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.
Forms & Requisitions: Outside clients should fill and submit Coagulation Patient Clinical History Form: Coagulation Patient Clinical History Form
Synonyms: Anti Thrombin III, Antithrombin 3, Antithrombin III
Components

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

Receiving Instructions: **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.

Misc Sendout

Performance

Lab Department

Coagulation(COAG)

Frequency

Run Monday and Thursday. Reported by end of day.

Available STAT?

Performing Location(s)

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

Billing & Coding

CPT Codes: 85300
LOINC: 27811-9
Interfaced Order Code: UOW882
Interfaced Result Code: UOW882