Antithrombin is a small molecule that inactivates several enzymes of the coagulation system. Its affinity for these molecules (i.e. its effectivity) is enhanced by heparin.

GoldBamboo

... Why get tested?
To help investigate the cause of recurrent inappropriate blood clotting; to help diagnose an antithrombin deficiency

When to get tested?
A couple of months after a thrombotic episode; sometimes if you are not responding as your doctor expected to heparin anticoagulation therapy

Sample required?
A blood sample drawn from a vein in your arm
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Lab Tests Online - more...

Antithrombin drawn from PDB 1E03. serpin peptidase inhibitor, clade ...
Wikipedia - [full article]

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