PTT Reagent LA Sensitivity in Mixing Studies

Hello George, My name is Marcelo Gonçalves, clinical pathologist from Hematology Department of Hermes Pardini Laboratory, Brazil. I would like to ask what kind of activated partial thromboplastin time (APTT, PTT) reagents should be used in APTT mixing studies (high or low responsiveness to LA)? Thank you for your attention.
Dr. Marcelo Luide Pereira Gonçalves

Thank you, Dr. Gonçalves, for your question, which we address in a recent publication,Fritsma GA, Dambitzer, FR, Randhawa A, Marques MB, Van Cott EM, Adcock-Funk D, Peerschke EI. Recommendations for appropriate activated partial thromboplastin time reagent selection and utilization. Am J Clin Pathol 2012; 137: 904-8. While we recommend using low- or intermediate-sensitivity PTT reagents when performing routine laboratory screening for coagulopathies or when monitoring unfractionated heparin, we recommend reagents that possess high lupus anticoagulant (LA) sensitivity when performing mixing studies. Two that are available in the US, for example, are Siemens Actin FSL and Instrumentation Laboratories HemosIL aPTT-SP. Again, thank you for your question, and watch here for comments, in case our participants have additional suggestions or examples.