D-Dimer

During fibrinolysis, plasmin breaks down fibrin and fibrinogen. When insoluble fibrin is degraded, a variety of cross-linked fibrin degradation products (XL-FDP) are produced. The smallest cross-linked fibrin degradation product is D-dimer, a fragment that contains one intermolecular cross-link between the gamma chains of two fibrin monomers. This cross-linkage only occurs in fibrin, but not in fibrinogen, so D-dimer is a specific degradation product of fibrin.

Quantitative D-dimer determination aids in detecting the presence and degree of intravascular coagulation and fibrinolysis (the dissolution of the fibrin in a blood clot) and in monitoring the therapy for disseminated intravascular coagulation (nonlocalized clotting in the blood vessels.) D-dimer is also routinely used for excluding deep venous
thrombosis.