Protein C and S Activity with Reflex to Protein C and/or S Antigen
Also known as: PC Activity, PC Antigen, Protein S Functional, PS Activity, PS Antigen
Use
Aids in evaluation of protein C (PC) and protein S (PS) deficiencies, which are associated with increased thrombotic risk. Deficiencies may be congenital or acquired, and acquired causes include vitamin K deficiency, liver disease, malignancy, DIC, surgery, trauma, or neonatal hepatic immaturity. Protein S deficiency may also be physiologic in pregnancy.
Special Instructions
Submit a separate, frozen vial for each special coagulation assay ordered. Draw blood in a light blue-top tube containing 3.2% sodium citrate, mix gently by inverting 3–4 times. Centrifuge 15 minutes at 1500 g within one hour of collection, then remove plasma carefully, avoiding buffy coat, and re-centrifuge to obtain platelet‑poor plasma. Freeze immediately and transport on dry ice or frozen. Room temperature and refrigerated specimens are unacceptable; frozen stability up to 14 days.
Limitations
Anticoagulant interference: Therapeutic warfarin may decrease activity; heparin (UFH or LMWH) may have no effect or falsely increase activity at higher levels; dabigatran or argatroban may falsely increase activity; factor Xa inhibitors (rivaroxaban, apixaban, edoxaban) may falsely increase activity.
Methodology
Other
Biomarkers
Result Turnaround Time
Not provided.
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
Draw two light blue-top (sodium citrate) tubes, desired specimen volume: 4 mL (2 mL per aliquot)
Minimum Volume
Not provided
Container
Light Blue Top (Sodium Citrate)
Collection Instructions
Collect two sodium citrate tubes; mix by inverting 3‑4 times. Centrifuge 15 min at 1500 g within 1 h, transfer platelet‑poor plasma into two separate clear aliquot tubes (2 mL each), freeze immediately.
Storage Instructions
Transport frozen (on dry ice); room temperature and refrigerated specimens unacceptable.
Causes for Rejection
Hemolysis; room temperature or refrigerated specimens
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |