Lupus Anticoagulant Evaluation with Reflex
Use
This evaluation screens for lupus anticoagulants using two coagulation pathway assays—PTT‑LA (intrinsic pathway) and dRVVT (common pathway). If a screening test is prolonged, it reflexively proceeds to a confirmatory test (Hexagonal Phase Confirm or dRVVT Confirm), and if still positive or prolonged, further reflex to mixing studies occurs. The detection of LA by either confirmatory assay supports a positive result.
Special Instructions
Specimen must be platelet‑poor plasma. Plasma should be frozen immediately and shipped on dry ice to prevent degradation. Whole blood at room temperature or refrigerated is unacceptable; frozen plasma is acceptable for up to 30 days. Reagent interference (e.g., warfarin, direct Xa or thrombin inhibitors) may cause indeterminate results; anticoagulants should be held (warfarin for 2 weeks, heparin for ≥24 hours) prior to testing.
Limitations
False‑positive or indeterminate results may occur in patients on anticoagulant therapy, notably warfarin, unfractionated heparin, low‑molecular‑weight heparin, and direct oral anticoagulants; holding these agents prior to testing is advised. A “weak” positive Hexagonal Phase Confirm indicates a result just above positivity cut‑off and reflects a laboratory finding only, not clinical severity. Testing during acute thrombosis or emergent situations is not recommended.
Methodology
Chromosomal / Cytogenetics
Biomarkers
Result Turnaround Time
Not provided.
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
Not provided
Minimum Volume
Not provided
Collection Instructions
Plasma must be platelet‑poor (<10,000/mcL), frozen immediately and shipped on dry ice. Whole blood at room temperature or refrigerated is unacceptable.
Storage Instructions
Frozen; whole blood not acceptable; plasma frozen acceptable up to 30 days.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 30 days |
Other tests from different labs that may be relevant