Specimen Requirements
Title
Protein S, Functional
Specimen Requirement
Collect a light blue sodium citrate, immediately invert six times, send whole blood room temperature same day as collected.
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.
Methodology
The patient plasma is added to PS-depleted normal plasma with normal levels of all factors but PS. The mixture is supplemented with excess aPC and factor V is then added. The extent of prolongation of the time to clot formation after calcium chloride is added is proportional to plasma PS activity.
Stability
Room temp: 24 hours, Refrigerated: Unacceptable, Frozen: 28 days
Reference Range
The reference range is determined by the performing laboratory and will show on the report.
Turnaround
2-3 days
Clinical Use
Confirmation and characterization of protein S (PS) congenital deficiency
Test Code
PTSAS