von Willebrand's disease and hemophilia are associated with diminished thromboxane A2 (TXA2) formation in clotting whole blood.

Von Willebrand's disease (vWd) and hemophilia are associated with hemorrhagic diathesis and disturbances in platelet aggregation to vessel wall. We compared the time course of thromboxane A2 (TXA2) formation by platelets during spontaneous clotting of blood of patients with von Willebrand syndrome and from patients with hemophilia A or B with that of healthy controls which were matched for sex, age and serum lipid status. In clotting blood of healthy females the TXA2 production rose at 37 degrees C in 60 min up to 228.2 +/- 32.3 ng/ml. In patients with vWd the TXA2 production at 60 min was significantly lower (129.1 +/- 26.7 ng/ml, p < 0/05). In hemophilia type A and B the TXA2 formation after 5-30 min was significantly diminished in comparison to healthy male controls (p < 0.05). From the diminished amount of TXA2 formed during spontaneous clotting of whole blood we conclude that the activation of platelets of patients with von Willebrand syndrome or hemophilia type A and B is diminished as compared to healthy controls possibly caused by reduced formation of thrombin in the blood coagulation process.