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Test Code AT3 Antithrombin III Activity

Important Note

Draw 2 tubes- Must be completely filled

Note: Heparin treatment may lower plasma antithrombin.

If transport to the lab will exceed 4 hours: Immediately centrifuge the specimen 2 times and aliquot 2 mL of plasma into a separate plastic vial.  Send specimen frozen.

Performing Laboratory

Memorial Hospital Laboratory- Automated Procedures  304-388-5953    

Specimen Requirements

Plasma- Light Blue Top, Sodium Citrate

Draw 2 full, tubes by “clean” venipuncture (no excessive trauma).

Immediately after draw, invert tubes several times to mix blood with additive.

Specimen Rejection

  • Improperly labeled, collected, stored, and transported
  • Quantity not sufficient
  • Hemolyzed 
  • Marked lipemia
  • Clotted specimens

Storage and Stability

Room temperature 18-24oC 4 hours
Frozen <-20oC 1 month

Reference Values

83-128%

Methodology

Chromogenic Substrate

Antithrombin III deficiency is thought to be inherited as an autosomal trait and has been associated with recurrent thromboembolic disease. Antithrombin is the plasma protein that inactivates thrombin.

Days Test Set Up and Turnaround

Monday through Friday, Batched on Dayshift Only (7:00am to 2:30pm)

Results are available within 48-72 hours

CPT Coding

85301