The thromboplastin generation test.

Physiological coagulation is dependent on the formation of a powerful thromboplastin within the blood. It is well recognized that coagulation defects, such as that in haemophilia, are due to a failure of the normal thromboplastin mechanism, but lack of knowledge has hitherto prevented any precise or detailed study of these abnormalities. Biggs, Douglas, and Macfarlane (1953a) have shown that three components, normal plasma treated with AI(OH)3, platelets, and normal serum, react to form thromboplastin. Further analysis has shown that two essential substances, antihaemophilic globulin and factor V, occur in the Al(OH)3-treated plasma, while serum contains two factors, factor VII and the Christmas factor, both of which are required for thromboplastin formation (Biggs, Douglas, and Macfarlane, 1953b). These five components-platelets, antihaemophilic globulin, the Christmas factor, and factors V and VII-react together in the presence of CaCl2 to form a labile thromboplastin as powerful as any so far described. A lack of any one of the five produces a coagulation defect associated with abnormal thromboplastin formation. Factors V and VII are usually thought of as