Clotting disorders: Factor V Leiden and blood clots

Oct 26, 2017 | Mayo Clinic Hematology Staff | @mayoclinichematologystaff

Dr. Marshall Editorial_2

As many as 1 in 20 Caucasians carry a gene mutation called factor V Leiden. This mutation can increase your chance of developing abnormal blood clots (thrombophilia) ─ usually in your veins.

Factor V Leiden is an inherited, heterozygous disorder, where one gene comes from dad and one comes from mom.

“Factor V Leiden may increase the risk of a blood clot from anywhere from two to five times, but it is important to compare that to the general population’s risk,” says Ariela Marshall, M.D., a Mayo Clinic hematologist. “If you take someone in their 30s or 40s, the risk of a blood clot is about 1 in 10,000, so you multiply that by four or five times, it is still only 4 or 5 in 10,000.”

However, Dr. Marshall explains the risk number changes with age. Adults in their 50s and 60s have a baseline blood clot risk of 1 in 1,000, so someone with factor V Leiden would be 4 or 5 in 1,000. For adults in their 70s and 80s, the normal risk for a blood clot may be as high as 1 in 100.

Age is just one risk factor for blood clots. Others include:

  • Smoking
  • Being overweight
  • Sedentary lifestyle
  • Estrogen-containing birth control pills
  • Pregnancy
  • Flying
  • Previous blood clot

According to Dr. Marshall, each risk factor a person has compounds the chance of getting a blood clot.

“Say, for instance, you have a smoker who is over 35 but skinny, you have a slightly increased risk of blood clots,” Dr. Marshall says. “But if you take someone who is 70, overweight and smokes, they are at a much higher increased risk of blood clots. If a person also has factor V Leiden, you then multiply all of these risk factors by another four or five times.”

Legs and lungs are the two most common areas for blood clots.

To recognize when you have a blood clot, note these warning signs:

  • New pain and swelling in the legs ─ ongoing pain that is typically in one leg
  • Redness
  • Sudden onset of shortness of breath not related to exercise

“If you have had a previous clot, you are more likely to get another blood clot in the same spot because of the remaining blood vessels abnormality,” Dr. Marshall says.

Treating a clotting disorder may not be as worrisome as you’d expect.

“We do not actively treat clotting disorders, unless they have had a blood clot,” Dr. Marshall says. “What we do want to do, is council our patients about how to mitigate the other risk factors like smoking, weight management and living healthy lifestyles.”

Patients with clotting disorders are actively managed during major surgical procedures with low doses of blood thinners.

“It is important to know our patients have a clotting disorder so they can be properly managed during procedures or trauma,” Dr. Marshall says. “But the best thing a person can do is manage the controllable risk factors as best they can.”

On Novermber 2nd, 2017, we discuss how clotting disorders affect women differently than men.


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