F11 and hyperinsulinemic hypoglycemia, familial, 4: The amount of thrombin formed after fibrin formation exceeds the amount of thrombin needed for fibrin formation.36These high TG data are in line with clinical experience reporting hypercoagulability and thrombotic complications in some patients with FXI deficiency when they receive replacement therapy with high-dose FXI.37Moreover, epidemiological data show that high levels of FXI are a risk factor for venous thrombosis.38, 39