Antithrombin
III
Definition:
Antithrombin III acts with heparin
(which increases AT III activity by 1000 fold) to inactivate the following factors:
Principle of test:
Chromogenic assay based on free
thrombin converting a substrate to a colored product.
IXa, Xa, XIa, XIIa,
Fletcher and Fitzgerald
The higher the AT III levels the
less free thrombin will be available to react with the substrate thus less colored product is formed.