D-Dimer

D-Dimer is a small protein fragment released when your body breaks down a blood clot. The test measures how much of this fragment is present in your blood, which reflects ongoing clot formation and breakdown.

It is commonly used in the evaluation of symptoms that may be caused by a clot in a vein of the leg or lungs, and it can support the assessment of a widespread clotting disorder. Results are influenced by the type of assay, which may report in fibrin equivalent units or in dimer units.

Clinicians order this test when you have symptoms that could be due to a blood clot, together with a clinical assessment of your overall likelihood. When that likelihood is low or moderate, a result within the expected range can help rule out a new clot without additional imaging.

An elevated result is not specific to a single condition. Many situations can raise D-Dimer, including recent surgery or trauma, infection, inflammation, liver disease, pregnancy, and some cancers. The test can also aid in evaluating and monitoring a serious condition where clotting and bleeding happen at the same time.

Your result is interpreted alongside your symptoms, exam, and clinical risk. A value within the expected range generally makes an acute clot unlikely, while a higher value may prompt imaging studies or closer follow up. The exact next step depends on your overall picture, not the lab number alone.

Age, pregnancy, chronic illness, and recent procedures can influence results and how they are used in decision making. Some care teams apply age-adjusted decision thresholds to reduce false alarms. If you are taking blood thinners, levels can be lower than otherwise expected. Ask your clinician what your result means for you and whether further testing or observation is advised.