🧪 What is the Lupus Anticoagulant Test?

Despite the name, Lupus Anticoagulants (LA) are autoantibodies associated not with bleeding, but with increased blood clotting.

• They are part of a group called antiphospholipid antibodies (aPL).
• LA antibodies interfere with phospholipid-dependent clotting tests in the lab (prolonging them), but increase the risk of thrombosis in the body.

❓ Why is the Test Done?

To:

• Investigate unexplained blood clots (DVT, PE, stroke)
• Diagnose Antiphospholipid Syndrome (APS)
• Evaluate recurrent miscarriages, particularly in the second or third trimester
• Help assess prolonged aPTT (activated partial thromboplastin time) with no bleeding tendency

🧬 Antiphospholipid Syndrome (APS)

Lupus anticoagulants are one of the criteria for APS diagnosis, along with:

• Anti-cardiolipin antibodies
• β2-glycoprotein I antibodies

🧪 How is the Test Performed?

It involves a series of coagulation tests, typically:

1. Screening test: aPTT, dRVVT (Dilute Russell Viper Venom Test), or LA-sensitive PTT
2. Mixing studies: rule out clotting factor deficiencies
3. Confirmatory tests: confirm phospholipid dependence

A diagnosis of LA requires persistent positivity at ≥12 weeks apart.

📊 Interpretation of Results

Important to repeat the test after 12 weeks to confirm persistent positivity.

🧠 Associated Conditions

🔄 Related / Follow-Up Tests

• Anti-cardiolipin antibodies (IgG/IgM)
• Anti-β2 glycoprotein I antibodies
• aPTT, PT/INR
• Thrombin Time
• Platelet count, D-dimer
• ANA (for lupus workup)

✅ Fasting Required?

⚠️ Precautions

• Avoid testing during acute thrombosis or anticoagulant therapy (e.g., heparin, warfarin, DOACs), as it may cause false positives or negatives.
• Inform the lab if the patient is on anticoagulants.

📝 Summary Table