Protein S, Total Antigen

Test Code

PRSTA

Alias/See Also

LAB493

CPT Codes
85305

Preferred Specimen

1 mL citrated plasma collected in a 3.2% sodium citrate (light blue-top) tube

Minimum Volume

0.5 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 -20C: 30 days Frozen -70C: 1 year

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

Hemolyzed samples • 3.8% sodium citrate (light blue-top) tubes

Methodology

Immunoturbidimetric

Setup Schedule

Set up: Tues-Sat; Report available: Next day

Limitations

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.

Reference Range

70-140 % normal

Clinical Significance

Protein S (PS) deficiency may be congenital or acquired and is associated with venous thrombosis. Acquired PS deficiency may occur with vitamin K antagonists/deficiency, liver disease, malignancy, consumptive DIC, surgery, trauma, and hepatic immaturity of the newborn. In addition, PS deficiency is physiologic in pregnancy.

Anticoagulant interference: Vitamin K Antagonists (eg. warfarin) will decrease PS antigen levels. PS antigen testing is not impacted by other anticoagulants (heparins, and target specific anticoagulants such as Dabigatran, Argatroban, Rivaroxaban, Apixaban, Edoxaban).

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

Last Updated: February 23, 2012

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.