Ordering Guidance

For monitoring treatment of antithrombin deficiency disorders, including infusion of antithrombin therapeutic concentrate, order ATTF / Antithrombin Activity, Plasma.

Necessary Information

If patient is being treated with heparin, this should be noted as heparin treatment may lower plasma antithrombin.

Specimen Required

Specimen Type: Platelet-poor plasma

Patient Preparation: Fasting preferred

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Polypropylene vial

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.

2. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

3. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, at-40° C or below.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.