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Protein S Antigen, Total and Free : 36457
Test CodePRTSFT or 36457
CPT Codes
85306, 85305
Includes
Protein S Anitgen Total and Protein S Antigen Total
Instructions
Draw blood in a light blue-top tube containing 3.2% sodium citrate, mix gently by inverting 3-4 times. Centrifuge 15 minutes at 1500 g within one hour of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial(s). Plasma must be free of platelets (<10,000/uL). Freeze immediately and transport on dry ice.
Transport Container
Preferred Specimen
2 mL frozen plasma collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
1 mL
2 mL frozen plasma collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
1 mL
Transport Temperature
Frozen.
Specimen Stability
Room temperature: Unacceptable; Refrigerated: Unacceptable; Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis, Received room temperature, Received refrigerated
Methodology
Immunoturbidimetric
Setup Schedule
Tuesday & Thursday
Report Available
1-6 days
Reference Range
Protein S Antigen, Total 70-140 % normal
Protein S Antigen, Free
Male 57-171 % normal
Female 50-147 % normal
Clinical Significance
Protein S Antigen, Total and Free - Antigen testing is appropriate when a functional activity deficiency is present. If low, Total Protein S Antigen assesses the Protein S deficiency as either Type I or III (IIa). Type II (IIb) Protein S deficiency has normal concentrations of Total and Free Protein S Antigen.
Total Protein S is comprised of Free Protein S and Protein S bound to a complement protein, C4B-BP. The relative proportions of the free and bound forms are 40% and 60%, respectively. It is the free form of Protein S that serves as the cofactor for activated protein C (APC). The APC/free PS complex serves to down regulate thrombin generation via proteolytic inactivation of Factors Va and VIIIa. Therefore, a deficiency in Protein S increases an individual’s risk for thrombosis since the normal mechanism of thrombin inhibition is decreased. Deficiencies of Protein S may be inherited or acquired. Acquired deficiencies of Protein S result from liver disease, warfarin therapy, nephrotic syndrome, oral contraceptives, L-asparaginase treatment and pregnancy.
Inherited deficiencies of Protein S are classified into three groups:
-Type I deficiencies correspond to reduced antigen levels of both Total and Free Protein S.
-Type II deficiencies are characterized by a reduced Protein S Activity but with normal antigen levels of both Total and Free Protein S.
-Type III deficiencies are defined by a reduced antigen level and activity of Free Protein S but the antigen level of Total Protein S remains normal.
Classification of inherited protein S deficiency requires both activity and antigenic testing for protein S.
Total Protein S is comprised of Free Protein S and Protein S bound to a complement protein, C4B-BP. The relative proportions of the free and bound forms are 40% and 60%, respectively. It is the free form of Protein S that serves as the cofactor for activated protein C (APC). The APC/free PS complex serves to down regulate thrombin generation via proteolytic inactivation of Factors Va and VIIIa. Therefore, a deficiency in Protein S increases an individual’s risk for thrombosis since the normal mechanism of thrombin inhibition is decreased. Deficiencies of Protein S may be inherited or acquired. Acquired deficiencies of Protein S result from liver disease, warfarin therapy, nephrotic syndrome, oral contraceptives, L-asparaginase treatment and pregnancy.
Inherited deficiencies of Protein S are classified into three groups:
-Type I deficiencies correspond to reduced antigen levels of both Total and Free Protein S.
-Type II deficiencies are characterized by a reduced Protein S Activity but with normal antigen levels of both Total and Free Protein S.
-Type III deficiencies are defined by a reduced antigen level and activity of Free Protein S but the antigen level of Total Protein S remains normal.
Classification of inherited protein S deficiency requires both activity and antigenic testing for protein S.
Performing Laboratory
med fusion
