Synonyms
PF4
Expected Turnaround Time
2 - 7 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Plasma
Volume
1 mL
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
CTAD collection tube required. Contact client services to request the CTAD special collection tube.
Collection
The reliability of platelet marker assay results is dependent on the quality of the sample collection. The CTAD tube is a mixture of buffered sodium citrate, theophylline, adenosine, and dipyridamole. It is used to minimize in vitro platelet activation. Kits can be ordered through the PeopleSoft System (LabCorp N° 73812). 1. Break the vacuum of the tube containing the special anticoagulant by removing the stopper before sample collection. 2. Using a loosely tied tourniquet (only for locating the vein), perform the venipuncture using preferably a 19-gauge butterfly needle set, but use a needle no smaller than a 21-gauge. 3. Start the venipuncture, removing the tourniquet as soon as the first drops of blood appear in the butterfly tubing. Using a two-syringe draw technique, the sample is collected by first drawing and discarding the first 2 mL of blood either in a syringe or a red-top tube. Collect the next 5 mL of blood into a syringe. 4. After completing the blood draw, discard the butterfly tubing and place in a sharps container. Using the syringe, gently express 4.5 mL of sample collected down the side of the special collection CTAD tube. Too vigorous transfer into the CTAD tube may activate the platelets. Cap the tube and invert gently three times. 5. Within one hour, centrifuge the sample at 2500xg for 20 minutes. 6. When centrifugation is complete, collect one-third the volume of the plasma supernatant from the middle region of the plasma portion of the CTAD sample using a plastic pipette, and transfer it into a polypropylene transport tube. Take care not to aspirate from neither near the top surface nor the red cell layer at the bottom, as platelets will enter the specimen. 7. Centrifuge the aliquot a second time at 2500xg for 20 minutes to obtain platelet-poor plasma. Collect one-third of the supernatant as above. 8. Follow specimen identification and labeling procedures as outlined. The transport tube should be clearly marked as "CTAD plasma."
Storage Instructions
Ship frozen on dry ice.
Test Details
Methodology
Enzyme-linked immunoassay (ELISA)
Reference Interval
Range (IU/mL) <75