Test Name: PROTEIN S ANTIGEN (FREE)
Test Code: 2188689
Alias: LAB492
CPT Code(s): 85306  
Preferred Specimen:

2.0 mL plasma
Container: 1 - full Sodium Citrate (blue) tube
Alternate Container: None
Minimum Volume: 1 - full Sodium Citrate (blue) tube
Collection Instructions:

Mix the tubes gently by inverting 5-10 times immediately after filling. Centrifuge for 15 minutes within 1 hour of collection.  Using a plastic pipette, remove plasma taking care to avoid the WBC/platelet buffy layer and transfer plasma into a properly labeled transfer tube. Centrifuge the transferred plasma a second time and transfer platelet poor plasma into a new properly labeled transfer tube. Label tube as "platelet poor".  Freeze immediately.

*Send both the transfer tube and the original tubes to the lab.
Transport Temperature:

Plasma:  Frozen
Original tubes:  Room Temperature
Stability: Frozen: 14 days
Rejection Criteria:

Refrigerated specimens

Room Temperature specimens

Partially thawed specimens
Schedule:

Turnaround time: 1-5 days
Method: Latex ligand immunoassay
Performing Lab: Northwestern Memorial Hospital
Clinical Significance: Protein S is a vitamin K-dependent cofactor for the anticoagulant and the profibrinolytic effects of activated Protein C. Two forms of Protein S are present in plasma: free Protein S (40%) and Protein S linked to the complement C4b-binding protein (C4BP) (60%). Only free Protein S has functional cofactor activity. Protein S deficiency may be hereditary or acquired. Acquired deficiency may be observed during pregnancy, oral anticoagulant therapy, oral contraceptive use, in liver disease, in newborn infants as well as in other clinical conditions. Deficiency of Protein S has been associated with a high risk of developing venous thromboembolism especially in young people.
Reference Ranges: Refer to patient report.

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The CPT codes included in this publication are in accordance with Current Procedural Terminology, a publication of the American Medical Association. CPT codes are provided here for the convenience of our clients; however, correct coding often varies from one carrier to another, and HealthLab may bill specific carriers using codes other than those shown. Clients who bill for services should verify the code(s) with the applicable payor to confirm that their use is appropriate in each case.
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