| Description: |
Factor V is a clotting co-factor which in its activated form along with factor Xa and phospholipid comprise the prothrombinase complex, which converts prothrombin to thrombin. Factor V circulates in the blood as a zymogen and is activated by thrombin. The half-life of factor V is 36 hours. Eighteen to 25% of the pool of factor V is stored in platelets. Factor V is inactivated by protein C. The prothrombinase complex represents the convergence of the extrinsic and intrinsic clotting pathways. Thus, deficiencies of factor V (or factor X) result in prolonged prothrombin and partial thromboplastin times. Congenital factor V deficiency is a rare autosomal recessive disease. Acquired factor V deficiency most commonly occurs because of antibodies (inhibitors) against factor V. Inhibitors have been described following surgical use of topical bovine thrombin (which contains factor V) and with aminoglycoside antibiotic use. Often the etiology is not apparent. |
