Invert tube 5 to 10 times immediately after filling and transport to the lab at room temperature.
*NOTE: For patients on heparin, specimen must be centrifuged within 1 hour of collection and tested within 4 hours if kept at room temperature or refrigerated. To increase stability send frozen. Centrifuge the specimen for 15 minutes within 1 hour of collection. Using a plastic pipette, remove the plasma taking care to avoid the WBC/platelet buffy layer and transfer the plasma into a properly labeled transfer tube. Centrifuge the transferred plasma a second time and transfer platelet poor plasma into a new properly labeled transfer tube. Label tube as "platelet poor". Freeze immediately and transport to the lab frozen.
*Send both the transfer tube (frozen) and the original tube (room temp) to the lab.