APC resistance test
Some clinicians start with a functional test called activated protein C resistance. That test measures clotting behavior and can be influenced by other conditions. Mutation analysis directly checks your DNA for the Factor V Leiden variant, which is not altered by anticoagulants, pregnancy, or acute inflammation in the same way functional assays can be.
What the test can and cannot tell you
A positive result means you carry a genetic risk factor for venous clots, but it does not predict exactly if or when you will develop a clot. A negative result does not rule out other inherited or acquired clotting risks. Your clinician may interpret this result alongside your history and, when appropriate, other thrombophilia tests.
What do my Factor V Leiden Mutation Analysis results mean?
Low
Negative (no Factor V Leiden mutation detected)
A negative result means the specific Factor V Leiden variant was not found. Your baseline genetic risk from this variant is not increased, but you can still develop clots from other causes such as surgery, immobility, cancer, pregnancy, estrogen use, or other inherited conditions. If you have had a clot, your clinician may consider additional testing based on your age at the event, whether it was provoked, and your family history.
Optimal
Heterozygous (one copy of the mutation)
A heterozygous result means you carry one copy of the Factor V Leiden variant. Many people with this result never develop a clot, but your risk is higher than average, especially when combined with triggers like estrogen-containing birth control, pregnancy/postpartum, major surgery, or long periods of immobility. Your clinician may focus on situational prevention (for example, around surgery or long travel) and on avoiding or carefully weighing estrogen exposure depending on your history.
High
Homozygous (two copies of the mutation)
A homozygous result means you carry two copies of the Factor V Leiden variant and generally have a higher clot risk than heterozygous carriers. This does not guarantee you will have a clot, but it often changes the intensity of prevention planning, especially during high-risk periods like pregnancy, postpartum, or major surgery. If you have a personal history of DVT/PE, your clinician may discuss longer-term anticoagulation strategies and may consider evaluating for additional clotting risks.
Factors that influence how your result is used
Your personal clot history (none vs one event vs recurrent events) is one of the biggest drivers of next steps. Estrogen exposure (birth control or hormone therapy), pregnancy/postpartum status, smoking, obesity, prolonged immobility, and upcoming surgery can all amplify risk in carriers. Other thrombophilias (such as prothrombin G20210A mutation or antiphospholipid syndrome) can compound risk, so your clinician may recommend broader testing when the clinical picture suggests it. Because this is a genetic result, retesting is rarely needed unless the original result is unavailable or there is a lab documentation issue.
What’s included
- Factor V (Leiden) Mutation
Similar tests and related topics
Frequently Asked Questions
Do I need to fast for a Factor V Leiden test?
No. Factor V Leiden Mutation Analysis is a genetic test, so fasting is not required. You can usually take your usual medications unless your clinician gives different instructions.
Can anticoagulants affect Factor V Leiden Mutation Analysis results?
Anticoagulants generally do not change DNA-based mutation analysis results. This is one reason genetic testing can be useful when functional clotting tests might be harder to interpret during anticoagulation.
What is the difference between heterozygous and homozygous Factor V Leiden?
Heterozygous means you have one copy of the variant; homozygous means you have two copies. Homozygous carrier status is typically associated with higher venous clot risk and may lead to more intensive prevention planning, especially during high-risk situations.
If I have Factor V Leiden, will I definitely get a blood clot?
No. Many carriers never develop a clot. Your overall risk depends on your result plus other factors such as prior clots, estrogen exposure, pregnancy/postpartum, surgery, immobility, smoking, and whether you have other inherited or acquired clotting conditions.
Should my family members get tested if I’m positive?
Sometimes. Testing is more commonly considered for first-degree relatives when there is a strong family history of venous clots or when a relative is considering estrogen-containing contraception, pregnancy planning, or other high-risk situations. Your clinician can help decide whether testing would change medical decisions for your family.
How often should I repeat the Factor V Leiden test?
Usually you do not need to repeat it. Because it is a genetic result, it does not change over time. Retesting is typically only considered if the original report is unavailable or there is a question about the accuracy or documentation of the prior result.
Is Factor V Leiden related to miscarriage or pregnancy complications?
Factor V Leiden is primarily linked to venous clots, and pregnancy itself increases clot risk. Some clinicians consider thrombophilia testing in certain pregnancy histories, but whether this test is appropriate depends on your personal history (including any prior DVT/PE) and current clinical guidelines. It is best used as part of a broader, clinician-led evaluation.