Device Description
INTENDED USE
An enzyme-linked immunosorbent assay (ELISA) for the quantitative determination of Free Protein S Antigen in citrated human plasma. For In Vitro Diagnostic Use.
SUMMARY AND EXPLANATION OF THE PROTEIN S TEST
Protein S is a vitamin K-dependent protein synthesized in the liver, vascular endothelium, and megakaryocytes, which plays an important physiologic role in the Protein C Anticoagulant System. This anticoagulant system is one of the major regulators of hemostasis by inhibiting clot formation and by promoting fibrinolysis. Protein S functions as a cofactor for activated Protein C on the vascular membrane to facilitate the degradation of clotting factors Va and VIIIa, down-regulating clot formation. In normal plasma approximately 40% of Protein S circulates as a free molecule, while 60% is complexed with C4b, a plasma protein of the classical complement pathway. Only Free Protein S is functionally active and able to bind to activated Protein C, while the complexed form of Protein S is not.
Protein S deficiency, either congenital or acquired, may lead to serious thrombotic events such as thrombophlebitis, deep vein thrombosis, or pulmonary embolism. The prevalence of Protein S deficiency has been estimated to be less than 1 case per 300 in the general population. Two-thirds of patients with a congenital deficiency of Protein S (levels less than 50% of normal) may present with venous thrombosis in young adulthood. In young patients (<35 years) with a history of thrombosis, the prevalence may be as high as 15 to 18%. Acquired Protein S deficiency may be seen during pregnancy, oral contraceptive or oral anticoagulant therapy, liver disease, diabetes mellitus, postoperative complications, septicemia, and various inflammatory syndromes. A decreased Protein S activity in plasma may be the result of low concentrations or abnormal function of the Protein S molecule.
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