Protein S Antigen, Plasma

Free Protein S Antigen; Protein S Antigen, Total and Free; Protein S, Free and Total Antigen; S Protein Antigen; Total Protein S Antigen

Useful for

• Investigation of patients with a history of thrombosis


• If this test result is decreased, then total plasma protein S antigen (PST) will be performed at an additional charge

Citrated Plasma

Light-blue top (3.2% sodium citrate)

• Patient Preparation: Patient must not be receiving heparin or Coumadin


• Specimen Type: Platelet-poor plasma


• Collection Container/Tube: Light-blue top (3.2% sodium citrate)


• Submission Container/Tube: Plastic vials


• Specimen Volume: 1 mL in 2 plastic vials each containing 0.5 mL


• Collection Instructions:
  
  
  
  • Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again
  
  
  • Aliquot 0.5 mL of plasma into 2 plastic vials, leaving 0.25 mL in the bottom of centrifuged vial
  
  
  • Freeze plasma immediately (no longer than 4 hours after collection) at -20^C or, ideally ≤ -40^C
  
  
  • Send specimens in the same shipping container
  
  
  
  


• Additional Information:
  
  
  
  • A double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results
  
  
  • If the patient is being treated with Coumadin, this should be noted. Coumadin will lower protein S
  
  
  • For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing
  
  
  
  

0.5 mL

Frozen: 14 days

• Gross hemolysis


• Gross lipemia


• Gross icterus

• Protein S total antigen results are potentially affected by:
  
  
  
  • Heparin (unfractionated or low-molecular-weight) >4 U/mL
  
  
  • Hemoglobin >2 g/L
  
  
  • Bilirubin >100 mg/L
  
  
  • Rheumatoid factor >300 IU/mL may lead to an overestimation of the result
  
  
  • Antirabbit antibodies: certain subjects may have aberrant results
  
  
  • Lipemic specimen may lead to an overestimation
  
  
  
  


• Free protein S antigen results are potentially affected by:
  
  
  
  • Heparin (unfractionated or low-molecular-weight) >4 U/mL
  
  
  • Hemoglobin >200 mg/dL
  
  
  • Bilirubin >25 mg/dL
  
  
  • Triglycerides >1500 mg/dL
  
  
  • Platelets >10
  
  
  • Rheumatoid factor >900 IU/mL
  
  
  • Factor V Leiden variant (APC-R)
  
  
  
  

PSF, PST: Latex Immunoassay (LIA)

1-3 days

Monday-Friday

Protein S Antigen, Free

85306

Normal, full-term newborn infants or healthy premature infants may have decreased levels of total protein S (15-50%) but because of low levels of C4b-binding protein, free protein S may be normal or near the normal adult level (≥ 50%). Total protein S reaches adult levels by 90 to 180 days postnatal.

PST: Protein S Ag, Total

Mayo

27821-8

Test Definition: PSTF

Coagulation Guidelines for Specimen Handling and Processing