Pathology Handbook

Protein S assay



Clinical Indications

Clinical / family history of thrombotic episodes.

Please refer to Thrombophilia clinic or d/w Consultant haematologist BEFORE making request.

NOT available immediately post thrombosis or while patient on anticoagulant therapy.

It is strongly suggested to request a Thrombophilia screen rather than Protein S assay unless investigating a known low protein S.

Request Form 

Request via ICE


Mon - Fri 9AM to 4PM

Specific Criteria

Patient should be bled with minimal stasis

Patient Preparation

Patient should ideally be at rest and not in acute phase reaction

Turnaround Time

Two weeks


Fresh citrated Blood (within 2 hours of collection)


4.5 ml


4.5ml blue capped vacutainer tube
Vacutainer blue top


CSamples should be taken with minimal stasis and taken to the laboratory as soon as possible

Causes for Rejection

Underfilled, clotted or haemolysed samples

Reference Range

See patient test report