Home
HelpTest Code PSTF Protein S Antigen, Plasma
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PST | Protein S Ag, Total, P | No | No |
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Plasma Na CitSpecimen 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 |
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
CPT Code Information
85306-Free
85305-Total (if appropriate)
Report Available
1 to 3 daysSpecimen Retention Time
7 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |