Reduced antithrombin III activity

What it means

An abnormality of coagulation related to a decreased concentration of antithrombin-III.

Antithrombin III (ATIII) inhibits the coagulation cascade by lysing thrombin and factor Xa. The defective inhibition of the coagulation cascade is associated with an increased risk of venous and arterial thrombosis. The physiological target proteases of antithrombin are those of the intrinsic pathway, namely the activated forms of Factor X, Factor IX, Factor XI, Factor XII, and, to a greater extent, Factor II (thrombin), and also the activated form of Factor VII (VIIa) from the the extrinsic pathway.

Rare diseases that can present with this10

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Anti-thrombin III deficiency · Antithrombin III deficiency · Decreased antithrombin III