Sign in →

Test Code LAB8751 Protein S Antigen, Plasma

Additional Codes

PSTF

Useful For

Investigation of patients with a history of thrombosis

Profile Information

Test ID Reporting Name Available Separately Always Performed
PSF Protein S Ag, Free, P No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
PST Protein S Ag, Total, P No No

Testing Algorithm

If this test result is decreased, then total plasma protein S antigen will be performed at an additional charge.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma Na Cit


Specimen 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
Medical University of South Carolina Note:

On-campus collections: Tube to 99 or deliver to University Extension Hospital Room EH318. 
 
Off-campus collections: Centrifuge and aliquot within 2 hours.Specimen to be stored/transported Frozen.

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)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PSTF Protein S Ag, P 87557-5

 

Result ID Test Result Name Result LOINC Value
PSF Protein S Ag, Free, P 27821-8

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, S_FX / 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 (Coumadin) effect, but also could reflect congenital protein S deficiency (type I or III).

 

Vitamin K deficiency, oral anticoagulant therapy, 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 PRSNG / Protein S Deficiency, PROS1 Gene, Next-Generation Sequencing, Varies.

Method Description

Total:

This assay is performed using the Diagnostica Stago LIATEST Protein S Kit on the Beckman Coulter ACL TOP. Protein S total antigen is determined using automated latex immunoassay methodology. This methodology is comprised of a reagent with microlatex particles coated with specific antihuman total protein S antibodies. Patient plasma containing total protein S antigen is combined with the latex reagent causing the antibody-coated latex particles to agglutinate and form aggregates. The aggregates form diameters greater than the wavelength of the light (405 nm) passing through causing absorption of the light. This change in absorption is measured over time and reported as delta optical density (OD). The increase in absorption is proportional to the concentration of protein S total antigen present in the patient plasma.(Package insert: Liatest Protein S, Diagnostica Stago; 11/2015)

 

Free:

This assay is performed using the HemosIL Free Protein S kit on the Beckman Coulter ACL TOP. The assay uses latex immunoassay methodology to determine the presence of free protein S. It consists of 2 latex reagents, one being latex particles coated with purified human C4BP and the other is latex particles coated with a monoclonal antibody directed against human protein S. Patient plasma is combined with the purified C4BP which reacts with a high affinity for free protein S in the patient plasma. The free protein S adsorbed on the C4BP latex triggers the agglutination reaction with the second latex reagent. The aggregates form diameters greater than the wavelength of the light (405 nm) passing through causing absorption of the light. This change in absorption is measured over time and reported as delta OD. The increase in absorption is proportional to the concentration of free protein S antigen present in the patient plasma.(Package insert: HemosIL Free Protein S. Instrumentation Laboratory Company; 04/2019)

Report Available

1 to 3 days

Specimen Retention Time

7 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Method Name

PSF, PST: Latex Immunoassay (LIA)

Secondary ID

83049