Your Resource for all Things Relating to Factor V Leiden

What are the symptoms of Factor V Leiden thrombophilia?

The Factor V Leiden mutation itself does not display any outward symptoms that you would be able to detect to suggest that you have the disorder prior to developing a blood clot.

Therefore, the first indication that you may have Factor V Leiden is when you or someone in your family develops a venous blood clot or an unexplained pregnancy loss.

  • Symptoms that indicate you may have Factor V Leiden and the severity of those symptoms vary greatly among individuals.
  • An estimated 90% of individuals who carry the Factor V Leiden gene never develop abnormal blood clots and may never know they have the disorder.
  • On the other hand, some individuals begin having recurring blood clots before 30 years of age.

Symptoms that indicate you may have Factor V Leiden include:

  • Having a deep vein thrombosis (DVT) or pulmonary embolism (PE) before 50 years of age.
  • Having a strong family history of venous thromboembolism.
  • Having recurring DVTs or PEs.
  • Having venous thrombosis in unusual or less common sites in the body. This would include superficial veins of the leg, veins carrying blood from the digestive organs and spleen to the liver, veins carrying blood away from the liver, and veins supplying the brain.
  • Having a DVT or PE during or right after pregnancy.
  • Having a history of unexplained pregnancy loss in the second or third trimester.

Important Risk Factors or "Triggers" for Developing an Abnormal Blood Clot

Should you be diagnosed with Factor V Leiden, here are some common risk factors that, combined with Factor V Leiden, increase your chances of developing or “triggering” an abnormal blood clot:

Genetic Risk Factors

  • Having two copies of the Factor V Leiden gene (called homozygous) versus having only one copy of the gene (called heterozygous) can significantly increase your risk of abnormal blood clots.
  • The presence of other genetic blood clotting disorders in addition to Factor V Leiden such as a prothrombin gene mutation or deficiencies of natural proteins that prevent clotting (such as antithrombin, protein C and protein S) can increase your risk.

Circumstantial / Acquired Risk Factors

  • Hospitalization for illness or surgery, especially hip or knee replacement surgery or surgery of the pelvis.
  • Severe trauma such as a car accident
  • Obesity
  • Prolonged bed rest or confinement to a wheelchair
  • Immobilization – long periods of not moving (like sitting on a long airplane ride) can increase the risk of leg clots, especially with legs crossed.
  • Non-O blood group – abnormal blood clots are more common in people who have blood types A, B, or AB compared to those with type O blood.
  • Cancer and cancer treatments
  • Dehydration
  • Injury to a vein that may have been caused by a broken bone or a severe muscle injury.
  • A family history of blood clots.
  • Long-term diseases such as heart and lung conditions, or diabetes
  • Advanced Age – the risk of blood clots increases with age although a blood clot can occur at any age.
  • Pregnancy, which includes up to three to six months after the baby is born.
  • Use of birth control methods that contain estrogen, such as the pill, patch, or ring.
  • Hormone replacement therapy that contains estrogen.
  • Smoking – it affects blood flow and circulation which can raise your risk for a clot.
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