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26125 Protein C Antigen, No Coumadin (PCAG)

Protein C Antigen, No Coumadin (PCAG)
Test Code: PCAGSO
Synonyms/Keywords

​Protein C Immunologic

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)

Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​No ​Platelet-poor plasma ​Citrated Blue Top Tube (BTT) ​ ​1 mL ​0.5 mL ​
Collection Processing Instructions
​Special Note: Patient must be off of Coumadin for three weeks to order this test as Coumadin will lower Protein C Antigen level. If on Coumadin, order PROT-CM.
Fasting Preferred
 
1. Spin down, remove plasma, and spin plasma again.
2. Freeze specimen immediately (no longer than 4 hours after collection) at < or =-40 degrees C, if possible (freezing at -20 degrees C acceptable).
3. Submit specimen in a plastic vial.
 
 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.
Specimen Stability Information
Specimen Type Temperature Time
​Plasma Na Cit ​Frozen 2 Years
Rejection Criteria
Gross hemolysis
​Gross lipemia
Interference

Not useful for predicting a thrombotic event.

Performing Laboratory Information
 
Performing Location Day(s) Test Performed Report Available Methodology/Instrumentation
​Mayo Clinic Laboratories ​Monday through Friday3 -7 days ​Enzyme-Linked Immunosorbent Assay (ELISA)
Reference Lab
Mayo Clinic Laboratories
Test Information

Physiology:

Protein C is a vitamin K-dependent anticoagulant proenzyme. It is synthesized in the liver and circulates in the plasma. The biological half-life of plasma protein C is approximately 6 to 10 hours, similar to the relatively short half-life of coagulation factor VII.

Protein C is activated by thrombin, in the presence of an endothelial cell cofactor (thrombomodulin), to for​m the active enzyme, activated protein C (APC). APC functions as an anticoagulant by proteolytically inactivating the activated forms of coagulation factors V and VIII (factors Va and VIIIa). APC also enhances fibrinolysis by inactivating plasminogen activator inhibitor (PAI-1).

Expression of the anticoagulant activity of APC is enhanced by a cofactor, protein S, another vitamin K-dependent plasma protein.

Pathophysiology:

Congenital homozygous protein C deficiency results in a severe thrombotic diathesis, evident in the neonatal period and resembling purpura fulminans. Congenital heterozygous protein C deficiency may predispose to thrombotic events, primarily venous thromboembolism. Arterial thrombosis (stroke, myocardial infarction, etc) may occur. Some individuals with hereditary heterozygous protein C deficiency may have no personal or family history of thrombosis and may or may not be at increased risk.

The 2 types of hereditary heterozygous protein C deficiencies that are recognized are:

-Type I (concordantly decreased protein C function and antigen)

-Type II (decreased protein C function with normal antigen)

Acquired deficiency of protein C may occur in association with:

-Vitamin K deficiency

-Oral anticoagulation with Coumadin compounds

-Liver disease

-Intravascular coagulation and fibrinolysis/disseminated intravascular coagulation (ICF/DIC)

Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​Adults: 70%-150%
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 on Mayo's website.
Interpretation

Values <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.

Clinical significance of increased protein C is unknown.

Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​85302 ​ ​1 ​ ​
Synonyms/Keywords

​Protein C Immunologic

Ordering Applications
Ordering Application Description
​Cerner ​Protein C Antigen, P ​(PCAG)
​COM ​Protein C Antigen, Plasma (PCAG)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​No ​Platelet-poor plasma ​Citrated Blue Top Tube (BTT) ​ ​1 mL ​0.5 mL ​
Collection Processing
​Special Note: Patient must be off of Coumadin for three weeks to order this test as Coumadin will lower Protein C Antigen level. If on Coumadin, order PROT-CM.
Fasting Preferred
 
1. Spin down, remove plasma, and spin plasma again.
2. Freeze specimen immediately (no longer than 4 hours after collection) at < or =-40 degrees C, if possible (freezing at -20 degrees C acceptable).
3. Submit specimen in a plastic vial.
 
 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.
Specimen Stability Information
Specimen Type Temperature Time
​Plasma Na Cit ​Frozen 2 Years
Rejection Criteria
Gross hemolysis
​Gross lipemia
Interference

Not useful for predicting a thrombotic event.

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)

Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​Adults: 70%-150%
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 on Mayo's website.
Interpretation

Values <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.

Clinical significance of increased protein C is unknown.

For more information visit:
Performing Laboratory Information
 
Performing Location Day(s) Test Performed Report Available Methodology/Instrumentation
​Mayo Clinic Laboratories ​Monday through Friday3 -7 days ​Enzyme-Linked Immunosorbent Assay (ELISA)
Reference Lab
Mayo Clinic Laboratories
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​85302 ​ ​1 ​ ​
For most current information refer to the Marshfield Laboratory online reference manual.