D-dimers

Last updated: Wednesday, 05, December, 2007

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Item Process
Specimen2 mL blood in EDTA or an appropriately collected citrate blood tube.
Method

A number of methods are in use that employ a monoclonal antibody specific for the degradation products of fibrin which has been crosslinked by Factor XIII.
The techniques vary greatly in their sensitivity from semi-quantitative latex techniques to very sensitive ELISA based assays.

Results are usually issued as D-dimers, and this has largely replaced the previous less specific test for fibrin/fibrinogen degradation products (FDPs) in serum.

Reference Interval
Check with laboratory.
Application

Elevated D-dimers indicate recent or ongoing fibrinolysis, and the assay is used in the investigation of suspected disseminated intravascular coagulation (DIC).

The newer sensitive D-dimer tests have negative predictive value for the presence of deep venous thrombosis in patients with low prior probability (see below). However, the test should not be relied upon in isolation to exclude deep venous thrombosis (DVT).

Interpretation

Levels of the traditional macro D-dimer test are usually increased in DIC, but moderate increases may be seen in patients with malignancy or severe infection.

This test is not recommended for the diagnosis or exclusion of venous thromboembolism. However, a negative result of the sensitive D-dimer test in a patient with a low pre-test probability is useful to exclude deep venous thrombosis as part of a defined clinical management algorithm.

D-dimer levels are also elevated post surgery, so there is no utility in performing the test after recent surgery.

ReferenceHirsch J and Lee A. Blood 2002: 99; 3102-3110.