Antithrombin III deficiency

Antithrombin (AT) III deficiency (now simply called antithrombin deficiency) refers to a congenital lack of the endogenous anticoagulant antithrombin.

Epidemiology

Antithrombin deficiency is considered the least common of the three main anticoagulant deficiencies (the other two being protein C deficiency and protein S deficiency). Its incidence is thought to be ~1:2000-5000 .

Pathology

Antithrombin is a vitamin K-independent glycoprotein in the coagulation pathway. It is a major inhibitor of thrombin and other coagulation serine proteases, including factors Xa and IXa. The deficiency of antithrombin leads to a procoagulant state which is associated with an increased risk of thrombotic and embolic situations such as:

• pulmonary embolism
• deep venous thrombosis
• acute superior mesenteric vein thrombosis

Radiographic features

Radiology mainly plays a role in identifying thrombotic and embolic complications (see above). It is useful for the radiologist to be aware of the thrombotic risk associated with this deficiency.

Treatment and prognosis

Some publications favor the introduction of long-term oral anticoagulation treatment after the first thrombotic event .