Protein S Activity

SRHC Clients:

• Sample must be collected a SRHC due to stability and special collection requirements
• Patient must be off Coumadin for 2 weeks and Heparin for 2 days prior to collection
• 1 light blue top tube (3.2% Sodium Citrate)
• Must be centrifuged and frozen within 1 hour of collection

LAB491

1779

1 mL platelet-poor citrated plasma  (0.5 mL minimum)

0.5 mL

Preparation of Platelet Poor Plasma

1. Centrifuge light blue-top tube 15 minutes at 3000 rpm within 1 hour of collection.
2. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer, and place into a plastic vial.
3. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (< 10,000/mcl).
4. Freeze immediatelyand ship on dry ice.

Plastic vial

Frozen,  at  -70C

Room Temperature: Unacceptable
Refrigerated (cold packs): Unacceptable
Frozen -70 degrees C: 1 year

Hemolysis is not acceptable
3.8% citrate (light blue-top tube) is not acceptable

Set up: Tues-Sat; Report available: 1-3 days

Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: decrease; Heparin (UFH or LMWH): may falsely increase at values approximately greater than 1.0 IU/mL; Dabigatran or Argatroban (Thrombin Inhibitors): may falsely increase; Rivaroxaban or Apixaban (Factor Xa Inhibitors): may falsely increase.

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: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Vitamin K Antagonists (eg. warfarin):
decrease; Heparin (UFH or LMWH): no effect to falsely increased activity levels at higher levels; Dabigatran or Argatroban (Direct Thrombin Inhibitors): may falsely
increase activity; Rivaroxaban, Apixaban, Edoxaban (Factor Xa Inhibitors): may falsely increase activity.