Protein S Antigen, Free and Total

Protein S Antigen, Free and Total

Alternate Test Name

Free Protein S Antigen

Epic Mnemonic
Sunquest Mnemonic

LAB3195
PSFRB

Category

Sendouts

Methodology

Microlatex Particle-Mediated Immunoassay

Test Performance Schedule

Monday - Saturday

Result Availability

2 – 4 days

Container

Two (2) Light blue top (3.2% buffered sodium citrate) tubes

Volume

Pref. Vol: 4.5 mL whole blood (tubes must be full)
Min. Vol.: Two (2) separate 1.5 mL platelet poor citrated plasma – frozen aliquots

Collection Instructions

• Routine venipuncture
• Immediately after collection, gently invert tube 5-10 times
• Specimen must be processed within 1 hour of collection
• Platelet-poor plasma: Centrifuge light-blue top for 15 minutes at approximately 1500 g within 1 hour of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer, and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcL).
• Separate plasma into 2 aliquots, minimum of 1.5 mL each
• Freeze immediately

Transportation Instructions

Frozen

Stability

• Room Temperature: 1 hour
• Refrigerated: Unacceptable
• Frozen: 2 months (avoid repeated freeze/thaw cycles)

Causes for Rejection

• Serum, EDTA plasma
• Clotted or hemolyzed specimens

Remarks

Patient should be off warfarin (Coumadin) for at least 2 weeks, or on a stable dose of warfarin for at least 2 weeks before drawing sample

Platelet-poor plasma (PPP) samples obtained by double centrifugation are critical for accurate coagulation studies as platelet contamination may cause spurious results

Panel includes:
Protein S Antigen Total
Protein S Antigen Free

CPT Codes

85306, 83505

Effective/Revised

11/19/2019

Tests for protein C and protein S are two separate tests that are often performed together to help investigate a possible excessive clotting (hypercoagulable) disorderand/or to help diagnose the cause of an inappropriate blood clot such as deep venousthrombosis(DVT) or a venousthromboembolism(VTE).

Normally, protein S combines with protein C and together they help control blood clot formation. However, if there is not enough protein C or S or they are not functioning normally, clot formation can go unchecked, possibly leading to an excessive clotting disorder.

Testing is used to evaluate people who have unexplained blood clots or a family history of blood clots, especially if the blood clot occurs in a relatively young person (less than 50 years old) or has formed in an unusual location, such as the veins leading to the liver or kidney or the blood vessels of the brain. It may also be used when someone has had multiple miscarriages. While immediate treatment of the VTE does not depend on the test result, a health practitioner will want to determine the cause and the likelihood of recurrent clotting once the affected person's condition has stabilized.