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TEST ID PSTF Protein S Antigen, Plasma

Reporting Name

Protein S Ag, P

Specimen Type

Plasma Na Cit


Specimen Required


Specimen Type: Platelet-poor plasma

Patient Preparation: Patient must not be receiving heparin or Coumadin. If the patient is being treated with Coumadin, this should be noted. Coumadin will lower protein S.

 

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:

1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.

2. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

3. Aliquot 0.5 mL of plasma into 2 plastic vials, leaving 0.25 mL in the bottom of centrifuged vial.

4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally  -40° C or below.

 

5. 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.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Testing Algorithm

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

Method Name

PSF, PST: Latex Immunoassay (LIA)

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Reference Values

TOTAL

Males: 80-160%

Females

<50 years: 70-160%

≥50 years: 80-160%

 

FREE

Males: 65-160%

Females

<50 years: 50-160%

≥50 years: 65-160%

 

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.*

*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing

Day(s) Performed

Monday through Friday

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
PST Protein S Ag, Total, P No No

Report Available

1 to 3 days

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

85306-Free

85305-Total (if appropriate)

Useful For

Investigation of patients with a history of thrombosis

Profile Information

Test ID Reporting Name Available Separately Always Performed
PSF Protein S Ag, Free, P No Yes