Test Details
Methodology
Total and free PS antigens are measured by latex immunoassay.
Result Turnaround Time
2 - 3 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Test Includes
Protein S, total; protein S, free
Use
This test is used for confirmation and characterization of protein S (PS) congenital deficiency.
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions.
Footnotes
References
Custom Additional Information
See Protein S Deficiency Profile [117754] for more clinical information.
Specimen Requirements
Specimen
Plasma, frozen
Volume
1 mL
Container
Blue-top (sodium citrate) tube
Collection Instructions
Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
Stability Requirements
Temperature | Period |
|---|---|
Frozen | 28 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
Total: In newborns, total PS levels are lower than in adults (12% to 60%). Levels gradually reach adult ranges by six months of age.6
Storage Instructions
Freeze.
Patient Preparation
Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test. Do not draw from an arm with a heparin lock or heparinized catheter.
Causes for Rejection
Gross hemolysis; clotted specimen; frozen specimen thawed in transit; improper labeling
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 164517 | Protein S-Antigen | 87557-5 | 164518 | Protein S, Total | % | 27823-4 |
| 164517 | Protein S-Antigen | 87557-5 | 164519 | Protein S, Free | % | 27821-8 |
| Order Code | 164517 | |||||
| Order Code Name | Protein S-Antigen | |||||
| Order Loinc | 87557-5 | |||||
| Result Code | 164518 | |||||
| Result Code Name | Protein S, Total | |||||
| UofM | % | |||||
| Result LOINC | 27823-4 | |||||
| Order Code | 164517 | |||||
| Order Code Name | Protein S-Antigen | |||||
| Order Loinc | 87557-5 | |||||
| Result Code | 164519 | |||||
| Result Code Name | Protein S, Free | |||||
| UofM | % | |||||
| Result LOINC | 27821-8 |