Laboratory Test Guide

Anti Thrombin Activity

General Information

Lab Name

Antithrombin Activity

Lab Code

AT3

Epic Name

Antithrombin Activity

Description

Antithrombin (AT) exerts a powerful and immediate inhibitory action on thrombin in the presence of heparin. The Antithrombin Activity is a chromogenic assay used for diagnosing acquired or congenital antithrombin deficiency. This AT assay will detect both type I and II congenital deficiencies of Antithrombin. In addition, acquired AT deficiencies can be seen in heparin therapy, DIC, nephrotic syndrome, liver disease and L-asparaginase treatment. In some patients, AT deficiency may be associated with increased risk for venous thrombosis and insensitivity to heparin treatment.

Synonyms

Anti Thrombin III, Antithrombin 3, Antithrombin III

Interpretation

Method

Optical, Stago Chromogenic Antithrombin Assay

Reference Range

Units: %

Female		Male
Age	Range	Age	Range
0-29d	41-125	0-29d	41-125
1m-2m	48-125	1m-2m	48-125
3m-	80-130	3m-	80-130

Effective date: 03/09/2010

Ref. Range Notes

Elevated antithrombin is not associated with thrombosis or bleeding.

Interferences and Limitations

Patients on thrombin inhibitors such as hirudin (Refludan), bivalidrudin (Angiomax), Dabigatran (Pradaxa), and argatroban (Novastan) may show interference due to the direct thrombin inhibition. This may cause an over-estimation of the antithrombin concentration. This assay is not affected by therapeutic doses of heparin.

Ordering & Collection

Specimen Type

Blood

Collection

3 or 5 mL BLUE TOP (CITRATE) tube

Forms & Requisitions

Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form

Approval Required

**Laboratory Medicine resident's approval is required for hospital inpatients and patients in Emergency Department.**

Handling Instructions

The laboratory MUST receive and process specimen within 4 hours of blood collection.

Quantity

requested: entire specimen

Processing

**Laboratory Medicine resident's approval is required for hospital inpatients and patients in Emergency Department.** Approval is NOT required for hospital outpatients, clinic patients or outside clients.

UW-MT Instructions: Take specimen to UW-MT Coag for processing. Coag tech will freeze plasma for transport to HMC Coag.

HMC Instructions: Take specimen to HMC Coag bench for processing.

Outside Laboratory: Centrifuge for 10 minutes, remove plasma & re-spin plasma for another 10 minutes. Decant & Freeze plasma (minimum 1.0 mL) @ -20°C to -80°C. Send Frozen on dry ice.

Performance

LIS Dept Code

Coagulation (COAG)

Performing Location(s)

HMC	Coagulation 206-520-4600 325 9th Ave, Rm # GWH-47, Seattle, WA 98104-2420

Frequency

Run Monday and Thursday. Reported by end of day.

Available STAT?

Billing & Coding

CPT codes

85300

LOINC

27811-9

Interfaced Order Code

UOW882

Interfaced Result Code

UOW882