Factor V Leiden



What is factor V Leiden?

Factor V Leiden is a mutation of one of the clotting factors in the blood called factor V. This mutation can increase your chance of developing abnormal blood clots (thrombophilia), usually in your veins.

Most people with factor V Leiden never develop abnormal clots. But some do develop clots that lead to long-term health problems or become life-threatening.

How common is factor V Leiden?

Factor V Leiden is the most common inherited form of thrombophilia. Between 3 and 8 percent of people with European ancestry carry one copy of the factor V Leiden mutation in each cell, and about 1 in 5,000 people have two copies of the mutation. The mutation is less common in other populations. Both men and women can have factor V Leiden. Women may have an increased tendency to develop blood clots during pregnancy or when taking the hormone estrogen. Please discuss with your doctor for further information.


What are the symptoms of factor V Leiden?

The common symptoms of factor V Leiden are:

  • Having a first DVT or PE before 50 years of age.
  • Having recurring DVT or PE.
  • Having venous thrombosis in unusual sites in the body such as the brain or the liver.
  • Having a DVT or PE during or right after pregnancy.
  • Having a history of unexplained pregnancy loss in the second or third trimester.
  • Having a DVT or PE and a strong family history of venous thromboembolism.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

You should contact your doctor if you have any of the following:

  • Have signs or symptoms of a pulmonary embolism, such as chest pain or discomfort.
  • Have signs or symptoms of deep vein thrombosis, such as leg pain and swelling.
  • Have a family history of blood clots or if family members have factor V Leiden. Ask your doctor about the risks and benefits of genetic testing for the disorder.
  • Have had one or more blood-clotting incidents without an apparent cause, especially if you’re under 50.


What causes factor V Leiden?

A blood clot (thrombus) normally forms to stop the bleeding when an artery or vein is damaged, such as when you experience a cut. Clots are formed by chemical reactions between specialized blood cells (platelets) and proteins in your blood (clotting factors). Anti-clotting factors prevent an excessive formation of blood clots.

Normally, factor V is a clotting protein. Anti-clotting proteins break up factor V, keeping it from forming clots when clotting isn’t needed.

Factor V Leiden makes it harder for anti-clotting proteins to break up factor V. This keeps factor V in the blood longer and increases the chance of clotting.

If you have factor V Leiden, you inherited either one copy (heterozygous) or, rarely, two copies (homozygous) of the defective gene. Inheriting one copy slightly increases your risk of developing blood clots. Inheriting two copies — one from each parent — significantly increases your risk of developing blood clots.

Risk factors

What increases my risk for factor V Leiden?

There are many risk factors for factor V Leiden, such as:

  • A family history offactor V Leiden
  • Caucasian or European descent

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is factor V Leiden diagnosed?

Your doctor would suspect a diagnosis of thrombophilia if you have a history of venous thrombosis and/or a family history of venous thrombosis. The diagnosis is made using a screening test called a coagulation screening test or by genetic testing (DNA analysis) of the F5 gene.

How is factor V Leiden treated?

Doctors generally use blood-thinning (anticoagulant) medications, such as warfarin (Coumadin, Jantoven), heparin or low molecular weight heparin to treat people who develop blood clots.

If genetic tests have confirmed that you have factor V Leiden, but you haven’t had any blood clots, then your doctor probably won’t prescribe blood thinners on a regular basis. But you may be given a course of blood thinners to reduce your risk of DVT during high-risk situations, such as having surgery or being hospitalized.

If you have a blood clot, standard initial treatment involves a combination of heparin and warfarin. Your doctor will discontinue the heparin after the initial treatment and continue the warfarin. How long you need to take medication will depend on the circumstances of your thrombosis.

