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)
Enzyme-Linked Immunosorbent Assay (ELISA)
Protein C Immunologic
Plasma Na Cit
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).
If the patient is being treated with Coumadin, this should be noted as Coumadin will lower protein C.
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 degrees C or, ideally < or =-40 degrees 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.
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.
0.5 mL
Gross hemolysis | Reject |
Gross lipemia | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Plasma Na Cit | Frozen |
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)
Physiology
Protein C is a vitamin K-dependent anticoagulant proenzyme.
Protein C is activated by thrombin, in the presence of an endothelial cell
Pathophysiology
Congenital homozygous protein C deficiency results in a severe
Congenital heterozygous protein C deficiency may predispose to
The 2 types of hereditary heterozygous protein C deficiencies that are
-Type I (concordantly decreased protein C function and
-Type II (decreased protein C function with normal antigen)
Acquired deficiency of protein C may occur in association with
-Vitamin K deficiency
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.
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.
No significant cautionary statements
1. Mannucci PM, Owen WG: Basic and clinical aspects of proteins C and S. In: Bloom AL, Thomas DP, eds. Haemostasis and Thrombosis. 2nd ed. Edinburgh, Churchill Livingstone; 1987:452-464
2. Marlar RA, Mastovich S: Hereditary protein C deficiency: a review of the genetics, clinical presentation, diagnosis and treatment. Blood Coagul Fibrinolysis. 1990 Aug;1(3):319-330
3. Marlar RA, Montgomery RR, Broekmans AW: Diagnosis and treatment of homozygous protein C deficiency. Report of the Working Party on Homozygous Protein C Deficiency of the Subcommittee on Protein C and Protein S, International Committee on Thrombosis and Haemeostasis. J Pediatr. 1989 Apr;114(4 Pt 1):528-534
4. Miletrich J, Sherman L, Broze G Jr: Absence of thrombosis in subjects with heterozygous protein C deficiency. N Engl J Med. 1987 Oct 15;317(16):991-996
5. Cooper PC, Pavlova A, Moore GW, Hickey KP, Marlar RA: Recommendations for clinical laboratory testing for protein C deficiency, for the subcommittee on plasma coagulation inhibitors of the ISTH. J Thromb Haemost. 2020 Feb;18(2):271-277
Protein C antigen is quantitated by enzyme-linked immunoassay (ELISA) using monospecific antibody. The assay is performed using the REAADS PCAg kit on a Janus G3 integrated system, which includes a BioTek microplate reader.(Package insert: REAADS Protein C Antigen Test Kit. Corgenix, Inc; 08/2015)
Monday through Friday
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.
85302
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
PCAG | Protein C Ag, P | 27820-0 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
9127 | Protein C Ag, P | 27820-0 |
Change Type | Effective Date |
---|---|
Test Changes - Reference Value | 2022-08-04 |
Test Status - Test Down | 2021-05-05 |