Specialized Testing

Apixaban® Pradaxa® and Xarelto® Anticoagulants

Xarelto® (rivaroxiban) and Eliquis® (apixaban) are direct inhibitors of factor Xa. Pradaxa® (dabigatran) is a direct thrombin inhibitor. These drugs invalidate most functional clotting coagulation tests when being used in a diagnostic setting.

Several functional coagulation tests can be impacted by these newer direct acting oral anticoagulant medications. Functional coagulation tests that may be affected include the Prothrombin Time (PT), activated Partial Thromboplastin Time (PTT), Thrombin Time (TT), Factor VIII Functional Activity assay, Anti-Thrombin 3 Functional Activity assay, Protein S Functional Activity assay, Protein C Functional Activity assay, and most of the tests utilized in the evaluation for lupus anticoagulants, as well as other tests that are incorporated in the various Coagulation Analyzers offered by RML (such as the Lupus Anticoagulant Screen, Lupus Anticoagulant Analyzer, Abnormal PT/PTT Analyzer, and the Hypercoagulation Analyzer).

Some coagulation-relevant tests are NOT affected by these newer direct acting oral anticoagulant medications. These include the Factor V Leiden mutation test, the Prothrombin Gene mutation test, and measurements of Anticardiolipin IgG, Anticardiolipin IgM, Beta 2 glycoprotein IgG, and Beta 2 glycoprotein IgM antibodies. These tests can be ordered individually (i.e., without ordering a more comprehensive panel that constitute portions of the various Coagulation Analyzers offered by RML).

The Protein C Antigen level, the Protein S Free Antigen level, and the Anti-Thrombin 3 Antigen level are not functional clotting tests, and they are usually not affected by these drugs, and so these may be individually ordered as well. Any individual functional clotting test can be ordered, however, none of these tests should be used to measure theraputic effects of these drugs. All our Coagulation Analyzers that might contain such tests should only be performed once the patient has cleared the drugs and their effects. In addition, such Coagulation Analyzers should only be ordered once the patient is in a steady state and no longer actively clotting.

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