Protein C Antigen

Test Code

PTCAG

Alias/See Also

LAB8344

CPT Codes
<p>85302</p>

Preferred Specimen

Specimen Type: Platelet-poor plasma

Collection Container/Type: Light blue top (citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

Completely fill tube. Underfilled tubes are unacceptable
Centrifuge, remove plasma, and centrifuge plasma again.
Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

For complete instructions, see Platelet Poor Plasma Instructions.

Minimum Volume

0.5 mL

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.

Transport Container

Plastic vial

Transport Temperature

Frozen

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

Methodology

Enzyme Immunoassay (EIA)

Setup Schedule

Set up: Mon-Fri; Report available: 1-4 days

Report Available

1-4 days

Limitations

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

70-140 % normal

Clinical Significance

Aids in characterization of congenital 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: vitamin K antagonists (eg. warfarin) will decrease PC antigen levels. PC antigen testing is not impacted by other anticoagulants (heparins, and target specific anticoagulants such as Dabigatran, Argatroban, Rivaroxaban, Apixaban, Edoxaban).

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

Last Updated: February 17, 2023

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.