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Test Code PRSFUM Protein S Activity, Plasma

Additional Codes







Reporting Name

Protein S Activity, P

Useful 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

Method Name

Clot-Based End point

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Plasma Na Cit

Specimen Required

See Coagulation Studies in Special Instructions.


Patient Preparation: Patient must not be receiving Coumadin.

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Spin down, remove plasma, and spin plasma again.

2. Freeze specimen immediately 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
Plasma Na Cit Frozen 14 days

Reject Due To


Mild OK; Gross reject


Mild OK; Gross reject





Special Instructions

Reference Values

Males: 65-160%


<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) and Time(s) Performed

Monday through Friday; 12 p.m.

CPT Code Information


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

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 U.S. Food and Drug Administration.

Analytic Time

1 day


If not ordering electronically, complete, print, and send a Coagulation Test Request Form (T753) with the specimen (