D-dimer plasma concentration (quantitative)

What Is D-Dimer?

D-dimer is a byproduct formed when fibrin, a protein involved in blood clotting, is broken down. Elevated levels can suggest recent clot formation, but they can also appear in other conditions like inflammation or pregnancy. This test is often used alongside other tests to guide decisions about treatments like blood thinners or further imaging.

Why Might Your Doctor Order This Test?

Your doctor may order a D-dimer test if you have symptoms like unexplained bruising, leg swelling, or shortness of breath that could indicate a blood clot. It’s also used in certain situations to rule out clots, such as before surgery or in people with suspected pulmonary embolism (a clot in the lungs).

How Is the Test Done?

A blood sample is taken from a vein in your arm. The blood is processed to separate plasma, and the D-dimer level is measured using a sensitive lab technique. The test usually takes a few hours to complete, and results are reported as a concentration value.

What Do Results Mean?

Results are interpreted based on your symptoms, medical history, and other tests. Very low levels may mean no active clotting is present, while very high levels could raise concern for clots. However, a normal result doesn’t guarantee you don’t have a clot—it just means your blood isn’t breaking down clots at an unusually high rate.