Thrombin generation: what have we learned?

Thrombin is a pivotal player in the coagulation system. In clotting blood a transient wave of thrombin appears after a lag time. Clotting occurs at the start of the wave. The amount of thrombin formed reflects the function of the hemostatic system much better than the clotting time does: "The more thrombin the less bleeding but the more thrombosis, the less thrombin the more bleeding but the less thrombosis" has been shown to hold for congenital and acquired tendencies to venous thrombosis and bleeding and under all variants of antithrombotic treatment. The situation with arterial thrombosis is less clear. Calibrated automated thrombinography (CAT) allows quantitative assessment of the thrombin generation (TG) curve in platelet poor as well as in platelet rich plasma. Procedures to measure TG in whole blood and at the point of care are under development. TG measurement in platelet rich plasma underlines the close cooperation between platelets and the clotting system and challenges the traditional division between primary and secondary hemostases.