Lupus Anticoagulant (without DRVTT)

Key Alternatives to dRVVT

• Sensitive aPTT (aPTT-LA): Uses low phospholipid concentrations to detect LA, often as a first-line screen alongside or instead of dRVVT.
• Hexagonal Phase Phospholipid Neutralization (e.g., PTT-LA): A confirmatory test that uses hexagonal phase phospholipids to neutralize the LA, causing the prolonged aPTT to correct.
• Kaolin Clotting Time (KCT): An older, highly sensitive method often used when heparin interference is not an issue, though less specific than dRVVT.
• Taipan Snake Venom Time (TSVT) / Ecarin Time (ET): Useful in patients already taking anticoagulants (like heparin or DOACs) because these tests are less affected by them, while remaining sensitive to LA.

Important Considerations

• Confirmation Needed: A positive screening test (like aPTT-LA) must be confirmed by a neutralization procedure to confirm it is an inhibitor and not a factor deficiency.
• Anticoagulant Interference: If the patient is on anticoagulants (e.g., heparin, warfarin, DOACs), tests may show false-positives. It is recommended to test when therapy has ceased, if possible.
• Testing Limitations: Using only one assay can reduce detection sensitivity, so the ISTH recommends using at least two different methods (e.g., aPTT-LA + KCT) if dRVVT is not used.