Anti Thrombin III, Plasma


Anti-thrombin III (ATIII), a serine protease inhibitor synthesised in hepatocytes, is one of the three major natural anticoagulant deterrents to pathologic thrombin generation. The endothelium plays a major role in the regulation of coagulation by the expression of heparan sulphate containing proteoglycans that activate AT III amongst other functions. AT III irreversibly neutralises factors XIIa, XIa, IXa, Xa, and thrombin. Two types of AT III deficiency have been described, quantitative (inherited as an autosomal dominant trait), and qualitative, both of which can lead to hypercoagulable state with the quantitative deficiency being the most common.


ATIII is useful in the differential diagnosis of hypercoagulable states such as recurrent, familial and juvenile deep-vein thrombosis (DVT) with or without pulmonary embolism which occur after exposure to identifiable thrombosis risk factors (for example, pregnancy, postpartum complications, trauma, surgery, immobilisation, or oral contraceptives) as well as arterial thrombosis. Acquired AT III deficiency may be seen in various clinical settings including disseminated intravascular coagulation (DIC), liver disease, the nephrotic syndrome, L-asparaginase chemotherapy, and oral contraceptive use. See Also Protein S Antigen Assay, Free, Plasma

Sample Type, Quantity & Conditions

2 ml Citrated Plasma Frozen

Special Precautions

Separate and freeze immediately. Avoid hemolysed, clotted or thawed samples.Patient Preparation: Avoid heparin therapy for 2 days prior to the test (after consulting physician).

Normal Range

By Report

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