the variability of laboratory findings in von willebrand 's disease ( vwd ) was evaluated by performing serial studies of bleeding time ( bt ) , factor viii coagulant activity ( viii : c ) , factor-viii-related antigen ( viiir : ag ) and ristocetin cofactor ( viiir : rcof ) in 50 individuals from 25 families with this disorder .
C0019080
bleeding
C0042971
ristocetin cofactor