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| Test Description |
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Test Name
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Lupus Anticoagulant |
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Synonym(s)
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Description
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Lupus Anticoagulants are antibodies directed against phospholipid-protein complex, which prolong the clotting times of phospholipid dependent assays. The Lupus Anticoagulant screen includes a Dilute Russell's Viper Venom Time (DRVVT) using dilute venom and dilute phospholipid to increase sensitivity. If it is abnormal, a confirmatory DRVVT is performed using a reagent with extra phospholipid which shortens the clotting time of a sample positive for the Lupus Anticoagulant. Panel includes PTT-LA with refelx to Hexagonal PL Neutralization Procedure. The PTT- LA is based on the measurement of plasma recalcification time of platelet substitute and activator. The presence of antiphospholipid antibodies prolongs the clotting time. If the DRVVT is negative, the Hexagonal Phospholipid Neutralization Test should be performed if there is a strong clinical suspicion. See Hexagonal Phospholipid Neutralization Test. |
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Methodology
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APTT based for PTT-LA and clotting for DRVVT |
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Performed
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Wednesday, Friday |
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Turnaround Time
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1-3 days |
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Specimen Requirements
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3 mL platelet-poor citrated plasma (light blue 3.2% sodium citrate tube). Freeze plasma within 4 hours of collection in 1 mL aliquots.
Transport frozen.
Minimum volume 2 mL.
Coagulation Drawing Instructions:
- When drawing coagulation tests, always draw a “pilot” tube (7-10 mL plain red top tube, completely filled). This removes tissue fluid contamination, discard pilot tube.
- Draw blood in a light blue (3.2% sodium citrate) top tube. Fill tubes as far as vacuum will fill and mix gently. Ratio of anticoagulant and blood must be maintained. Avoid slow flowing draws and traumatic venipunctures.
- Spin vacutainer – remove plasma avoiding platelet/buffy layer – spin plasma again – remove top portion of plasma and place 1 mL of PLATELET-POOR PLASMA in plastic tube. (Glass tube unacceptable)
- Double-centrifugation is critical for accurate results as platelet contamination may cause erroneous results.
- Plasma must be frozen within 4 hours of collection.
- CRITICAL WARNING: Specimen must remain frozen until testing.Submit separate aliquots when multiple tests are ordered on same patient specimen.
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Rejection Criteria
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Plasma hemolyzed, thawed or contaminated with heparin. |
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CPT Code(s)
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PTT-LA – 85730, dRVTT Screen – 85613, if dRVVT is positive then dRVVT confirmation – 85612 and interpretation – 85390.
If PTT-LA pos and dRVVT confirmation neg then Hexagonal neutralization test – 85597, 85730 |
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Reference Range
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See interpretive report. |
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Contact Information
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Hemostasis Lab: 214-645-5067
Customer Service: 214-645-7057, Toll Free 877-887-8136 |
Last Modified: 01/05/2011 |
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