Protein S Activity *

SIM

LAB491

CPT

85306 

Synonyms

Protein S Functional; Protein S Activity 

Specimen Type

Plasma, frozen

Container

Blue-top (sodium citrate) tube

Collection Instructions

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. Do not draw from an arm with a heparin lock or heparinized catheter.

Volume

Volume:  1 mL 

Additional Information

Confirmation and characterization of protein S (PS) congenital deficiency

Patient Preparation

Ideally the patient should not be on anticoagulant therapy. Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test.

Specimen Processing Instructions

Citrated plasma samples should be collected by double centrifugation.

Transport Requirements

Frozen

Specimen Stability

Frozen: 7 days 

Rejection Criteria

Gross hemolysis; clotted specimen; frozen specimen thawed in transit

Reference Range

Reference range accompanies report

Critical Value

Test Includes

Protein S 

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 prolongation of the time to clot formation after calcium chloride is added is proportional to plasma PS activity.

Testing Frequency

LCA

164525 

Reviewed By

Rhonda Crowe

Reviewed Date

2/24/23

Supplemental

* Denotes Reference Lab Test