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.

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

A health professional uses a needle to take a blood sample, usually from the arm.

How It Feels

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.

Risks

There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.

Results

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

• 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.