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. To learn more, see the topic Deep Vein Thrombosis.
- Pulmonary embolism, a condition in which blood flow in an artery in the lung is suddenly blocked. To learn more, see the topic Pulmonary Embolism.
- 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 on the site and then put on 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.
There is very little chance of a problem from having a blood sample taken from a vein.
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.
Less than 250 micrograms per liter (mcg/L)
Less than 1.37 nanomoles per liter (nmol/L)
- 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
Other Works Consulted
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerJeffrey S. Ginsberg, MD - Hematology
Current as ofFebruary 20, 2015