Test Overview

A d-dimer test is a blood test that measures a substance that is released when a blood clot breaks up. Doctors order the d-dimer test, along with other lab tests and imaging scans, to help check for blood-clotting problems. A d-dimer test can also be used to check how well a treatment is working.

The test is also known as the fibrin degradation fragment test or the fragment d-dimer test.

Why It Is Done

Doctors use the d-dimer test when a person might have a dangerous blood-clotting problem. These problems include:

• Deep vein thrombosis, a condition in which a blood clot (thrombus) forms in the deep veins of the legs, pelvis, or arms.
• Pulmonary embolism, a condition in which blood flow in an artery in the lung is suddenly blocked.
• Disseminated intravascular coagulation (DIC), a condition that prevents a person's blood from clotting normally.

How To Prepare

No special preparation is required before having this test.

How It Is Done

The health professional drawing your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Put a gauze pad or cotton ball over the needle site as the needle is removed.
• Put pressure to the site and then a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of a problem from having a blood sample taken from a vein.

Results

The d-dimer test measures the amount of a substance that is released when a blood clot breaks up.

The normal values listed here (called a reference range) are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

• A low or normal d-dimer test result means that there is very little of the substance that's released as a blood clot breaks up. Having very little of this substance means that a blood clotting problem isn't likely.
• A higher-than-normal d-dimer level might mean that there is a blood-clotting problem. But a higher level might be caused by some other health problem or by a normal healing process.
• D-dimer levels are often higher than normal in people who have abnormal blood clotting.

What To Think About

D-dimer test results may be affected if the person being tested has rheumatoid arthritis, has had recent surgery or trauma, is on estrogen therapy, or is pregnant.

References

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