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.
Keep capped and refrigerate 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 top 2/3 of the plasma with a plastic pipette into a plastic vial. Freeze immediately. Label with patient name, test, and ‘citrated plasma.’ If multiple tests are ordered, freeze a separate aliquot for this test. Send to laboratory within one month.
2 hours ambient, 8 hours refrigerated, or 1 month frozen.
5 mL whole blood or 2 mL plasma.
1.8 mL whole blood or 0.5 mL plasma.
Original tube refrigerated if received in laboratory within 6 hours of collection, or plasma frozen on dry ice in a Styrofoam container.
Tinzaparin is sold as ‘Innohep’ (proprietary synonym).
Serum; visible fibrin; moderate to marked hemolysis; specimen age.