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Test Code Chrom AT-III Chromogenic AT-III Assay

Aliases

AT III Chromogenic Assay

Useful For

Antithrombin III, heparin cofactor I (AT III), has been of increasing interest to clinicians concerned with causes and treatment of thrombotic disorders. In the absence of heparin, AT III is a slow, progressive, irreversible inhibitor of thrombin and other clotting factors and fibrinolytic agents. When heparin is present, AT III becomes a rapid inhibitor of the same enzymes.

Patient Preparation

No special patient preparation required

Special Collection Instructions

Properly filled 9:1 ratio (blood to anticoagulant)

Collection Method

Venous Draw; properly filled 9:1 ratio (blood to anticoagulant)

Minimum Volume

0.5 ml of plasma from a properly filled 1.8 mL or 2.7 mL NaCitrate (light blue) tube

Container

Light Blue Sodium Citrate
 

Preferred Specimen

2.7mL Lt. Blue (3.2% NaCitrate)

Acceptable Specimens

1.8 mL Lt. Blue (3.2% NaCitrate) tube

Reference or Target Ranges

83 - 128%

Reportable Units

% (percentage)

Critical Value

Not defined for this assay

Reasons for Rejection

Hemolysis Threshold N/A
Icterus Threshold N/A
Lipemia Threshold N/A
Interfering Subtances/Other Short draws, over draws, clotted, improperly labeled, hemolyzed, lipemic or icteric samples, samples > 4 hours from collection

Specimen Stability

Ambient Plasma – 4 hours
Refrigerated (4°C to 8°C) N/A
Frozen(-70°C to -20°C) 2 weeks@ -20°C; 1 year @ -70°C

Performance Information

Days and Time Performed Batched weekly Monday-Friday
Expected Turn Around Time Batched Monday – Friday
Expedited Availability Same or next day expedited testing is available for Cardiac ICU and ECMO patients. For same day testing the patient sample must be received in the coagulation lab by 1300. Provider must call the coagulation lab at 882-1293 for expedited testing.
Stat Availability No
Performing Bench Coagulation
Methodology/Method Description Werfen ACL TOPS - Chromogenic Assay

Special Handling

Centrifugation: 5 minutes at 5000 rpm. Plasma must be centrifuged twice
(double spun) to remove platelets. (<10,000 mm3)

Additional Information/Important Notes

Platelet poor plasma must be used for this test.

After being spun down twice, separate plasma into 2 aliquot tubes and transport to University Hospital Laboratory frozen on dry ice.

CPT Codes

85300

Aliases (synonyms)

Antithrombin Activity