[Factor XII (Hageman factor) deficiency: a risk factor for development of thromboembolism. Incidence of factor XII deficiency in patients after recurrent venous or arterial thromboembolism and myocardial infarction].

103 patients suffering from recurrent venous thrombosis, recurrent arterial thromboembolism and/or recurrent myocardial infarction and 50 healthy subjects were tested for Hageman factor (F XII) coagulant activity and antigen. Among the 103 patients we identified 15 subjects with F XII deficiency (15%), 3 with protein C deficiency (3%) and 3 with protein S deficiency (3%). Combined F XII and protein C, protein S or antithrombin III deficiency was not observed. The 103 patients were divided into subgroups according to the type of thrombotic complication. Among patients with exclusively recurrent venous thromboembolism 8% (p = 0.153) were deficient in F XII. Among patients suffering from recurrent arterial thromboembolism and/or myocardial infarction, the incidence of F XII deficiency was significantly higher (20%, p < 0.003). In 67% of the patients with F XII deficiency a positive family history of thrombosis could be established. In contrast, only 32% (p = 0.043) of all venous and 28% (p = 0.019) of all arterial thrombosis patients had a positive family history. We believe that reduced levels of F XII should be considered as a risk factor in the development of thromboembolism. Consequently, more attention should be payed to the measurement of F XII when evaluating thromboembolic risk factors especially in cases of recurrent arterial thromboembolism and/or myocardial infarction.