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Orderable Name PSF Protein S Antigen, Free, Plasma


Specimen Required


Only orderable as part of a profile, see PSTF / Protein S Antigen, Plasma.

 

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 plasma into separate plastic vial 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:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.


Useful For

As part of an investigation of patients with a history of thrombosis

Testing Algorithm

If free protein S is below normal range, then total protein S will be performed at an additional charge.

Method Name

Only orderable as part of a profile, see PSTF / Protein S Antigen, Plasma.

 

Latex Immunoassay

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Cit Frozen 14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Reference Values

Only orderable as part of a profile, see PSTF / Protein S Antigen, Plasma.

 

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 C4bBP, free protein S may be normal or near the normal adult level (≥50%). Total protein S reaches adult levels by 90-180 days postnatal.*

 

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

Day(s) Performed

Monday through Friday

Report Available

1 to 4 days

CPT Code Information

85306