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RVV and Hemophilia

Here is an interesting question from someone at United Lab:

Dear George,
I have spiked hemophilic plasma with crude Russell viper venom (RVV). The TEG shows that an 81-minute R value is corrected to 3.2 minutes. This suggests that RVV generates a clot without factor VIII. Your comment please.

Thank you for your question. Yes, Russell viper venom activates coagulation at the level of factor X, bypassing the requirement for normal factor VIII activity. Factor deficiencies that prolong the RVV assay are factors X, V, prothrombin (II), and fibrinogen (if severely deficient). By the way, the Russell viper, native to India, is considered one of the most venomous and dangerous snakes in the world.

We don’t use the RVV assay much these days, but we do use the dilute Russell viper venom time test (DRVVT) routinely as a screening and confirmatory test for lupus anticoagulant. Geo.

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