Protein S, Free Antigen with Reflex to Protein S, Total Antigen
Also known as: PRS FREE R
Use
The Protein S, Free Antigen with Reflex to Protein S, Total Antigen test is used to detect and subtype protein S deficiency. This assay is particularly useful for patients with suspected hereditary thrombophilia and hypercoagulability. Protein S plays a critical role in the regulation of hemostasis, and deficiencies can lead to an increased risk of thrombotic events. The test should not be ordered if the individual has been on warfarin therapy in the previous 2-4 weeks, as warfarin can lead to decreased free protein S values, potentially skewing the test results.
Special Instructions
If low Protein S Free Antigen is detected, then Protein S, Total Antigen, will be added automatically, and additional charges will apply. It is important for patients to be off warfarin therapy for two weeks for accurate measurement of protein S levels. Patients with conditions such as DIC, liver disease, pregnancy, and inflammatory syndromes may also show decreased levels of free protein S.
Limitations
The test results can be affected by prior warfarin therapy, as warfarin reduces protein S levels. This test has age- and gender-specific reference intervals that need to be interpreted correctly. Results from individuals with inflammatory conditions, liver disease, disseminated intravascular coagulation, or who are pregnant may not reflect true levels of protein S due to these conditions affecting protein levels. The test does not diagnose specific diseases and should be considered in conjunction with clinical findings and other laboratory tests.
FDA ApprovedNew York Approved
Methodology
Immunoassay (Microlatex Particle-Mediated Immunoassay)
Biomarkers
LOINC Codes
- 27821-8
Result Turnaround Time
1-4 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
2 mL
Minimum Volume
1 mL
Container
Lt. blue (sodium citrate) tube, transferred to an ARUP standard transport tube
Patient Preparation
Patients should be off warfarin therapy for two weeks for accurate measurement of free protein S levels.
Storage Instructions
CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered.
Causes for Rejection
Serum, EDTA plasma, clotted or hemolyzed specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 hours |
| Refrigerated | Unacceptable |
| Frozen | 3 months |