D-Dimer Test and Its Clinical Significance

The D-dimer (or D dimer) is a fibrin degradation product resulting from the breakdown of fibrin by the enzyme plasmin. The D-dimer test is a diagnostic tool used to assess the extent of fibrin degradation in the body. This test can be performed using either serum or plasma samples.

The procedure involves mixing the patient’s blood sample with latex or polystyrene microparticles that are coated with a monoclonal antibody specific to D-dimer. The presence of D-dimer in the sample is detected through the agglutination of these microparticles. Due to the small size of the particles, automated instruments can measure the turbidity of the sample to determine the endpoint of the test.

Elevated levels of D-dimer and Fibrinogen/Fibrin Degradation Products (FDPs) are associated with various medical conditions. These include disseminated intravascular coagulation (DIC), intravascular thrombosis such as myocardial infarction, stroke, venous thrombosis, and pulmonary embolism. Additionally, D-dimer levels may rise following surgery or trauma. Consequently, the D-dimer test is often employed to rule out thrombosis and to assess thrombotic risk.