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Antithrombin (AT) III Activity *

SIM

15061 

CPT

85300 

Synonyms

AT III activity; AT3 activity; Antithrombin  III, functional; Serine Protease Inhibitor, Heparin Cofactor Activity  

Specimen Type

Plasma 

Container

Lt Blue-top  sodium citrate tube (Full)

Collection Instructions

Collect in blue top containing 3.2 % buffered sodium citrate filled to completion to ensure proper blood to anticoagulant ratio; mix sample by gentle inversion at least 6 times.

Volume

Volume: 2 ml.
Min. volume: 1 ml.

Additional Information

Warfarin can increase levels ; Thrombin inhibitors interfere with assay.
Confirmation and characterization of acquired or congenital AT deficiency.

Patient Preparation

Patient should not be on unfractionated heparin therapy because heparin decreases plasma AT levels. Do not draw from an arm with heparin lock or heparinized catheter

Specimen Processing Instructions

Separate plasma from cells

Transport Requirements

Frozen

Specimen Stability

7 days 

Rejection Criteria

Hemolysis; Thawed specimen. Serum or specimen collected with anticoagulant other than sodium citrate. Improperly filled tubes.

Reference Range

Reference range accompanies report.

Critical Value

 

Test Includes

Antithrombin III level 

Methodology

Pt’s plasma is mixed with heparin and thrombin. The extent of thrombin inhibition is proportional to the AT concentration of the pt. sample. Residual thrombin activity is measured as the rate of conversion of a chromogenic substrate and is used to calculate AT concentration.

Testing Frequency

 

LCA

015040 

Reviewed By

Lisa McBride 

Reviewed Date

2/5/2018

Supplemental

*  Denotes Reference Lab Test  

Reviewed by Lisa McBride on February 05, 2018

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