Protein S Activity

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.

This profile helps to confirm and characterize congenital deficiency of protein S.