| Description: |
Factor VIII is a co-factor for factor IX in the clotting process. Increases in factor VIII are seen in liver disease and inflammatory states. Hereditary deficiency of factor VIII is hemophilia A, an X-linked recessive bleeding disorder. Affected males have a bleeding diathesis which is related to their factor VIII activity. Severe hemophilia A (<2% activity) is characterized by delayed bleeding after injury and spontaneous deep bleeding (e.g., retroperitoneum, muscles, joints). The best screening test for factor VIII deficiency is the APTT, which is sensitive to factor VIII levels of <30%. Factor VIII is stabilized by von Willebrand factor; patients with von Willebrand’s disease often have low factor VIII levels and prolonged partial thromboplastin times. |
