Blood Thinners and Nutritional Supplements

Millions of people worldwide are taking blood thinners for hypercoagulation. Millions of others are prescribed aspirin (a blood thinner) to prevent arteriosclerosis, despite side effects such as gastric irritation and bleeding.

Can herbs such as gingko and nutritional supplements such as vitamin E interact with blood thinners? The answer is Yes, and you should know about it.


Hypercoagulation 101

The following Frequently Asked Question is excerpted from the October 15, 1997 issue of American Family Physician.


What does hypercoagulation mean?

When you get a cut, your body stops the bleeding by forming a blood clot (a thickened mass). Substances in your blood (called proteins) work with tiny particles (called platelets) to form the clot. Forming a clot is called "coagulation." Coagulation helps when you are injured because it slows blood loss. However, your blood shouldn't clot when it's just moving through your body. If blood clots inside your blood vessels, it's called "thrombosis" or "phlebitis." The tendency to clot too much is called "hypercoagulation," and it can be very dangerous.


Why is hypercoagulation dangerous?

When abnormal clots occur, they usually form inside veins (the vessels that carry blood to the heart). A clot inside a blood vessel is called a "thrombus." Sometimes the thrombus can travel in the bloodstream and get stuck in your lungs. This kind of clot, called a "pulmonary embolus," keeps blood from getting to your lungs. A pulmonary embolus can be life-threatening.

A clot that blocks a blood vessel in the brain can cause a stroke. A clot in a blood vessel in the heart can cause a heart attack. Blood clots can cause some women to miscarriage.


What causes hypercoagulation?

In addition to proteins that help with clotting, your blood also has some proteins that prevent clotting. Some of these are called protein C, protein S and antithrombin III. Usually, these anti-clotting proteins are strong enough to stop clotting in the veins when it shouldn't happen.

However, certain situations or risk factors can make it easier for your blood to clot too much. These situations include the following:

• Sitting on an airplane or in a car for a long time
• Having prolonged bed rest (several days at a time)
• Having surgery
• Having cancer
• Being pregnant
• Using birth control pills

Some people are born with a tendency to develop clots. This tendency is inherited (it comes from your parents). Most of the time, increased clotting happens because protein C in the blood isn't doing its job properly. This condition is called "APC resistance" or "factor V Leiden."

In some people, the blood clots too much because their body doesn't make enough protein C or protein S. This is called "protein C deficiency," or "protein S deficiency," depending on which protein is missing. A few people don't have enough antithrombin III, or have antithrombin III that doesn't work. Some people have an extra protein in their blood that causes too much clotting. This protein is called "lupus anticoagulant." Although it is called "anticoagulant," it actually causes clotting.
 Hypercoagulation has a few other causes, but those causes are rare.

How do I know if I have a problem with hypercoagulation?

Your doctor might think that you have a problem with hypercoagulation if you have any of the following:

• You have relatives with abnormal or excessive clotting
• You had an abnormal clot when you were young
• You got clots when you were pregnant or were using birth control pills
• You have had several unexplained miscarriages

If your doctor suspects you have hypercoagulation, tests can measure APC resistance, protein C, protein S and antithrombin III in your blood and can check for the lupus anticoagulant protein. The tests will also show if your proteins are working the right way.

Can hypercoagulation be treated?

Yes. Several medicines can thin your blood and make it less likely to clot. Some people with hypercoagulation only need to take blood thinners when they're in a situation that makes them more likely to form clots--like when they're in the hospital recovering from surgery, when they're in a car or airplane for a long time and when they're pregnant. Other people need to take medicine for the rest of their lives. Your doctor will decide which group you're in.

What medicines can I take?

The two most common blood thinners are called heparin and warfarin. Your doctor will probably give you heparin first, because heparin works right away. Heparin must be injected with a small needle under the skin. Once the heparin starts working, your doctor will probably have you start taking oral warfarin. Warfarin takes longer to begin working.

What are the side effects of these medicines?

Both medicines can cause you to bleed more easily. You might notice that, if you cut yourself, the blood takes longer to clot. You might bruise more easily. If you have any unusual or heavy bleeding, call your doctor.

Warfarin has a stronger effect on some people than on others. If you take warfarin, your doctor will want to check you often with a blood test called the PT-INR (International Normalized Ratio). This test will tell your doctor how well the warfarin is working. Some other medicines can make warfarin more or less strong. Ask your doctor before you take a new medicine, even nonprescription medicines and vitamins.

If you're pregnant, you shouldn't take warfarin. Warfarin can cause birth defects. Instead, you must use heparin until after you have your baby. If you want to get pregnant and you're already taking warfarin, talk with your doctor about changing to heparin. Sexually active women who take warfarin should use birth control.