Factor VIII Inhibitor Assay
Some questions about factor VIII inhibitors from Kelly Townsend at TriCore:
- When performing Factor VIII inhibitor testing, at what activity level do you either treat the specimen to inactivate patient factor VIII or not perform the assay?
- If you do treat the sample, exactly what do you do (what temp and how long)?
- Does your protocol differ if the patient has hemophilia and has an inhibitor because he’s been getting product versus a non-hemophilia patient with an acquired inhibitor?
Thanks for any advice you can give,
Kelly Townsend, MT(ASCP)SH
TriCore Reference Laboratories
Albuquerque, NM
Hello, Kelly, good to "hear" from you. I checked your question with my colleagues Laura Taylor and Patti Tichenor in the University of Alabama at Birmingham special coagulation laboratory. At UAB we do not perform a Bethesda titer when the factor VIII activity level is above 30%, same for both allo- and autoantibodies. If the factor VIII level is borderline and the factor VIII assay shows non-parallel inter-dilution results, we perform the titer. We don't inactivate the factor VIII when over 30%. I'll be interested to see whether other experts inactivate the factor, and what can be accomplished by this step. Geo.
