One 4.5 mL light blue top tube (sodium citrate). Collect by careful venipuncture to avoid tissue contamination or hemolysis. Do not use needles smaller than 23 gauge. Fill tube to maximum draw, at least 90% full. Mix by gentle inversion.
Refrigerate and keep capped in original tube if specimen will be received at laboratory within 4 hours. If not, centrifuge to produce platelet-poor plasma and transfer to a plastic tube. Freeze immediately. Label with patient name, test, and “plasma.” If multiple tests are ordered, freeze a separate aliquot for this test. Send to laboratory within one week.
One 4.5 mL light blue tube (sodium citrate) or 2 mL plasma
One 2.7 mL light blue tube (sodium citrate) or 0.5 mL plasma
Original tube refrigerated, or citrated plasma frozen on dry ice.
Patient must not be on heparin, which will interfere with clot-based factor assays.