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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Antithrombin III Activity
Test Code216
CPT Codes
85300
Preferred Specimen
1 mL frozen platelet-poor plasma collected in 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.5 mL
Instructions
Please submit a separate, frozen vial for each special coagulation assay ordered.
Platelet poor plasma: Centrifuge light blue-top tube 15 minutes at approx. 1500 x g within 60 minutes of collection. 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. Plasma must be free of platelets (< 10,000/mcL). Freeze immediately and ship on dry ice.
Platelet poor plasma: Centrifuge light blue-top tube 15 minutes at approx. 1500 x g within 60 minutes of collection. 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. Plasma must be free of platelets (< 10,000/mcL). Freeze immediately and ship on dry ice.
Transport Temperature
Frozen
Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 30 days
Refrigerated: Unacceptable
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis • Received thawed • Received refrigerated
Methodology
Chromogenic Substrate
Setup Schedule
Set up: Mon-Fri; Report available: Next day
Limitations
Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: no effect; Heparin (UFH or LMWH): no effect to decrease (UFH may decrease levels physiologically but no assay interference); Dabigatran or Argatroban (Thrombin Inhibitors): may falsely increase; Rivaroxaban or Apixaban (Factor Xa Inhibitors): no effect.
Reference Range
1 day-1 month | 41-108 % normal |
31 days-2 months | 50-120 % normal |
3-5 months | 73-120 % normal |
≥6 months | 80-135 % normal |
Clinical Significance
Aids in the detection of hypercoagulable states associated with venous thrombotic episodes. May be useful in patients who appear to be hyporesponsive to heparin.