A Simple One-Stage Method for the Assay of Antihemophilic a Factor with a Comment on the Plasma Level of this Factor in Hemophilia A

A simple and reliable method for the assay of antihemophilic A factor is greatly needed both for diagnostic purposes and for the guidance of adequate transfusion therapy in hemophilia A. The great number of methods proposed reflects the difficulty in arranging a test system which combines accuracy and reproducibility with simplicity and quick performance. The thromboplastin generation test (Biggs & Douglas 1953) provided a useful method for the differentiation between hemophilia h and other blood clotting anomalies. The various modifications of this method (Biggs, Eveling & Richards 1955 ; Pitney 1956; Biggs 1957) are probably among the most reliable and accurate tests for the quantitative assay of antihemophilic A factor. Unfortunately, however, they are all relatively complicated and time-consuming. Modifications of the prothrombin consumption test (Graham, Collins, Godwin & Brinkhous 1951; Quick & Hussey 1956) and of the thrombin generation test (Wolf 1956), which all seem to give sensitive assay procedures, are also rather laborious and time-consuming.