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Laboratory Test Directory



Name Method Department Units
Antithrombin Chromogenic assay
Core Lab, Coagulation %

Specimen Requirements

Platelet poor plasma

Container Type Container Size Specimen Volume

Blue plastic tube (Citrate)

2.7 mL 2.7 mL

Frozen - 2 week(s)


Blue plastic tube (Citrate)

1.8 mL 1.8 mL

Frozen - 2 week(s)

Specimen Preparation

  • Fill tubes to appropriate mark.
  • Mix by gentle inversion immediately after collection
  • Centrifuge, remove plasma/serum and freeze
  • Plasma must be platelet free

Reasons for Rejection

  • Clotted specimen
  • Gross hemolysis
  • Over or under filled tube
  • Wrong collection tube
  • Gross lipemia
  • Gross icterus
  • Capillary specimen
  • Specimen collected in glass tube


Thrombin inhibitors may lead to an over-estimation of the Antithrombin level. Routine patient specimens are batch tested, typically on Wednesdays. Patients receiving systemic heparin therapy (e.g. ECMO) can be tested more frequently, as clinically indicated. Centrifuge citrate tubes according to Lab policy, remove platelet-poor plasma, pool the plasma, aliquot and freeze. Send a minimum of two (2) aliquots of plasma.

CPT Code

  • 85300