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HelpTest Code LAB8935 Protein C Activity, Plasma
Additional Codes
CFX
Useful For
As an initial test for evaluating patients suspected of having congenital protein C deficiency, including those with personal or family histories of thrombotic events
Detecting and confirming congenital type I and type II protein C deficiencies
Detecting and confirming congenital homozygous protein C deficiency
Identifying decreased functional protein C of acquired origin (eg, due to oral anticoagulant effect, vitamin K deficiency, liver disease, intravascular coagulation and fibrinolysis/disseminated intravascular coagulation)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Plasma Na CitOrdering 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.
Necessary Information
1. If the patient is being treated with Coumadin, this should be noted. Coumadin will lower protein C.
2. Heparin (unfractionated or low molecular weight) 2 U/mL or more may interfere with this assay.
Specimen Required
Specimen Type: Platelet-poor plasma
Patient Preparation: Fasting
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
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 -40° C or below.
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.
On-campus collections: Tube to 99 or deliver to University Extension Hospital Room EH318. Submission Container/Tube: Plastic vial, Frozen
Off-campus collections: Centrifuge and aliquot within 2 hours. Specimen to be stored/transported at Frozen temp.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Special Instructions
Day(s) Performed
Monday through Friday
CPT Code Information
85303
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CFX | Protein C Activity, P | 27818-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CFX | Protein C Activity, P | 27818-4 |
Interpretation
Values below 60% to 70% may represent a congenital deficiency state, if acquired deficiencies can be excluded.
Protein C activity (and antigen) is generally undetectable in individuals with severe, homozygous protein C deficiency.
Oral anticoagulant therapy (warfarin, Coumadin) decreases protein C activity, compromising the ability to distinguish between congenital and acquired protein C deficiency. Concomitant measurement of the activity of coagulation factor VII (or factor X) may aid in differentiating congenital deficiency state from acquired protein C deficiency due to oral anticoagulant effect, but the ratio of the activities of protein C:factor VII (or factor X) has not been demonstrated to provide certainty about this distinction.
The clinical significance of acquired protein C deficiency and of increased protein C is unknown.
Method Description
This Protein C activity assay is performed using the HemosIL Protein C kit on the Instrumentation Laboratory ACL TOP. Protein C in plasma is activated by a specific enzyme (protein C activator) from copperhead snake venom (Agkistrodon contortrix contortrix). The amount of activated protein C is determined by the rate of hydrolysis of the chromogenic substrate, S-2366 (pyroGlu Pro-Arg-pNA-HCL). The pNA release is measured kinetically at 405 nm and is directly proportional to the protein C level in the plasma.(Package insert: HemosIL Protein C. Instrumentation Laboratory; 03/2016)
Report Available
1 to 3 daysSpecimen Retention Time
7 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Method Name
Chromogenic
Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.
Secondary ID
9339Reference Values
70-150%