Orderable EAP code:

LAB00237

Billable EAP Codes:

80001089 x 1

CPT Codes:

85300 x 1

Lab Section:

Core Lab

Includes:

Assay is included with Hypercoaguable Panel

Turnaround Time:

Routine: 2 Hours

Urgent: 1 Hour

Test Schedule:

24 hours, 7 days a week.

Units:

%

Specimen Requirements:

3.2% sodium citrate tubes are acceptable provided they are filed to the line on the manufacturer's label. Tubes must be full (see comments below). Whole blood specimens are stable up to 8 hours at room temperature. Citrate plasma separated from cells is stable for up to 1 month at -20 degrees C. For referral testing, submit at least 1.0 mL frozen platelet poor citrated plasma.

Pediatric Specimen Requirements:

Add blood to the 1.3 mL mark of Pediatric BLUE top tube, 3.2% sodium citrate.

Reference Range:

Less than 1 month: 39% to 108%

1 month up to 3 months: 39% to 124%

3 months up to 6 months: 73% to 124%

6 months up to 1 year: 86% to 118%

1 year and greater: 83% to 128%

Comments:

Draw volume is critical due to the liquid anticoagulant. Allow tubes to fill by vacuum.

• Tubes with rubber stopper: fill to line on label.
• Tubes with plastic (Hemogard) cap: the fill level is above the top of the label.
• Syringe: do not remove the vacutainer stopper. Insert the needle through the stopper and allow the tube to fill by vacuum. Do not overfill the vacutainer.
• Pediatric tubes have no vacuum. Remove the cap and add blood to the 1.3 mL mark. Do not overfill.

Avoid heparin therapy for 2 days prior to the test.

Assay is used to evaluate hypercoagulable state, fibrinogenolytic state, and response to heparin. Test for the hereditary deficiency of antithrombin III (autosomal dominant) which is characterized by predisposition to thrombosis. Acquired deficiency associated with severe cirrhosis, chronic liver failutre, DIC, thrombolytic therapy, pulmonary embolism, nephrotic syndrome, or postsurgical state (especially liver transplant or partial hepatectomy) and due to decreased synthesis, increased loss/consumption, or induced by drugs must be excluded.

Limitations: Assay measures only functional activity. Presence of additional "antithrombins" (distinct from AT III, in particular heparin cofactor II) may contribute to functional "AT III" activity as determined variously by different clinical assays complicating their interpretation and comparability. If specimen contains heparin (as with specimen drawn after heparin flush or patient receiving heparin) results may be decreased. Patients receiving coumarin type anticoagulants may have increased AT III levels.

Methodology: Chromogenic

Decreased Antithrombin III Levels may be due to:

Use of oral contraceptives

Heparin therapy

Disseminated Intravascular coagulation (DIC)

Pulmonary embolism (PE)

Liver diseases

Nephrotic syndrome

Thrombophlebitis

Increased Antithrombin III levels may be due to:

Coumadin-type anticoagulation (low vitamin K)

Bleeding disorder

Kidney transplant

Use of anabolic steroids

Synonyms:

Coags

ATIII

AT III

Antithrombin III Activity

AT III Activity

AT3 Activity

Antithrombin III