Print this article
Share this page:
Also known as: Functional Antithrombin III; AT III
Formal name: Antithrombin; Activity and Antigen

At a Glance

Why Get Tested?

To help investigate the cause of recurrent or inappropriate blood clotting; to help diagnose an antithrombin deficiency

When to Get Tested?

Preferably a couple of months after a thrombotic episode and not whilst taking, or for at least 6 weeks after taking anticoagulants. Occasionally testing may be requested if you are not responding as your doctor expected to heparin anticoagulation therapy

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

No test preparation is needed.