Protein S Antigen, Free


Sunquest Code:PSF  
Epic Code:LAB492Epic Name:Protein S Antigen Free
Synonyms:Free Protein S
Methodology:Latex immunoassay/Immuno-turbidmetric assay
CPT Code:85306
Turnaround Time:Specimen is accepted and processed 24 hours/day, 7 days/week. Test is performed 2-3 times/week; results are reported within 3-5 days.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens



Collection Instructions

Specimen:Blood
Optimal Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Minimum\Peds Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tubes or clotted specimens.


Processing and Shipping

Specimen Processing:See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab Special Coagulation  (UMMC-East Bank)


Interpretive

Critical Range:Less than 20% (for 5 days and older).
Reference Range:

 

Protein S Free LIA

Newborn

33-67%

1 – 4 d

24-48%

5 – 29 d

36-64%

30 – 89 d

48-78%

90 d – 10 y

60-135%

11 y – adult, Male

70-148%

11 y – adult, Female

55-125%

 

 

Use:Protein S is a Vitamin K dependent plasma glycoprotein that serves as the cofactor for the anticoagulant function of activated Protein C inactivating activated Factors 5 and 8. Since it is Vitamin K dependent, it is decreased in warfarin therapy or Vitamin K deficiency. Protein S deficiency is a risk factor for thromboembolism. Severe deficiency may cause purpura fulminans. Protein S circulates in plasma in two forms: 40% is free Protein S, 60% is bound to C4B binding protein. Only the Free has cofactor activity for Protein C, therefore, it is the preferred method for measuring Protein S.


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