Laboratory Testing for Hypercoagulability in Patients with Bilateral PE on Apixaban
For patients with bilateral pulmonary embolism being treated with Eliquis (apixaban), hypercoagulability testing should be delayed until after completion of anticoagulation therapy, as testing during active treatment can lead to false results and misinterpretation. 1
Timing of Hypercoagulability Workup
- Hypercoagulability testing should ideally be performed either before initiating anticoagulation or after completing the course of anticoagulation therapy 2
- If the patient is already on apixaban (Eliquis), consider delaying the hypercoagulability workup until at least 2-4 weeks after discontinuation of anticoagulation 1
- Testing during active anticoagulation with apixaban can lead to false-negative results for certain thrombophilia markers 3
Recommended Laboratory Tests for Hypercoagulability
Genetic Tests (Not Affected by Anticoagulation)
- Factor V Leiden mutation 1
- Prothrombin G20210A mutation 1
- MTHFR gene mutation (though clinical utility is debated) 3
Tests Affected by Anticoagulation (Best Performed After Completing Therapy)
- Protein C activity 3
- Protein S activity 3
- Antithrombin III activity 3
- Lupus anticoagulant 1
- Anticardiolipin antibodies 1
- Anti-β2 glycoprotein I antibodies 1
Additional Tests to Consider
- Complete blood count with platelet count (to rule out myeloproliferative disorders) 4
- Homocysteine levels 3
- Factor VIII levels 1
- JAK2 V617F mutation (if myeloproliferative disorder is suspected) 3
Special Considerations with Apixaban
- Apixaban affects many routine coagulation tests, making interpretation difficult during active treatment 5, 6
- Standard PT and aPTT tests have low sensitivity to apixaban and cannot reliably assess its anticoagulant effect 5, 6
- Anti-Xa assays specifically calibrated for apixaban are the most accurate way to measure drug levels if needed 5, 6
Clinical Approach to Testing
- For patients with unprovoked bilateral PE requiring long-term anticoagulation, consider testing for inherited thrombophilias only if results would change management 4
- In younger patients (<50 years) with unprovoked PE, comprehensive thrombophilia testing is more strongly indicated 1
- For patients with recurrent VTE or strong family history of thrombosis, genetic testing should be prioritized even during anticoagulation 3
Common Pitfalls to Avoid
- Performing protein C, protein S, or antithrombin III testing while the patient is on apixaban can lead to falsely low levels 6
- Interpreting lupus anticoagulant testing during anticoagulation therapy can be challenging and misleading 1
- Failing to consider that apixaban itself can affect laboratory coagulation parameters 5, 6
- Testing too early after an acute thrombotic event can lead to false results due to acute phase reactions 3
By following these guidelines for hypercoagulability testing in patients with bilateral PE on apixaban, clinicians can obtain more accurate results that will better inform long-term management decisions.