Protein S Activity, Antigen, Total and Free

What this laboratory test evaluates

DetailsProtein S Activity, Antigen, Total and Free – Protein S deficiency may either be hereditary or acquired and is associated with an increased risk for venous thromboembolic disease. Congenital Protein S (PS) deficiency may be classified based on the PS Antigen (Free and Total) and activity results. Type I deficiency is characterized by a decrease in antigen and activity levels whereas a Type II deficiency will have normal antigen levels but reduced activity. A third classification, Type III deficiency, is characterized by reduced free PS antigen and activity, but normal total PS antigen levels associated with increased C4b binding protein level.

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 (Thrombin Inhibitors): may falsely increase activity; Rivaroxaban, Apixaban, Edoxaban (Factor Xa Inhibitors): may falsely increase activity.

What type of sample is required for this test?1 mL plasma collected in each of two 3.2% separate sodium citrate (light blue-top) tubes
Test ResourcesFor more information, please consult your healthcare provider.

Additional test information

Protein S Activity, Antigen, Total and Free – Protein S deficiency may either be hereditary or acquired and is associated with an increased risk for venous thromboembolic disease. Congenital Protein S (PS) deficiency may be classified based on the PS Antigen (Free and Total) and activity results. Type I deficiency is characterized by a decrease in antigen and activity levels whereas a Type II deficiency will have normal antigen levels but reduced activity. A third classification, Type III deficiency, is characterized by reduced free PS antigen and activity, but normal total PS antigen levels associated with increased C4b binding protein level.

Collection and processing

• Sample type: Plasma
• Fasting: No
• Estimated laboratory processing: Results should be available in 2 – 5 business days after the sample is collected

How Sunridge uses laboratory information

Sunridge considers the medical question, symptoms, history, medications, prior results, and whether the finding could change care before recommending testing. A laboratory result is not interpreted in isolation and does not establish a diagnosis by itself.

Before requesting this test

Availability, collection requirements, eligibility, and processing estimates can change. Sunridge reviews each request and, when appropriate, creates the order through Fullscript. Follow the current instructions supplied with the approved order.