hematology and oncology
Elevated Factor VIII, IX, and XI Levels
Introduction
Increased levels of factors VIII, IX, and XI are risk factors for venous thromboembolism (VTE). While these levels are genetically determined, elevated levels of factor VIII can occur in chronic inflammation and other systemic disorders. Treatment is with anticoagulation for VTE and, in the case of elevated factor VIII, specific treatment for underlying disorders. Factors VIII, IX, and XI are clotting proteins made primarily in the liver.Factor VIIIcirculates in an inactive form bound tovon Willebrand factor(VWF) until blood vessel injury activates it and separates them. FreeFactor VIIIthen interacts withfactor IXto facilitate clotting. activity > 150 IU/L was associated with a nearly 5-fold increased risk of VTE ( General references ). Elevated and XI antigen levels are also associated with an increased risk of VTE ( General references ). However, the Longitudinal Investigation of Thromboembolism Etiology study also found that levels have also been associated with an increased risk of VTE ( General references ). 