Protein S

Protein S is a topic covered in the Davis's Lab & Diagnostic Tests.

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Protein S antigen, protein S functional.

To assess coagulation function, assist in the diagnosis of disorders such as venous thromboembolus (VTE) or disseminated intravascular coagulation (DIC).

Patient Preparation
There are no food, fluid, or activity restrictions unless by medical direction. Patients should discontinue warfarin therapy for 2 weeks prior to specimen collection, as ordered. Specimen collection should not be performed sooner than 10 days following a thrombotic event.

Normal Findings

Protein S Activity or Functional Protein S (Method: Clot Detection)Protein S Total Antigen (Method: Enzyme Immunoassay)Protein S Free Antigen (Method: Enzyme Immunoassay)
Male 70%–140%Male 80%–130%Male 70%–150%
Female 60%–130%Female 60%–130%Female 50%–120%
Note: Values are significantly reduced in children because of liver immaturity. Levels rise to approximately 50% to 70% of adult levels by age 5 yr and reach adult levels by age 16 yr.

Critical Findings and Potential Interventions

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