Test Code PRSFUM Protein S Activity, Plasma
Additional Codes
MAYO: S_FX
EPIC: LAB491
Reporting Name
Protein S Activity, PUseful For
Second-order testing for diagnosis of congenital or acquired protein S deficiency for example, as an adjunct to initial testing based on results of protein S antigen assay (free protein S antigen, with or without total protein S antigen assay)
Evaluating patients with a history of venous thromboembolism
Performing Laboratory

Specimen Type
Plasma Na CitSpecimen Required
See Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.
Patient Preparation: Patient must not be receiving Coumadin.
Specimen Type: Platelet-poor plasma
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
2. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.
3. Freeze specimen immediately (no longer than 4 hours after collection) at ≤-40° C, if possible.
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.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Plasma Na Cit | Frozen | 14 days |
Special Instructions
Reference Values
Males: 65-160%
Females
<50 years: 50-160%
≥50 years: 65-160%
Newborn infants have normal or near-normal free protein S antigen (≥50%), although total protein S antigen is usually below the adult reference range. There are insufficient data concerning protein S activity in normal neonates, infants, and children; but normal or near-normal activity (≥50%) probably is present by age 3 to 6 months.
Day(s) Performed
Monday through Friday
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
85306
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
S_FX | Protein S Activity, P | 27822-6 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
S_FX | Protein S Activity, P | 27822-6 |
Report Available
1 to 4 daysReject Due To
Gross hemolysis | Reject |
Gross lipemia | Reject |
Gross icterus | Reject |
Method Name
Optical Clot-Based
Secondary ID
80775Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.