Reassessment of a Non-hemophilic Reagent for Factor VIII (AHF) Determination

Performances of two substrates for factor VIII determinations were compared. The first reagent was plasma of patients who had severe hemophilia; the second was normal human plasma artificially depleted in factor VIII activity to which dilute bovine serum was added. Using a partial thromboplastin time assay, the results obtained with this non-hemophilic substrate compared favorably with those obtained with hemophilic substrate. The artificial reagent offers the advantages of specificity, ease of preparation, good stability upon storage, and low cost, and should permit reliable factor VIII determinations in laboratories which do not have access to hemophilic plasma.