Protein S Antigen

Casandra

Casandra Test Code LC11625Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 164517CPT Codes 85305, 85306

Clinical Use

Order Test

Use

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. 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.

Limitations

This test may not provide meaningful results if the patient is on active anticoagulant therapy (e.g., warfarin, heparin). Gross hemolysis, clotted specimens, thawed in transit samples, or improperly labeled specimens will be rejected. Further, total protein S levels are developmentally regulated and may not reach adult reference ranges until six months of age.

Test Details

Methodology

Immunoassay (Latex immunoassay)

Biomarkers

Protein S, Free

Protein

Protein S, Free • Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Protein S, Total

Protein

Protein S, Total • Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

87557-5

Result Codes

27823-4
27821-8

Result Turnaround Time

2-3 days

Specimen

Plasma

Volume

1 mL

Minimum Volume

Not provided

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. Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio. 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. 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.

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.