Protein S, Total Antigen

PROTSTAG

5165

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

0.5 mL

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.

Plastic vial

Frozen

Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 30 days

Hemolysis • Received room temperature • Received refrigerated • Received thawed

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

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.

70-140 % normal

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).