Protein S Antigen, Total and Free

Test Code
36457

CPT Codes
85305, 85306

Preferred Specimen
2 mL platelet-poor plasma collected in a 3.2% sodium citrate (light blue-top) tube

Minimum Volume
1 mL

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/mcL). Freeze immediately and transport on dry ice.

Transport Container
Plastic screw-cap vial

Transport Temperature
Frozen

Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen -20°C: 30 days
Frozen -70°C: 1 year

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis

Methodology
Immunoturbidimetric

Setup Schedule
Set up: Tues-Sat p.m.; Report available: Next day

Limitations
Protein S Antigen, Total: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: no effect to decrease; Heparin (UFH or LMWH): no effect; Dabigatran or Argatroban (Thrombin Inhibitors): no effect; Rivaroxaban or Apixaban (Factor Xa Inhibitors): no effect.

Protein S Antigen, Free: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: decrease; Heparin (UFH or LMWH): no effect; Dabigatran or Argatroban (Thrombin Inhibitors): no effect; Rivaroxaban or Apixaban (Factor Xa Inhibitors): no effect.

Reference Range
Protein S Antigen, Total 70-140 % normal
Protein S Antigen, Free  
   Male 57-171 % normal
   Female 50-147 % normal


Clinical Significance
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.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153



The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.