D-dimer test
A d-dimer test is a blood test that measures a substance (fibrin) that is released as a blood clot breaks up. D-dimer levels are often higher than normal in people who have a blood clot, but other conditions also may cause high d-dimer levels.
A low d-dimer test result means that a blood clot in the leg or the lung (pulmonary embolism) is unlikely.
Why is a d-dimer test 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 is a d-dimer test done?
A health professional uses a needle to take a blood sample, usually from the arm.
How do you prepare for a d-dimer test?
No special preparation is required before having this test.
What do the results of a d-dimer test mean?
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.
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