Hypercoagulable Workup on Eliquis (Apixaban)
Direct Answer
Perform the hypercoagulable workup while the patient remains on apixaban without interruption, as apixaban does not interfere with most thrombophilia testing and stopping anticoagulation poses significant thrombotic risk. 1
Testing Strategy While on Apixaban
Tests That Can Be Performed On Therapy
The following hypercoagulability tests remain valid while on apixaban and should be obtained without drug interruption:
- Factor V Leiden mutation - genetic testing is unaffected by anticoagulation status 1
- Prothrombin G20210A mutation - genetic testing is unaffected by anticoagulation status 1
- Antiphospholipid antibodies (anti-cardiolipin antibody, lupus anticoagulant, anti-beta-2-glycoprotein I) - can be checked on therapy, though lupus anticoagulant may be affected 1
- Platelet count - to assess for heparin-induced thrombocytopenia or other thrombocytopenic conditions 1
Tests Affected by Apixaban
The following tests are significantly affected by apixaban and should ideally be performed after drug clearance:
- Protein C levels - apixaban interferes with functional assays 1
- Protein S levels - apixaban interferes with functional assays 1
- Antithrombin III levels - apixaban interferes with functional assays 1
Critical Timing Considerations
If Testing Must Be Done Off Apixaban
Apixaban has a half-life of approximately 12 hours (extending to 17 hours in elderly patients and those with renal impairment), requiring at least 48-72 hours (4-5 half-lives) for adequate drug clearance before testing protein C, protein S, and antithrombin III. 2, 3
- Discontinue apixaban at least 48 hours before testing for moderate-risk situations 3
- Consider 72 hours for complete clearance in elderly patients or those with renal dysfunction 2
- Do not bridge with heparin during this interruption period, as bridging is not generally required and heparin will also interfere with testing 3
Risk-Benefit Assessment
The decision to interrupt apixaban for testing must weigh the thrombotic risk against the diagnostic benefit, as premature discontinuation significantly increases stroke and thromboembolism risk. 3
- For patients with recent acute thrombosis (within 3 months), strongly consider performing only the tests that can be done on therapy 1
- For patients with high CHA₂DS₂-VASc scores (≥2) or recent VTE, the risk of interruption may outweigh the benefit of complete testing 2
- Protein C, protein S, and antithrombin III testing can be deferred until after the acute treatment phase (6+ months) when anticoagulation may be stopped or transitioned 3
Laboratory Monitoring Pitfalls
Standard Coagulation Tests Are Unreliable
- PT and aPTT are insensitive to apixaban levels - a normal PT/aPTT does NOT exclude therapeutic or supratherapeutic apixaban levels 4
- A prolonged PT suggests clinically important apixaban levels, but normal values are not reassuring 4
- If quantitation of apixaban is needed, use anti-Factor Xa assay calibrated specifically for apixaban 4
Practical Algorithm
For patients requiring hypercoagulable workup on apixaban:
Immediately obtain: Factor V Leiden, Prothrombin G20210A, antiphospholipid antibodies, platelet count 1
Assess thrombotic risk:
If interrupting apixaban for testing:
Special Populations
Renal Impairment
- Apixaban clearance is prolonged in renal dysfunction (half-life up to 17 hours) 2
- Severe renal impairment (CrCl <15 mL/min) is a relative contraindication to apixaban 5
- Allow 72 hours for drug clearance before testing in patients with CrCl <30 mL/min 2