Test Code PROTS PROTEIN S ACTIVITY [LAB491]
Performing Laboratory
Pathology Laboratory
Laboratory Section:
Core Laboratory
Clinical Testing | Pathology Laboratory
Test Performance
Once per day Tuesday and Thursday, Dayshift Only (Specimen must be in lab prior to 10 am)
Methodology
Clot Based Method
Specimen Requirements
Container/Tube Type:
Light Blue (Citrate)
Collection Information:
Promptly after collection, spin down and place 1 mL of platelet-poor plasma in plastic vial. (Glass vial is not acceptable.) Freeze specimen immediately at ≤ -40° C, if possible.
Minimum Sample Volume:
0.5 mL
Unacceptable Conditions:
Hemolyzed or lipemic specimens.
Platelet Poor Plasma
Centrifuge Specimen
Recommended centrifuge speed is 1500 x G for at least 15 minutes. Be careful that the tubes are evenly balanced when placing them into the centrifuge. When the centrifuge stops, carefully remove and rack tubes. Be aware that an unbalanced centrifugation, speed too slow, or centrifugation for too short of a spin time may all lead to an increase number of cells in the plasma which could contribute to a clotted specimen or erroneous results.
Remove Plasma
To remove plasma, start from the top, gently draw specimen into pipette as you go further down tube. Leaving approximately 0.5mL of plasma will insure that you do not disturb the buffy coat and cell layer.
Second Spin
Plasma separated from cells goes back into the centrifuge for a second spin. Balance and centrifuge the tubes. Failure to perform a second spin will result in plasma containing too many platelets which interfere with some coagulation testing and is a contributing factor for a clotted specimen.
Transfer Plasma to Aliquot Tubes
Pipette plasma from second spin tube into labeled aliquot tubes without disturbing the bottom 0.5mL.
Specimen Storage
Promptly freeze specimens after processing.
Specimen Stability
Refrigerated Stability:
NOT Acceptable
Frozen Stability:
14 days
Ambient Stability:
NOT Acceptable
CPT Coding
85306
Alias
Functional Protein S
Protein S Activity, Plasma