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Methodology: Chromogenic Measurement of Factor Xa Inactivation
Edit Date: 3/7/2007
Performed: Daily
Released: 24 hours
CPT Code: 85520
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. Draw 3-4 hours after LMW heparin dose.
Handling: Refrigerate and keep capped in original tube if specimen will be received at the laboratory within 6 hours. If not, centrifuge to produce platelet-poor plasma (at least 1700 X G for 15 minutes) and transfer the top 2/3 of the plasma with a plastic pipette into a plastic vial, and freeze quickly. Label with patient name, test, and ‘plasma.’ If multiple tests are ordered, freeze a separate aliquot for each test. Send to labortory within one month.
Stability: Specimens stable 2 hours at ambient temperature, 8 hours refrigerated, or 1 month frozen.
Standard Volume: 5 mL whole blood or 2 mL plasma.
Minimum Volume: 1.8 mL whole blood or 0.5 mL plasma.
Transport: Original tube refrigerated if received in laboratory within 6 hours of collection, or plasma frozen on dry ice in a Styrofoam container.
Rejection Criteria: Serum; visible fibrin; moderate to marked hemolysis; specimen age.

Therapeutic Range:
0.35-0.70 U/mL

PeaceHealth Laboratories