Used to identify and quantitate a Protein S defect or deficiency in those patients subject to recurrent venous thrombosis or pulmonary emboli.
Males: 73 - 130%; Females: 65 - 139%.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Days Test Performed
Soft Order Code
Protein S Antigen, Free
PROTEIN S ANTIGEN FREE
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Offsite Collection Instructions
Collect specimen in a blue top (citrate 3.2%) tube. Mix by inversion. Specimen should arrive at lab within 3 hours of collection; transport at room temperature. Alternatively, centrifuge, aliquot plasma into a plastic vial, and freeze the specimen within 4 hours of collection. Transport frozen specimen on dry ice. Collection of the blood through lines that have been previously flushed with heparin should be avoided. If the blood must be drawn through a VAD (vascular access device), the line should be flushed with 5 mL of saline and the first 5 mL of blood or six dead space volumes of the VAD discarded.
Specimens will be rejected if not properly filled, clotted, grossly hemolyzed, or contaminated with heparin.
This test is not indicated in patients receiving Coumadin (warfarin) therapy.
Full 2.7mL tube or 1mL plasma aliquot
Full 1.8mL tube or 1mL plasma aliquot
Protein S is a vitamin K dependent anticoagulant protein synthesized in the liver (and endothelium). Protein S circulates in plasma alone ("free") or reversibly bound to the complement regulatory protein C4b binding protein (C4bBP). C4bBP is an acute phase reactant and may be increased in inflammatory conditions, causing an acquired decrease of free protein S. Only free protein S has anticoagulant activity.