Protein S Antigen, Free, Plasma
Use
Protein S is a vitamin K-dependent glycoprotein that works as part of the natural anticoagulant system. It acts as a cofactor to activated protein C (APC) in the inactivation of procoagulant factors Va and VIIIa. Approximately 40% of total plasma protein S circulates as free protein S, which has anticoagulant function. Deficiency can lead to increased risk of venous thrombosis and may also cause complications in pregnancy such as recurrent miscarriage and preeclampsia.
Special Instructions
Patient must not be receiving heparin or Coumadin. Coumadin should be noted as it will lower protein S levels. Each coagulation assay requested should have its own vial.
Limitations
Free protein S antigen results can be affected by various factors including heparin, hemoglobin, bilirubin, triglycerides, platelets, rheumatoid factor, and Factor V Leiden mutation. It is critical that specimens are double-centrifuged to avoid spurious results from platelet contamination.
New York Approved
Methodology
Immunoassay (Latex Immunoassay)
Biomarkers
LOINC Codes
- 27821-8
- 27821-8
Result Turnaround Time
1-4 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL in 2 plastic vials each containing 0.5 mL
Minimum Volume
0.5 mL
Container
Light-blue top (3.2% sodium citrate)
Collection Instructions
Centrifuge, transfer plasma into a plastic vial, and centrifuge again. Aliquot plasma into separate vials, leaving 0.25 mL in the bottom. Freeze at -20°C or ideally -40°C or below. Send in the same shipping container.
Patient Preparation
Patient must not be receiving heparin or Coumadin. Coumadin will lower protein S.
Storage Instructions
Freeze immediately. Stability at frozen state for 14 days.
Causes for Rejection
Gross hemolysis, gross lipemia, gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |