**8.4. Coagulation markers**

The coagulation activation and fibrinolysis markers are measured to determine the defects in the coagulation system. One of the diagnostic method to estimate the risk of thrombosis is measuring the D-Dimer antigen levels in the plasma. D-Dimers are the degradation products of cross linked fibrinogen generated during fibrinolysis, increase in the plasma D-Dimer antigen levels directly corresponds to an increase in the risk of thrombosis [139]. Prothrombin fragment 1 + 2 (F1 + 2) are the cleavage products generated from prothrombin and F1 + 2 levels are measured to diagnose the risk of thrombosis, sepsis and DIC [140]. Free thrombin that moves away from the site of clot formation forms a complex with antithrombin III and the complex is known as TAT complex. TAT complex is used to measure the risk of thrombosis in patients with multiple trauma, liver dysfunction and septicemia [141, 142]. Coagulation factors like FXIII, Protein S and Antiphospholipid antibodies are also quantified by immune assays to measure the alterations in coagulation system [141].
