FVII activation in the FVIIa functional activity assay. A modification of the functional activity assay was performed using plasma that had been depleted of fibrinogen. Overall reagent concentrations were as described for the functional assay. Plasma was incubated with the functional assay reagents until the reactions were terminated by the addition of an anticoagulant cocktail (see text). The products of the reactions at varying time points were then assayed for FVIIa using the ELISA.