Effect of Russell's Viper Venom (Stypven) on Stuart Clotting Defect

Abstract

Summary

It is shown that Russell's viper venom (Stypven) does not correct the prolonged one-stage prothrombin time of patient with a congenital hemorrhagic diathesis previously thought to be deficient in factor VII. The factor deficient in this patient which is referred to as the Stuart factor, is readily distinguishable from both the Prower factor and factor VII since the prolonged prothrombin times of plasma deficient in either of these two factors are completely corrected by Stypven. The finding that Stypven does not correct the clotting defect of Stuart factor deficient plasma implies that certain modified one-stage “specific” assay methods for prothrombin using Stypven as a source of factor VII are not, in fact, specific, and measure both prothrombin and Stuart factor.