Protein S Antigen, Free
Order Name
PROT S FRE
Test Number: 1507050
Revision Date 05/04/2026
Test Number: 1507050
Revision Date 05/04/2026
| Test Name | Methodology | LOINC Code |
|---|---|---|
|
Protein S Antigen, Free
|
Latex Immunoassay Agglutination | 27821-8 |
| SPECIMEN REQUIREMENTS | ||||
|---|---|---|---|---|
| Specimen | Specimen Volume (min) | Specimen Type | Specimen Container | Transport Environment |
| Preferred | 1.5mL (1) | Plasma | Sodium Citrate 3.2% (Blue Top) | Frozen |
| Instructions | 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. Stability: Room Temperature: N/A, Refrigerated: N/A, Frozen: 28 Days (Freeze Thaw Cycles stable x3) Causes for Rejection: Gross hemolysis; clotted specimen; frozen specimen thawed in transit; improper labeling 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 unless the sample is collected using a winged (butterfly) collection system. With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.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 alternative 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. 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. |
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| GENERAL INFORMATION | |
|---|---|
| Expected TAT | 3-4 Days |
| Clinical Use | The presence of rheumatoid factor may lead to an over-estimation of the free protein S level. The presence of anti-bovine albumin and/or anti-mouse antibodies in certain subjects may lead to an over-estimation of the free protein S level. |
| CPT Code(s) | 85306 |
| Service Provided By |  |
| Lab Section | Reference Lab |