  • This anticoagulant medication works more quickly than warfarin does. It can be administered directly into a vein (intravenously) or under the skin (subcutaneously). You can inject yourself with some forms of heparin, including enoxaparin (Lovenox) and dalteparin (Fragmin). Heparin is considered safe to take during pregnancy.Possible risks of heparin include excess bleeding and allergic reaction. Heparin doesn’t have a standard dose, so it requires regular blood tests and adjustments to get the right dose for you.
  • Warfarin (Coumadin, Jantoven). This anticoagulant comes in pill form, so it’s easier to take than heparin. Warfarin may cause birth defects, so it isn’t usually recommended during pregnancy, especially the first trimester. Bleeding is the most common side effect of warfarin.This drug interacts with many other medications and herbs, so be sure to check with your doctor or pharmacist before taking anything else. As with heparin, there isn’t a standard dose for warfarin, so you’ll need regular blood tests and dose adjustments while taking warfarin.

New oral blood thinners

Three new oral medications have been approved by the Food and Drug Administration for the prevention and treatment of blood clots in certain people. They have an advantage over warfarin, as they don’t require blood test monitoring or dose adjustments. Bleeding complications are the most serious side effect of these medications, but that risk appears to be lower with these drugs than with warfarin:

  • Dabigatran (Pradaxa)
  • Rivaroxaban (Xarelto)
  • Apixaban (Eliquis)

Excessive bleeding caused by these new oral blood thinners can’t be easily reversed. Bleeding caused by heparin and warfarin, on the other hand, can be quickly reversed.

These newer medications also haven’t been well-studied in pregnant women. They may interact with certain medications, but do have far fewer food or drug interactions compared with warfarin.

Talk with your doctor about the risks and benefits for you of new oral blood thinners compared with warfarin.

Follow-up care

If you’re taking an anticoagulant medication that increases the risk of excessive bleeding, your doctor will follow you closely. You’ll have blood tests to help your doctor make sure your blood is capable of clotting enough to stop bleeding if you bruise or cut yourself.

Factor V Leiden during pregnancy

Most women with factor V Leiden have normal pregnancies. However, the risk of blood clots during pregnancy is higher. Pregnant women with factor V Leiden need close medical supervision throughout their pregnancies. There’s no evidence that preventive treatment with blood-thinning medications would be effective enough to outweigh the potential risks of using these drugs during pregnancy or delivery.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage factor V Leiden?

The following lifestyles and home remedies might help you cope with factor V Leiden:

  • Uninterrupted long car or airline trips. When your legs remain still for long periods — more than two hours — your calf muscles don’t contract, which normally helps blood circulate.If you can, try to move around whenever possible on a plane. Drink extra water to prevent dehydration, and avoid alcohol. On a car trip, take periodic breaks and walk around. If you sit for long periods of time for any reason, get up periodically and stretch your legs.
  • Prolonged bed rest, such as during a long illness, or paralysis. Your doctor may suggest the use of compression stockings to keep the blood in your legs moving.
  • Injury or surgery. Injury to your veins or surgery can slow blood flow, increasing the risk of blood clots. General anesthetics used during surgery can dilate your veins, which can increase the risk of blood pooling and then clotting. Let your doctor know that you have factor V Leiden.
  • Oral contraceptives or estrogen replacement therapy. Because these medications can increase the risk of blood clots on their own, be sure to discuss the risks and the benefits of estrogen-containing medications with your doctor if you have factor V Leiden.
  • Being overweight or obese. Being overweight increases the pressure in the veins in your pelvis and legs. Losing weight can lower your risk.
  • Smoking affects blood clotting and circulation. If you’re a smoker, take steps to quit.

Donating blood

One situation you don’t have to avoid if you have factor V Leiden is donating blood. People with factor V Leiden can usually donate blood if interested in doing so.

If you’re taking blood-thinning medications, you can’t donate blood until those medications are fully out of your system. If you’ve taken blood thinners, check with your doctor before donating blood.

Preventing excessive bleeding

If your factor V Leiden requires you to take anticoagulant medication, here are some steps that might help you prevent injury and avoid excessive bleeding:

  • Avoid playing contact sports or engaging in other activities that could result in physical injury. Regular noncontact exercise, such as walking or swimming, is still recommended for good health.
  • Use a soft toothbrush and waxed floss.
  • Avoid shaving cuts by using an electric razor.
  • Be cautious with household tasks involving knives, scissors and other sharp tools.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.


Review Date: August 24, 2017 | Last Modified: August 28, 2017

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