D-dimer, plasma mass concentration (quantitative)

Why Is This Test Done?

Your healthcare provider may order a D-dimer test to check for signs of blood clots (thrombosis) in your veins or arteries. It’s often used in conditions like deep vein thrombosis (DVT), pulmonary embolism, or other clotting disorders. The test can also help determine if an existing clot has resolved.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s done via a blood draw, but this depends on your healthcare provider’s instructions. If you’re taking blood thinners, let your provider know before the test.

How the Test Works

A small needle is inserted into a vein (often in your arm), and blood is drawn into a test tube. The blood is then analyzed in a lab to measure D-dimer levels. The test is typically done on plasma, the liquid part of blood that contains clotting factors.

Possible Results and Interpretation

Results are not given in absolute numbers but compared to your baseline or clinical context. High levels of D-dimer often suggest recent clot formation, while low or normal levels may indicate no active clotting. Your provider will discuss the meaning of your specific result in relation to your symptoms and medical history.