Protein S Antigen, Plasma
Use
This test is useful for the investigation of patients with a history of thrombosis. Protein S is a vitamin K-dependent glycoprotein critical for anticoagulation, acting as a cofactor to activated protein C (APC) and assisting in the proteolytic inactivation of procoagulant factors Va and VIIIa. Free protein S circulates in plasma and is vital for anticoagulant function. Congenital Protein S deficiency, an autosomal dominant disorder, significantly increases the risk of venous thrombosis. Additionally, the deficiency can lead to recurrent miscarriage and other pregnancy complications.
Special Instructions
It is important to use double-centrifuged specimens to avoid platelet contamination, which can cause spurious results. For non-electronic orders, use the Coagulation Test Request Form T753 with the specimen. Note that Coumadin may lower protein S levels and if the patient is being treated with Coumadin, it should be noted.
Limitations
The test results can be impacted by heparin (above 4 U/mL), high levels of hemoglobin, bilirubin, rheumatoid factor, or lipemic specimens. These factors can lead to inaccuracies such as overestimation or underestimation of protein S levels. The presence of specific antibodies may also lead to discrepancies in results.
New York Approved
Methodology
Immunoassay (Latex Immunoassay (LIA))
Biomarkers
LOINC Codes
- 87557-5
- 27821-8
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
Plastic vials
Collection Instructions
Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again. Aliquot 0.5 mL of plasma into two plastic vials, leaving 0.25 mL in the bottom of centrifuged vial. Freeze plasma immediately at -20 degrees C or ideally at -40 degrees C or below. Send specimens in the same shipping container.
Patient Preparation
Patient must not be receiving heparin or Coumadin. If the patient is being treated with Coumadin, this should be noted.
Causes for Rejection
Gross hemolysis, gross lipemia, and gross icterus.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |