Protein C Activity, Plasma
Use
This test is used as an initial investigation for evaluating patients suspected of having congenital protein C deficiency, such as those with a personal or family history of thrombotic episodes. It helps in detecting and confirming congenital type I and type II protein C deficiencies, including homozygous deficiency. Additionally, the test aids in identifying decreased functional protein C of acquired causes like oral anticoagulant effects, vitamin K deficiency, liver disease, and intravascular coagulation and fibrinolysis/disseminated intravascular coagulation.
Special Instructions
Testing for coagulation is intricate, often requiring multiple assays and correlation with clinical data. If the patient is under treatment with Coumadin, it should be noted as it lowers protein C levels. Interference from Heparin (unfractionated or low molecular weight) at concentrations of 2 U/mL or higher should be considered.
Limitations
Protein C activity measurements may be affected by the presence of Heparin (≥2 U/mL), Hemoglobin (>500 mg/dL), Bilirubin (>21 mg/dL), and Triglycerides (>890 mg/dL). Lipemia can also interfere with assay results. Samples should ideally be drawn in a fasting state to avoid erroneous outcomes. Furthermore, this chromogenic assay may not detect certain congenital protein C variants identifiable with clot-based functional assays.
New York Approved
Methodology
Chromogenic
Biomarkers
LOINC Codes
- 27818-4
- 27818-4
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Polypropylene plastic vial
Collection Instructions
Centrifuge, transfer plasma into a plastic vial, and centrifuge again. Aliquot plasma into a vial leaving 0.25 mL in the original tube. Freeze immediately at -20°C or, ideally, at -40°C or below.
Patient Preparation
Fasting for 8 hours is preferred but not required.
Causes for Rejection
Gross hemolysis, lipemia, or icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |