Compared with the euthyroid controls, patients with hyperthyroidism and SCHyper present significantly increased levels of fibrinogen, factor IX, von Willebrand factor, antithrombin III and plasminogen activator inhibitor-1 and decreased levels of factor X, tissue-type plasminogen activator, and tissue factor pathway inhibitor antigen, suggesting a reduced fibrinolytic capacity (22, 23). This evidence concerns the gene SERPINE1 and hyperthyroidism.