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Protein C Activity and Antigen
Test Code8757
CPT Codes
85302, 85303
Preferred Specimen
2 mL frozen plasma (1 mL in two separate tubes) collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.5 mL (x2)
Instructions
Please 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. Using a plastic pipette, remove plasma, taking care to avoid the
WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor
plasma into a new plastic vial(s). Freeze immediately and transport on dry ice.
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. Using a plastic pipette, remove plasma, taking care to avoid the
WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor
plasma into a new plastic vial(s). Freeze immediately and transport on dry ice.
Transport Temperature
Frozen
Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 14 days
Refrigerated: Unacceptable
Frozen: 14 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis
Methodology
Clotting Assay • Immunoassay (IA)
Setup Schedule
See individual assays
Limitations
Protein C, Activity: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: decrease; Heparin (UFH or LMWH): UFH-no effect, LMWH-may falsely increase at higher levels; Dabigatran or Argatroban (Thrombin Inhibitors): may falsely increase; Rivaroxaban or Apixaban (Factor Xa Inhibitors): may falsely increase.
Protein C, Antigen: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: no effect to decrease; Heparin (UFH or LMWH): no effect; Dabigatran or Argatroban (Thrombin Inhibitors): no effect; Rivaroxaban or Apixaban (Factor Xa Inhibitors): no effect.
Protein C, Antigen: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: no effect to decrease; Heparin (UFH or LMWH): no effect; Dabigatran or Argatroban (Thrombin Inhibitors): no effect; Rivaroxaban or Apixaban (Factor Xa Inhibitors): no effect.
Clinical Significance
Aids in characterization of protein C deficiency. Type I deficiency is characterized by reduction in activity (functional) and antigen levels. With type II deficiency (dysfunctional protein), antigen levels may be normal and activity levels are decreased. Acquired deficiencies may occur with vitamin K antagonists/deficiency, liver disease, malignancy, consumptive DIC, surgery, trauma, and hepatic immaturity of the newborn. Drug therapy with L-asparaginase or fluorouracil can also reduce Protein C antigen levels.
Anticoagulant interference: Expected impact by therapeutic levels (potential interference depends upondrug concentration): Vitamin K Antagonists (eg. coumadin): decrease; Heparin (UFH or LMWH): no effect to falsely increased activity levels at higher levels; Dabigatran or Argatroban (Direct Thrombin Inhibitors): may falsely increase activity; Rivaroxaban, Apixaban, Edoxaban (Factor Xa Inhibitors): may falsely increase activity.
Anticoagulant interference: Expected impact by therapeutic levels (potential interference depends upondrug concentration): Vitamin K Antagonists (eg. coumadin): decrease; Heparin (UFH or LMWH): no effect to falsely increased activity levels at higher levels; Dabigatran or Argatroban (Direct Thrombin Inhibitors): may falsely increase activity; Rivaroxaban, Apixaban, Edoxaban (Factor Xa Inhibitors): may falsely increase activity.
