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Test Code PCAG Protein C Antigen, Plasma


Ordering Guidance


Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, consider ordering AATHR / Thrombophilia Profile, Plasma and Whole Blood.

 

Testing of protein C functional activity (CFX / Protein C Activity, Plasma) is recommended for initial laboratory evaluation of patients suspected of having congenital protein C deficiency (personal or family history of thrombotic diathesis).



Necessary Information


If the patient is being treated with Coumadin (warfarin), this should be noted as Coumadin will lower protein C.



Specimen Required


Specimen Type: Platelet-poor plasma

Patient Preparation: Fasting preferred

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial (polypropylene preferred)

Specimen Volume: 1 mL

Specimen Stability Information: Frozen 2 years

Collection Instructions:

1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.

2. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

3. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or ideally, at or below -40° C.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.


Forms

If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.

Useful For

Differentiating congenital type I protein C deficiency from type II deficiency

 

Evaluating the significance of decreased functional protein C, especially when decreased protein C activity might be congenital rather than acquired (eg, due to oral anticoagulant effect, vitamin K deficiency, liver disease, or intravascular coagulation and fibrinolysis/disseminated intravascular coagulation)

 

This test is not useful for predicting a thrombotic event.

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

Protein C Ag, P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject

Reference Values

Adults: 72%-160%

Normal, full-term newborn infants or healthy premature infants may have decreased levels of protein C antigen (15%-50%), which may not reach adult levels until later in childhood or early adolescence.*

*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing.

Interpretation

Values less than 70% to 75% may represent a congenital deficiency state, if acquired deficiencies can be excluded.

 

Protein C antigen and activities generally are undetectable in individuals with severe, homozygous protein C deficiency.

 

Acquired protein C deficiency is of uncertain clinical hemostatic significance.

 

The clinical significance of increased protein C is unknown.

Day(s) Performed

Monday through Friday

Report Available

3 to 7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

85302

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PCAG Protein C Ag, P 27820-0

 

Result ID Test Result Name Result LOINC Value
9127 Protein C Ag, P 27820-0