D-dimer is formed by enzymatic degradation of cross-linked fibrin by plasmin and, therefore, serves as a direct marker of ongoing coagulation with fibrinolysis. The plasma level of D-dimer is used for the evaluation of the patient’s fibrinolytic status. D-dimer concentrations are a beneficial cardiac marker in the diagnosis of deep vein thrombosis and pulmonary embolism and are utilised as control and calibrator in various in vitro diagnostic testing kits. It can also be used as a coating antigen for ELISA or agglutination assays.