Specimen Requirements

Draw blood in a light blue-top (3.2% sodium citrate) tube(s), and send 4.5 mL of sodium citrate whole blood at room temperature.  If the specimen will not arrive to St. Luke's Laboratory within 24 hours of collection, Centrifuge the capped specimen tube, remove plasma, and spin plasma again to produce platelet poor plasma. Use a plastic transfer pipette; remove the plasma to a plastic tube without disturbing the buffy coat.  If testing is not completed within 24 hours, the plasma may be stored at ≤20⁰C or below for up to 14 days. 

Clotted or visibly hemolyzed specimens, specimens drawn in wrong tube, or tubes that have less than expected fill is not acceptable and will be rejected.
 

Note:  1. Mix 9 parts of freshly drawn blood with 1 part of 3.2% sodium citrate anticoagulant. Invert tube gently 3 to 4 times immediately after venipuncture to ensure proper mixing of blood and anticoagulant.

2. If blood is drawn through an indwelling catheter, flush line with 5 mL of saline. Discard first 5 mL of blood or 6 dead space volumes of catheter, or use for other laboratory tests.

3. If blood is drawn with a butterfly set, a waste tube must be drawn to eliminate dead space of tubing to ensure adequate blood is drawn into coagulation tube.

4. 3.2% sodium citrate concentration must be adjusted in patients who have hematocrit values >55%.

5. Plasma from a nonheparinized patient should be tested within 24 hours of draw (centrifuged or uncentrifuged), if stored in an unopened tube at room temperature. Plasma from a heparinized patient must be centrifuged within 1 hour of draw and tested within 4 hours. If there is a delay in testing greater than these limits, freeze specimen in plastic vial.