Changes Induced by Venous Stasis on Factor VIII Activities (VIII:C; VIIIR.AG; VIIIR:WF) in Different Clinical Conditions

F.VIII related activities (coagulant-VIII:C, antigen-VIIIR:AG, v.Willebrand factor-VIIIR.WF) before and after venous occlusion (VO) were investigated in pregnant women, in women on the pill, and in men with atherosclerosis obliterans, “ean basal values of atherosclerotic patients were not different from healthy male’controls. A concordant rise in all the three activities was seen after VO in both groups without any change in the ratios between them. Basal values of women on long-term hormonal contraception were also comparable with those of a control group, while a group of third trimester pregnant women showed high values for all components, and very high ones for VIIIR:AG, with striking increases in AG/C and AG/WF ratios. Following VO, strictly concordant variations in the three activities were observed in all cases, so that ratios remained always unchanged, at their different levels.

The results are consistent with the hypothesis of a “complete” F.VIII released activity, induced by venous stasis in these conditions. Pregnancy has quite different effects on F.VIII in comparison with estro—progestinic treatment. No variations seem to be associate! with occlusive arterial disease.