Factor VIII procoagulant antigen levels in normal pregnancy and preeclampsia.

It has been suggested that the basis for the marked discordance in factor VIII parameters in preeclampsia is the result of proteolysis of the factor VIII procoagulant component (VIII:C) owing to activation of the coagulation system. To investigate this further, levels were compared of factor VIII:C and VIII:C (Ag), the immunologic equivalent of the procoagulant activity, in a series of preeclamptic patients and patients with uncomplicated pregnancies. No significant difference in the mean (+/- SD) level of factor VIII:C or VIII:C (Ag) could be detected between these groups. Our results do not support proteolysis of factor VIII:C as a mechanism to account for the discordant levels of the factor VIII parameters in preeclampsia.