Discrepancy between One-stage and Two-stage Assay of Factor VIII:C

Abstract

Two methods (1-stage and 2-stage) are commonly used for the assay of [human] factor VIII clotting activity (VIII:C). Collected data from 7 separate studies of VIII:C assay were presented which showed that these methods do not give the same result when comparing concentrates and plasma. On average, 2-stage assays detect 20% more VIII:C activity in concentrates as compared to plasmas than do 1-stage assays.