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Test Code PST Protein S Antigen, Total, Plasma


Specimen Required


Only orderable as part of a profile. For more information 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, at -40 degrees 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

Aiding in the investigation of patients with a history of thrombosis

Method Name

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

 

Latex Immunoassay

Reporting Name

Protein S Ag, Total, P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Cit Frozen 14 days

Reference Values

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

 

Males: 80-160%

Females:

<50 years: 70-160%

≥50 years: 80-160%

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

Interpretation

Protein S values vary widely in the normal population and are age- and sex-dependent.

 

Table. Types of Heterozygous Protein S Deficiency

Type

Protein S antigen free

Protein S antigen total

Protein S activity

I

Low

Low

Low

II

Normal

Normal

Low

III

Low

Normal

Low

 

Protein S and C4b-binding protein (C4bBP) are coordinately regulated, and an increased total protein S antigen and low free protein S antigen most commonly reflect acute or chronic inflammation or illness with an associated increase in plasma C4bBP.

 

For patients in whom hereditary protein S deficiency is strongly suspected and the free plasma protein S antigen level is normal, consideration should be given to testing of free protein S activity, SFX / Protein S Activity, Plasma, for detecting type II protein S deficiency (which is rare).

 

An increased total protein S antigen is of uncertain clinical significance because free protein S antigen levels are usually normal, in such situations. However, the total protein S antigen level may be helpful in distinguishing acquired versus congenital protein S deficiency. High normal or increased total protein S antigen and reduced free protein S antigen suggests acquired protein S deficiency, as may be seen in pregnancy or inflammation. In contrast, low normal or decreased total protein S antigen and reduced free protein S antigen suggests vitamin K deficiency or a warfarin effect, but also could reflect congenital protein S deficiency (type I or III).

 

Vitamin K deficiency, oral anticoagulant therapy, the presence of liver disease, or disseminated intravascular coagulation/intravascular coagulation and fibrinolysis (DIC/ICF) are common acquired causes of protein S deficiency, which is of uncertain significance when such conditions are present. Concomitant assay of coagulation factor II activity may be helpful in differentiating congenital protein S deficiency from oral anticoagulation effects, but supportive data are currently suboptimal.

 

Differentiation of congenital and acquired protein S deficiency requires clinical correlation and may require repeated laboratory study of the patient and selected family members in some instances. DNA-based testing may be helpful; see GNPRS / Protein S Deficiency, PROS1 Gene, Next-Generation Sequencing, Varies.

Clinical Reference

1. Zoller B, Garcia de Frutos P, Dahlback B. Evaluation of the relationship between protein S and C4b-binding protein isoforms in hereditary protein S deficiency demonstrating type I and type III deficiencies to be phenotypic variants of the same genetic disease. Blood. 1995;85(12):3524-3531

2. Grandrille S, Borgel D, Ireland H, et al. Protein S deficiency: a database of mutations. For the Plasma Coagulation Inhibitors Subcommittee for the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis. Thromb Haemost. 1997;77(6):1201-1214

3. Marlar RA, Gausman JN, Tsuda H, Rollins-Raval MA, Brinkman HJM. Recommendations for clinical laboratory testing for S deficiency: Communication from the SCC committee plasma coagulation inhibitors of the ISTH. J Thromb Haemost. 2021;19(1):68-74

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

85305

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PST Protein S Ag, Total, P 27823-4

 

Result ID Test Result Name Result LOINC Value
PST Protein S Ag, Total, P 27823-4