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Protein S Activity, Clot

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Updated Test Information:

Test Description
Protein S Activity, Clot
Synonym(s)

UOW1155, Protein S-Clot Based
Test ID
PSCLOT
General Information

Protein S activity is a clot-based quantitative assay to measure the functional protein S level for diagnosis of congenital or acquired protein S deficiency. Protein S activity is recommended if initial testing with Free Protein S Antigen (PSAGF) is decreased. Congenital protein S deficiency is characterized by recurrent thrombosis and the classification of the protein S deficiency is dependent upon the protein S antigen and activity levels. Protein S is a vitamin K-dependent protein. Patients on warfarin therapy may see a decrease in protein S activity due to the vitamin K antagonistic effect of the drug. Protein S activity may also be decreased in the setting of acute phase responses, pregnancy, cirrhosis, L-asparaginase treatment, use of oral contraceptives, DIC or acute thrombotic event.


Recommend Free Protein S Antigen (PSAGF) assay if the patient is taking direct oral anticoagulants.
Container Type

3 mL or 5 mL Light Blue Citrate Tube
Specimen Type

Plasma
Specimen Requirements

The Laboratory MUST process specimen, within 4 hrs of blood collection.
Specimen Collection / Processing Instructions

MUST PROCESS WITH 4 HOURS OF COLLECTION
Platelet poor Coag Citrate Specimen processing:
1. Gently invert tube 2-3 times prior to placing in Centrifuge
2. Centrifuge Citrate whole blood at 4500 rpm for 10 minutes
3. Carefully pipette plasma, avoiding the platelet/buffy coat into a plastic vial
4. Centrifuge plasma at 4500 rpm for 10 minutes
5. Pipette the plasma to a plastic vial, leaving the bottom 0.25 mL undisturbed
6. Freeze plasma immediately and transport frozen. 
Minimum Sample Volume

1 mL
Limitations

Patients on direct thrombin inhibitors such as bivalirudin (Angiomax), dabigatran (Pradaxa), argatroban (Novastan) or anti-Xa drugs such as rivaroxaban (Xarelto), apixaban (Eliquis) and edoxaban (Savaysa), may lead to an over-estimation of the protein S level with this assay. Recommend Free Protein S Antigen (PSAGF) assay if the patient is taking direct oral anticoagulants. This assay is not affected by heparin levels up to 1 IU/mL.
Department (code)

Coagulation
Methodology

Stago Staclot Protein S Assay
Testing Schedule

Thursday
CPT Code(s)

85306
Reference Range

Units: %


Male/Female


0-2m          15-150


3m-5m      35-150


6m-11m    47-150


1y-5y          49-150


6y-9y          58-150


10y-             65-150


 
STAT Orderable (Y/N)

No
Performing Lab

UW
LOINC Code(s)
Collection File View/Download File