in normal plasma , the ratio of the procoagulant activity of factor viii ( viii ( ahf ) ) to that of the von willebrand factor activity ( ristocetin cofactor , viii ( vwf ) ) or factor viii antigen ( viii ( agn ) ) is approximately 1 , but ratios > 1 ( e.g. , viii ( ahf ) > viii ( vwf ) or viii ( agn ) ) may be observed in some patients with von willebrand 's disease and in the `` '' late '' '' posttransfusion plasmas of patients with this disorder .
C0015506
ahf
C0042974
von willebrand 's disease