This assay is used as an adjunct to initial testing based on the results of Protein S antigen assay. It helps in evaluating patients with history of venous thromboembolism and diagnosing Congenital / Acquired Protein S deficiency. Only free Protein S has anticoagulant activity.

3 mL Whole blood in 1 Blue Top (Sodium Citrate) tube. Mix thoroughly by inversion. Transport to Lab within 4 hours. If this is not possible, make PPP within 1 hour of collection as follows: Centrifuge sample at 3600 rpm for 15 min. ; transfer supernatant to a clean plastic tube. Centrifuge this supernatant again at 3600 rpm for 15 min. ; finally transfer the supernatant (PPP) to 1 labelled, clean plastic screw capped vial. FREEZE IMMEDIATELY. Ship frozen. Overnight fasting is preferred. Duly filled Coagulation Requisition Form (Form 15) is mandatory. It is recommended that patient discontinues Heparin for 1 day and Oral Anticoagulants for 7 days prior to sampling as these drugs may affect test results. Discontinuation should be with prior consent from the treating Physician.

Immunoturbidimetry

Sample Daily by 11 am; Report Same day

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Overnight fasting is preferred. It is recommended that patient discontinues Heparin for 1 day and Oral Anticoagulants for 7 days prior to sampling as these drugs may affect test results. Discontinuation should be with prior consent from the treating physician. Duly filled Coagulation Requisition Form (Form 15) is mandatory.