1. It has been shown that Russell viper venom in the presence of lipoid cofactor can clot hemophilia A plasma, hemophilia B plasma and proconvertin deficient plasma within 5 seconds. It is unable to clot proaccelerin deficient plasma rapidly. Thus the clotting behavior of venom-lipoid is similar to convertin.
2. A rapid presumptive test for hypoproconvertinemia is simply to do a Quick clotting time with brain thromboplastin and then with viper venom. Proconvertin deficient plasma will give a prolonged brain thromboplastin time but a normal venom time. Prothrombin or proaccelerin deficient plasma will give long clotting times with both agents.
3. The observation that Russell viper venom acts independently of the proconvertin content of plasma explains the differences between the venom and brain thromboplastins. It also explains the failure of venom to measure the full effect of dicumarol administration.