role of factor VIII in blood coagulation

Last reviewed 01/2018

Factor VIII acts as follows:

  • acceleration of the rate of cleavage of factor X by activated factor IX - accelerates the maximal velocity by 1000-fold (1)

  • factor VIII circulates in the plasma in a noncovalent complex with von Willebrand factor, vWF. VWF enhances factor VIII synthesis, protects it from proteolysis, and concentrates it at sites of active haemostasis (von Willebrand factor binds to subendothelial matrix proteins and adherent platelets).


  • Hoyer LW (1994). Hemophilia A. NEJM, 330(1), 38-46.