Antithrombin III Activity

Preferred Specimen(s) 2 mL platelet poor 3.2% sodium citrate-anticoagulated plasma collected in a light blue-top tube; separate and freeze immediately

Instructions Draw blood in light blue-top tube containing 3.2% sodium citrate, mix gently by inverting 3-4 times. Centrifuge 15 minutes at 1500 RCF (relative centrifugal force). Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet (buffy) layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Freeze immediately and transport on dry ice.

Transport Container Plastic screw-cap vial

Transport Temperature Frozen

Reject Criteria

  • Hemolysis
  • Received thawed

Methodology Chromogenic Substrate Clinical Significance Aids in the detection of hypercoagulable states associated with venous thrombotic episodes. May be useful in patients who are hyporesponsive to heparin.