Our April Quick Question arises from discussions with Chad Siniard, MD., University of Alabama at Birmingham Division of Laboratory Medicine and hemostasis author and expert Dave McGlasson. Andexanet Alfa® is the FDA-approved reversal agent for rivaroxaban and apixaban that has become a standard ER treatment for potential anticoagulant overdose. A key consideration is the US cost, approximately $30,000 per dose. Laboratory directors around the US have specified a laboratory assay confirming the presence of anticoagulant therapy prior to Andexanet administration. Our question asks what assay facilities are using and what assay is the most appropriate.