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Medical Term:

factor VIII


Definition: in the clotting of blood, also known as: antihemophilic factor A (Brinkhous), antihemophilic globulin (1) (Patek and Taylor), antihemophilic globulin A (Cramer), plasma thromboplastin factor (Ratnoff), plasma thromboplastin factor A (Aggeler), thromboplastic plasma component (Shinowara), thromboplastinogen (Quick), prothrombokinase (Feissly), platelet cofactor (Johnson), plasmokinin (Laki), thrombokatilysin (Leggenhager), and proserum prothrombin conversion accelerator. Factor VIII participates in the clotting of the blood by forming a complex with factor IXa, platelets, and calcium and by enzymatically catalyzing the activation of factor X. Deficiency of factor VIII is associated with classic hemophilia A. Factor VIIIC is the coagulant component of factor VIII which, in normal people, circulates in the plasma complexed with Factor VIIIR (von Willebrand factor), the plasma factor VIII–related protein, a large glycoprotein component that is synthesized by endothelial cells and megakaryocytes, and circulates in the plasma where it binds to arteries that have lost their endothelial cell linings, creating a surface to which platelets adhere. Disorders involving factor VIIIR comprise a heterogenous group of abnormalities called von Willebrand disease. A deficiency of factor VIII can lead to impaired blood coagulation.

Synonym(s): antihemophilic factor A, antihemophilic globulin A, antihemophilic globulin1, plasma thromboplastin factor, platelet cofactor I, prothrombokinase

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