Veripath Test Directory

Epic Test Name Protein S Antigen
Synonyms Protein S, Total and Free
Description Protein S is a vitamin K-dependent natural anticoagulant. It serves as a cofactor for the anticoagulant effects of activated Protein C. Patients with congenital protein S deficiency have 2- to 11-fold risk of venous thrombosis. Acquired Protein S deficiency is not uncommon in hospitalized patients secondary to vitamin K deficiency. Protein S level is also decreased in patients on warfarin anticoagulation, during pregnancy and following thrombotic events. Therefore, the patients should not be tested for congenital Protein S deficiency when on oral anticoagulation, VIT. K deficiency, during pregnancy and around thrombotic event.
The Protein S Antigen assay is a sandwich ELISA test that quantifies Protein S Total and Free.
Specimen Requirements 
Container Light blue (3.2 % sodium citrate) collection tube
Specimen Type Blood
Preferred Collection Volume 3 mL platelet-poor citrated plasma
Minimum Collection Volume Adult: 2 mL, Neonates : 2 mL
Collection Instructions When drawing specimens for coagulation testing, always draw a "pilot" tube (7-10ml plain red top tube), completely filled. This removes tissue fluid contamination. Samples should be obtained from peripheral vein whenever possible. If drawn from indwelling catheter, the line should be flushed with 15mL of saline. After irrigation, a "pilot" tube should be drawn and discarded.
Specimen Handling In-house patients, transport at room temperature.
Out-side client, follow collection instructions and the steps below:
1. Spin light blue top tube. Remove plasma avoiding platelet/buffy coat layer. Spin plasma again to remove top portion of plasma ans place 1mL of PLATELET-POOR PLASMA in plastic tube. (Glass tube unacceptable). Double-centrifugation is critical for accurate results as platelet contamination may cause erroneous results.
2. Plasma must be frozen within 4 hours of collection. CRITICAL WARNING: Specimens must remain frozen until ready to test. Submit separate aliquots when multiple tests are ordered on the same patient specimen.
Rejection Criteria Hemolysis, clotted, short sample, >4 hrs old (if not frozen), thawed plasma, heparin contamination.
Methodology ELISA
Reference Range TOTAL 66-140; FREE 45-107
CPT Code(s) 85305; 85306
Department Hemostasis/Coagulation
Contact Information Hemostasis Lab; 214-633-4959 Customer Service: 214-633-0400, Toll Free 1-877-887-8136.
Turn Around Time1-7 days
Performed Thursday
Performed by Hemostasis
Updated/Reviewed 07/25/2016