Antithrombin Activity


Sunquest Code:ANTCH  
Epic Code:LAB311Epic Name:Antithrombin III
Synonyms:Antithrombin III Functional Assay; Antithrombin III Chromogenic; Anti-thrombin
Methodology:Chromogenic (synthetic substrate) activity assay
Turnaround Time:Turnaround time is 4-8 hours if received during lab hours (see Associated Link). With pre-notification, stats are done within 1 hour after receipt in the laboratory.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens



Collection Instructions

Specimen:Blood
Optimal Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Minimum\Peds Volume:1.8 mL (in 2 mL tube) - filled to fill line on the tube.
Container:Blue Na Citrate, 3.2% - fill to fill line on tube
Collection Instructions:See link to specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tube or clotted specimens.


Processing and Shipping

Specimen Processing:See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab Special Coagulation  (UMMC-East Bank)


Interpretive

Critical Range:Less than 30%
Reference Range:

Less than 1 d

42-80 %

1-4 d

51-75%

5-29 d

54-80%

30-89 d

63-93%

90-179 d

85-109%

180-364 d

94-114%

1 y and older

85-135%

 

 

Use:Antithrombin inactivates thrombin and other serine proteases (activated Factors 12, 11, 10 and 9). In the absence of heparin, this process is relatively slow. In the presence of heparin, antithrombin almost instantaneously inactivates thrombin. Direct thrombin inhibitors in the sample lead to an over-estimation of the antithrombin level by this method.


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