What Is Factor V Leiden?

Factor V Leiden is a genetic abnormality or mutation that affects a blood clotting factor. It increases the likelihood of forming blood clots, especially in the lungs or lower extremities, which can be a high-risk and life-threatening situation.

Although Factor V Leiden can occur in anyone, women have a higher incidence of clot formation, especially if they are pregnant. Additionally, if a person has one copy of the abnormal gene, the risk of forming clots is not high, but if they have two copies—one from each parent—the risks increase significantly.

A number of situations have been identified that increase the risk of forming blood clots in people with Factor V Leiden, including:

• Extended periods of immobility
• Oral contraceptives
• Hormone replacement therapy
• Pregnancy
• Surgical procedures
• Fractures

Blood Clotting Issues

Blood clotting issues in people with Factor V Leiden develop due to a genetic alteration that makes Factor V, a protein with a crucial role in blood clotting, resistant to the action of activated protein C, a natural anticoagulant protein.

Normally, activated protein C deactivates Factor V to prevent unnecessary and prolonged clotting. But in those with this mutation, Factor V remains active for longer than it should, which promotes the formation of abnormal clots, especially in the deep veins.

Many people with this mutation have no obvious symptoms and may not know they have it until they experience a thrombotic event. When symptoms do appear, they are usually related to the formation of abnormal clots, such as swelling, redness, pain, or a feeling of warmth in one leg. There may also be sudden shortness of breath, chest pain, and tachycardia if a pulmonary embolism is developing.

In women, signs may also manifest as complications during pregnancy, such as miscarriages, preeclampsia, or fetal growth restriction.

Additionally, there is a greater risk of symptoms if other risk factors are present, such as the use of hormonal contraceptives, smoking, prolonged immobility, or recent surgeries.

Diagnosing Factor V Leiden

The diagnosis of Factor V Leiden is based on clinical suspicion, especially in people who have had deep vein thrombosis or pulmonary embolisms with no apparent cause, as well as those with a family history of thrombotic events at a young age.

It’s also important to consider testing for it in women who have had recurrent obstetric complications.

In these cases, a doctor may order specific lab tests that evaluate the function of the clotting system, such as an activated protein C resistance test.

If this test suggests resistance, the diagnosis is confirmed with a genetic test that directly detects the presence of the mutation in the Factor V gene.

This lab test can identify whether a person is heterozygous (has one copy of the mutation) or homozygous (has two copies), which has implications for the level of thrombotic risk.

A preventive diagnosis can also be made in the immediate family members of people who have already been diagnosed, especially if they are going to be in high-risk situations like surgeries, hormonal treatments, or pregnancies.

Reaching a genetic confirmation allows for more informed medical decisions regarding the prevention and management of thrombotic events.

Treatment for Factor V Leiden varies depending on each person’s level of thrombotic risk. In many cases, especially in heterozygous individuals who have never had a thrombosis event, permanent anticoagulant treatment is not usually required. However, it’s important to have medical supervision and take preventive measures in high-risk situations such as long flights, surgeries, pregnancy, or the use of hormonal contraceptives. The use of temporary anticoagulants is often indicated in these contexts.

For people who have already had one or more episodes of deep vein thrombosis or pulmonary embolism, especially in homozygous individuals, treatment often includes the administration of prolonged or lifelong anticoagulation. It is also recommended to adopt lifestyle changes that reduce the risk of thrombosis, which can include maintaining a healthy weight, avoiding smoking, and getting regular physical activity.

The management of Factor V Leiden must be individualized and constantly evaluated to balance the risk of thrombosis and the risk of bleeding associated with the use of anticoagulants.

At the Vascular, Arterial, and Venous Disease department at ABC Medical Center, we can provide you with specialized care. Contact us!