Protein S Antigen (Free)

General Information

Lab Name: Protein S Ag (Free)
Lab Code: PSAGF
Epic Name: Protein S Antigen, Free
Description: **Laboratory Medicine resident's approval is required for hospital inpatients and patients in Emergency Department.**

The free protein S antigen in plasma is measured by the immuno-turbidimetric method. Protein S exists in two forms in human plasma, free and complexed with C4b Binding Protein. Only the free form of Protein S is known to express biological activity. Free Protein S deficiency is associated with an increased risk of venous thrombosis and the classification of the protein S deficiency is dependent upon the protein S antigen and activity levels. Protein S is a vitamin K depentent factor. Patients on warfarin therapy may see a decrease in Protein S free antigen because of the vitamin K antagonistic effect of the drug. Protein S Free Antigen levels may also be decreased in the setting of acute phase response, acute thrombotic event, hepatic disorder, L-asparaginase treatment, use of oral contraceptives and pregnancy.

Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Forms & Requisitions: Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Synonyms: Fractionated Protein S, Protein S AG-Function, Protein S Level
Components

Interpretation

Method

Optical, Stago STA LIA Free Protein S antigen assay

Reference Range

Units: %

Female		Male
Age	Range	Age	Range
0-2m	15-150	0-2m	15-150
3m-5m	35-150	3m-5m	35-150
6m-11m	47-150	6m-11m	47-150
1y-5y	49-150	1y-5y	49-150
6y-9y	58-150	6y-9y	58-150
10y-	51-150	10y-	69-150

Effective date: 06/10/2010

Ref. Range Notes

Elevated Protein S is not associated with thrombosis or bleeding.

Interferences and Limitations

Clinical assay interference and limitations: The presence of rheumatoid factor, anti-bovine albumin and/or anti-mouse antibodies in the specimen may lead to an over-estimation of the free protein S level. This assay is insensitive to hemoglobin (up to 2 g/L), bilirubin (up to 75 mg/L), fibrinogen (up to 9 g/L), unfractionated heparin (up to 1.5 IU/mL) and low molecular weight heparin (up to 2 anti-Xa IU/mL).

Ordering & Collection

Specimen Type: Blood
Collection: 3 or 5 mL BLUE TOP (CITRATE) tube
Forms & Requisitions: Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Handling Instructions: The Laboratory MUST process specimen, within 4 hrs of blood collection.
Quantity: Requested: entire sample

Processing

Receiving Instructions: **Laboratory Medicine resident's approval is required for hospital inpatients and patients in Emergency Department.** Approval is NOT required for hospital outpatients, clinic patients or outside clients.

UW-MT Instructions: Take sample to UW-MT coag lab for processing. Coag tech will freeze plasma for transport to HMC.

HMC Instructions: Take specimen to HMC Coag lab for processing.

Note: Login PSAGF for requests stating Protein S Antigen or Protein S. If request specifies, Total Protein S Antigen, see RPSAGT

Outside Laboratory: Centrifuge for 10 minutes, remove plasma & re-spin plasma for another 10 minutes. Decant & Freeze plasma (minimum 1.0 mL) @ -20°C to -80°C. Send Frozen on dry ice.

Misc Sendout

Performance

Lab Department

Coagulation(COAG)

Frequency

Run Monday and Thursday. Reported by end of day.

Available STAT?

Performing Location(s)

HMC	Coagulation 206-520-4600 325 9th Ave, Rm # GWH-47, Seattle, WA 98104-2420

Billing & Coding

CPT Codes: 85306
LOINC: 12841-3
Interfaced Order Code: UOW884
Interfaced Result Code: UOW884