Rivaroxaban and LA?

There are three helpful comments appended to our December 5, 2012 Delta Checks for PT, PTT, Fg, and D-dimer post. One came from “goblue,” whom I surmise is aUniversity of Michigan Wolverines fan (sorry about that South Carolina game): “While administering Xarelto (rivaroxaban), will this give a false positive result on lupus anticoagulant (LA) tests?”

Yes, as rivaroxaban is a direct anti-Xa anticoagulation, it prolongs the PTT and interferes with PTT-based LA testing. On the basis of physiology and mechanism, the DRVVT-based LA assay should still work, however if any one has checked this out in the laboratory, please add your comment here. Geo.