Thrombin-antithrombin (TAT) complexes formed following the neutralization of thrombin by antithrombin III (AT) have been used as a surrogate marker for thrombin generation. High plasma level of TAT complexes has been suggested to alter hemostatic activation in argentine hemorrhagic fever, chronic dialysis patients, and toxemia of pregnancy.

Whereas low plasma level of TAT complexes is found in type 1 (insulin-dependent) diabetes, neonatal respiratory distress syndrome, and primary untreated cancer. TAT complexes are a useful marker to predict morphological changes in chronic aortic dissection.

Thrombin-antithrombin complex (TAT) is a sensitive marker for thrombin formation, and α₂-plasmin inhibitor-plasmin complex (PIC) is a marker for fibrinolysis.