From the Guidelines
A thrombophilia evaluation should include a comprehensive set of tests, including antithrombin activity, protein C activity, protein S activity, factor V Leiden mutation, prothrombin G20210A mutation, lupus anticoagulant, anticardiolipin antibodies, anti-beta2 glycoprotein antibodies, homocysteine levels, and a complete blood count, as recommended by various studies 1.
Key Tests for Thrombophilia Evaluation
- Antithrombin activity
- Protein C activity
- Protein S activity
- Factor V Leiden mutation
- Prothrombin G20210A mutation
- Lupus anticoagulant
- Anticardiolipin antibodies
- Anti-beta2 glycoprotein antibodies
- Homocysteine levels
- Complete blood count Additionally, consider including activated protein C resistance, factor VIII levels, and JAK2 V617F mutation testing if there's suspicion of myeloproliferative disorders, as suggested by studies 1.
Considerations for Testing
- Timing is crucial: ideally perform testing at least 2-3 weeks after completing anticoagulation therapy and not during an acute thrombotic event, as results can be affected 1.
- For patients on warfarin, protein C and S testing should be delayed until at least 2 weeks after discontinuation.
- Consider clinical context when ordering these tests, as they're most valuable in patients with unprovoked thrombosis, thrombosis at unusual sites, recurrent events, or positive family history. The results help determine the underlying cause of thrombotic tendency, guide anticoagulation duration decisions, and inform family screening recommendations, as highlighted in studies 1.
From the Research
Thrombophilia Evaluation Workup
To evaluate thrombophilia, the following tests are recommended:
- Determination or measurement of factor V Leiden 2
- Factor II G20210A 2
- Antithrombin 2
- Protein C 2
- Protein S 2
- Antiphospholipid antibodies 2
- Hyperhomocysteinemia 2
Laboratory Testing Program
A combined clinical and laboratory approach should be taken into account when tailoring a laboratory testing program for each individual patient 2. This approach should consider the patient's history, family history, prevalence of defects, and accuracy of tests.
Test Interpretation
When interpreting test results, it is essential to consider pre-analytical, analytical, and post-analytical variables to minimize misinterpretation 3. Additionally, test results should be reported in a way that is clear and consistent, using standardized units such as international normalized ratio (INR) for prothrombin time (PT) results 4.
Clinical Indications
Thrombophilia testing should be undertaken when the test result is likely to influence management decisions, rather than universal screening in all patients with thrombosis 3. The clinical indications for thrombophilia testing have been covered elsewhere, and the focus should be on laboratory considerations in thrombophilia testing 3.
Common Questions on Laboratory Assessment and Management
Common questions on laboratory assessment and management of thrombophilia include what are the potential indications for thrombophilia testing, who should be tested, what tests should be requested, when should testing be performed, and how should the test results affect primary prevention, acute therapy, and secondary prophylaxis of thrombosis 5.