Protein C, Activity and Antigen [8757X]

Test Code

CPT Codes
85302, 85303

Protein C Antigen; Protein C, Activity

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)

Please submit a separate, frozen vial for each coagulation assay. Do not thaw. Please see individual assays for specimen requirements.
Refer to Quest Diagnostics Nichols Institute Directory of Services under Specimen Collection section, Coagulation Testing, for further information on specimen processing.

Transport Container
Plastic screw-cap vial (x2)

Transport Temperature

Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen (-20°C): 14 days;
Frozen (-70°C): 1 year

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis

Clotting Assay • Immunoassay (IA)

Setup Schedule
Set up: Mon-Fri a.m.; Report available: Next day

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.

Reference Range
Protein C Activity 70-180 % normal
Protein C Antigen 70-140 % normal

Clinical Significance
Comprehensive test assesses the total level of protein and its functional activity in determining Protein C deficiency, which is strongly prothrombotic, and may require long-term anticoagulation therapy. In the presence of low Protein C Activity, Protein C Antigen helps to confirm and to classify Protein C Deficiency as Type I or Type II. Protein C is a highly thrombophilic protein.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.