Bonnie Jo Taylor, MHS, MT(ASCP)SH, of Shreveport, LA answers inquiries on the American Society for Clinical Laboratory Science Consumer Web Forum. She and I recently collaborated on this question from Dr. J. S.: “Does Pradaxa anticoagulant Rx affect any of the usual tests for anti-phospholipid antibodies?” Our answer was…
Thank you for your question. Yes, Pradaxa (dabigatran) markedly prolongs the partial thromboplastin time (PTT, APTT), which is one of the main clot-based assays for lupus anticoagulant (LAC). Labs are unable to test for LAC when Pradaxa is on board. However, the immunoassays for anti-cardiolipin antibody and anti-beta-2-glycoprotein 1 remain valid, as Pradaxa does not interfere with immunoassay technology. Regrettably, the immunoassays may miss some of the LACs, as the antibodies have great variety in their specificities. Geo.
Actually, all the DOACs
Actually, all the DOACs affect LAC testing. The RVVT assay is now the main assay used for identification of LAC, and all the DOACs have a greater effect on the RVVT than they do on the routine coagulation tests PT & APTT. The DOACs can lead to false positive or false negative LAC, depending on the DOAC and the drug concentration. Do not test for LAC when the patient is on a DOAC.