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Test Code SFX Protein S Activity, Plasma


Specimen Required


Specimen Type: Platelet-poor plasma

Patient Preparation: Patient must not be receiving Coumadin.

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 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 a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

4. Freeze specimen immediately (no longer than 4 hours after collection) below -40° C.


Secondary ID

617792

Useful For

Second-order testing for diagnosis of congenital or acquired protein S deficiency, ie, 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

Optical Clot-Based

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Reference Values

Males: 65-150%

Females

<50 years: 50-150%

≥50 years: 65-150%

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.

Interpretation

In type I and type III congenital deficiency, free protein S antigen is decreased, and protein S functional activity is similarly decreased. In type II congenital (dysfunctional) protein S deficiency, total and free protein S antigen levels are normal, but functional activity is decreased.

 

Patients with acquired free protein S deficiency associated with inflammation-related increase of C4b-binding protein typically have decreased free protein S antigen and protein S activity with normal (or elevated) total protein S antigen. Acquired protein S deficiency is of uncertain clinical hemostatic significance and is associated with a variety of conditions.

 

Elevated protein S levels are of uncertain clinical significance.

Method Description

The functional activity of free protein S is performed on the instrumentation laboratory ACL TOP. It is determined by measuring the degree of prolongation of a prothrombin time in the presence of the recombinant human tissue factor, phospholipids, calcium ions, and activated protein C. The protein S activity is correlated with the prolongation of the clotting time of protein S deficient plasma to which diluted sample has been added. The clotting time is directly proportional to the amount of functional protein S in the patient's plasma and can be quantified using a standard curve.(Package insert: HemosIL Protein S Activity. Instrumentation Laboratory Company; Rev 08/2012)

Day(s) Performed

Monday through Friday

Report Available

1 to 4 days

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

85306

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SFX Protein S Activity, P 27822-6

 

Result ID Test Result Name Result LOINC Value
SFX Protein S Activity, P 27822-6

Forms

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