Antithrombin Activity (AT3)
Department: Coagulation
Test Synonym(s): LAB311, Antithrombin 3 Activity, AT3, Antithrombin III Activity, AT Act
CPT Codes: 85300
Methodology: Chromogenic
Reference Range: 75 - 140%
Tube Type: One 2.7mL Light blue top - 3.2% Sodium Citrate
Specimen: Citrated plasma - platelet poor. This sample requires double centrifugation if sending a plasma aliquot
Alternate Specimen: None
Pediatric Requirements: Pediatric: One 2.7mL Light blue top - 3.2% Sodium Citrate. Neonatal: One 1.8mL Light blue top - 3.2% Sodium Citrate.
Volume: 1.0 mL plasma
Minimum Volume: 1.0 mL plasma
Temperature: Room temperature or send as a frozen plasma aliquot if sample will not be received into the lab within 4 hours
Stability: Room temperature: 4 horus, Frozen: -70C for one month
Reasons for Rejection: Clotted sample, incorrectly filled tube, grossly hemolyzed plasma, grossly lipemic plasma, sample sent as whole blood >4 hours old.
Days Performed: Daily
Times Performed: Continuous
TAT: 4 hours
Significance: Direct Thrombin and Indirect anti-Xa inhibitors may interfere with this assay.
Special Instructions: Indwelling line should be flushed with saline and 5.0 mL of blood discarded before collecting samples for coagulation assays. Tube must be full and not clotted. Deliver to lab immediately. Samples received from an outside lab must be aliquoted and frozen. Samples aliquoted for shipping must be double centrifuged prior to freezing. Grossly hemolyzed, icteric or lipemic samples may be rejected.
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