Partial Thromboplastin Time, Activated (aPTT)
One full 3.2% unopened sodium citrate (light blue-top) tube
Ratio of blood to citrate is critical. Submit difficult draws in a pediatric (light blue-top) tube. 0.5 mL frozen plasma.
1 mL frozen plasma: for Heparinized patients or if testing will be delayed longer than 6 hours, centrifuge specimen within 1 hour of collection at 2500-3500 rpm. Transfer plasma to a plastic screw-cap vial and freeze at -20¡C immediately. Ship with dry ice.
Correct ratio of blood to citrate is critical. Do not overfill or under fill collection tube. Mix by inversion 4 times. For non-heparinized patients, maintain specimen at room temperature. Do not uncap. Stable 24 hours at room temperature.
3.2% sodium citrate (light blue-top) tube
Transport Temperature Name:
Specimen Stability Components:
- Room Temperature: Unopened light blue-top tube Room temperature: 24 hours Frozen: Unacceptable Separated platelet poor plasma Frozen -20¡C: 7 days
Mechanical Clot Detection
Reagent Lot Specific (30-40 sec)
Gross hemolysis ¥ Gross lipemia ¥ Improper blood to citrate ratio ¥ Clotted ¥ High hematocrits