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|27040:HEXAGONAL PHOSPHOLIPID NEUTRALIZATION TEST|
|Alias Names:||STACLOT / PNP / Platelet Neutralization Procedure|
|Methodology:||Mechanical Clot Detection|
|Specimen Collection Details|
|Collection:||One 4.5 mL light blue top tube (sodium citrate). Collect by careful venipuncture to avoid tissue fluid contamination or hemolysis. Do not use needles smaller than 23 gauge. Fill tube to maximum draw (at least 90% full). Mix by gentle inversion.|
|Handling:||Due to short stability, specimen must either be sent STAT to reach the laboratory within 4 hours, or sent frozen. For STAT, refrigerate and keep capped in original tube. Call for STAT pick-up. For standard transport, centrifuge to produce platelet-poor plasma (at least 1700 X G for 15 minutes) and using a plastic pipette, transfer the top 2/3 of the plasma into a plastic vial. Label with patient name, I.D. number, test, and “citrated plasma.” Freeze immediately. Send to the laboratory within 7 days. If multiple tests are ordered, freeze a separate aliquot for this test. NOTE: It is essential that plasma be truly “platelet poor” prior to freezing in order to prevent neutralization of lupus anticoagulants by platelet phospholipids. It is advisable to periodically check the platelet count of “platelet poor plasma” in your lab to assure that the count is consistently below 10,000/cumm. If not, centrifuge time and/or speed should be increased.|
|Stability:||4 hours ambient or refrigerated, or 7 days frozen.|
|Standard Volume:||4.5 mL whole blood or 2 mL plasma.|
|Minimum Volume:||1.8 mL whole blood or 1 mL plasma.|
|Transport:||Original tube refrigerated if received in laboratory within 4 hours of collection; plasma frozen on dry ice in Syrofoam container.|
|Comments:||See also: Coagulation Study, Anti-Phospholipid Panel (25620), Coagulation Study, Lupus Inhibitor Panel (25610), and Coagulation Study, Prolonged Activated Partial Thromboplastin Time (APTT) Evaluation (25670).
The Hexagonal Phospholipid Neutralization is a confirmatory test for lupus anticoagulants. A modified APTT is performed on patient plasma with and without added phospholipid. If the addition of phospholipid produces a significant correction in the APTT result, a lupus inhibitor is identified.
|Rejection Criteria:||Visible fibrin; moderate to marked hemolysis; specimen received in laboratory beyond stated stability.|
|<8.1-second phospholipid-dependent correction of the clotting time. Interpretive Data: A confirmatory test for lupus anticoagulants.|