[Physiologic blood coagulation studies in idiopathic arterial thrombosis]

The prevalence of inherited thrombotic syndromes in the general population appears to be higher than that of inherited bleeding disorders. However, the most important candidates for screening are patients with unexplained thromboembolism at ages of less than 40 years: In 19 children suffering from "idiopathic" arterial thrombosis laboratory screening has been performed.

PT, PTT, TT, platelet count, spontaneous platelet aggregation, von Willebrand-factor, fibrinogen, plasminogen, antithrombin III, protein C, C1-inactivator, alpha-1-antitrypsin, alpha-1-antichymotrypsin, alpha-2-antiplasmin and alpha-2-macroglobulin have been investigated.

Compared to an age matched healthy control group we could demonstrate in children with arterial thrombosis in vitro platelet activation with significant enhanced platelet aggregation, elevated levels of von Willebrand-factor and alpha-1-antichymotrypsin at the onset of disease. Protein C and alpha-2-antiplasmin were significantly decreased. These changes turned back to normal in the following 6 to 9 months. PT, PTT, TT, platelet count, plasminogen, alpha-1-antitrypsin, c1-inactivator and alpha-2-macroglobulin showed no alterations compared to controls.

Platelet activation and alteration of platelet function have been shown in vivo and in vitro to initiate thrombosis. The von Willebrand's VIII molecule is involved in this step. The lowering of protein C levels at the onset of thrombotic diseases is discussed to be due to an increased turnover, whereas the decreased levels of alpha-2-antiplasmin might be a counter-regulation to the thrombotic event, showing an "activated" fibrinolytic system.