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Assay Type
Thrombophilia Testing
Protein S clotting assay
Intended Use
ThromboTek PSe is a complete kit for the quantitative determination of Protein S activity in human plasma by clotting assay.
ThromboTek PSe is a factor assay for Protein S activity.
Ordering Information
Catalog # Product Kit Configuration Regulatory Classification Product Insert (PDF)
90-480 ThromboTek PSe 80 – 160 Det 510(k), CE Protein S_IFU


Principle of the Test
The ThromboTek PSe method is similar to a standard factor assay. Dilutions of normal plasma are mixed with Protein S depleted plasma and activated Protein C. After a two minute incubation clotting of the plasma mixture is initiated by addition of an activator reagent that contains rabbit thromboplastin. Under these conditions, the prolongation of clotting time is directly proportional to the concentration of Protein S in the patient plasma.

Protein S deficiency can be both congenital and acquired. Protein S deficiency contributes to hypercoagulability and subsequent susceptibility to venous thromboembolism.

Reporting Units
ThromboTek PSe results are in % Protein S, where 100% Protein S is the activity assumed to be present in pooled normal plasma.
Handbooks and Guidelines
  • Eby C, Chapter 9, “Laboratory Aspects of Thrombophila Testing”, in An Algorithmic Approach to Hemostasis Testing, KottkeMarchant ed., CAP Press, 2008
Related Links
Protein S assay in the Massachusetts General Hospital Clinical Laboratory Handbook Coagulation Test Handbook