Test Directory

• Protein C, Activity
• Protein C, Antigen
• Protein S, Activity
• Protein S Antigen, Total

Aids in characterization of protein C (PC) and/or protein S (PS) deficiency. PC and PS deficiency is associated with increased thrombotic risk and may be congenital or acquired. Acquired PC and 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.

Specimen Type: Platelet-poor plasma 

Collection Container: Light Blue Top (Sodium Citrate) 

Desired Specimen Volume: 4 mL

1. Collect 2 light blue top (sodium citrate) tubes via venipuncture.  
2. Mix gently by inverting 3-4 times.

Platelet-Poor Plasma Processing Instructions

1. Perform platelet poor plasma procedure.
2. Transfer 4 mL of platelet poor plasma into two separate clear aliquot tubes (2 mL in each aliquot tube).
3. Please submit a separate, frozen aliquot tube for each special coagulation assay ordered.
4. Freeze immediately.

Transport to the laboratory frozen. 

• Hemolysis

See patient report.

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

• PC Activity
• PC Antigen
• Protein S Functional
• PS Activity
• PS Antigen
• Protein C Functional