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
Synonyms
Fractionated Protein S, Protein S AG-Function, Protein S Level
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
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
**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.
Performance
LIS Dept Code
Coagulation (COAG)
Performing Location(s)
| HMC |
Coagulation
206-520-4600 325 9th Ave, Rm # GWH-47, Seattle, WA 98104-2420 |
|---|
Frequency
Run Monday and Thursday. Reported by end of day.
Available STAT?
No
Billing & Coding
CPT codes
85306
LOINC
Interfaced Order Code
UOW884
Interfaced Result Code
UOW884