Antithrombin Test Enables Early Detection of Thrombosis Risk

Antithrombin ensures balanced blood coagulation by reducing the activity of thrombin and coagulation factor Xa that are responsible for blood coagulation.

Innovance Antithrombin is a new chromogenic test developed by Siemens (Deerfield, IL, USA). It provides automatic quantification of functionally active antithrombin in human citrated plasma. In contrast to antithrombin activity tests based on the inhibition of the coagulation factor thrombin, Innovance Antithrombin determines the activity of the antithrombin protein through the inhibition of coagulation factor Xa. This prevents distortion of the test result if a patient has been given specific medication to prevent or treat thromboses, such as hirudin or other thrombin inhibitors.

The test is based on a chromogenic measurement principle. Citrated plasma is mixed with a surplus of coagulation factor Xa. If heparin is present, part of coagulation factor Xa is bonded and deactivated by the antithrombin present in the specimen. Surplus, uninhibited coagulation factor Xa then splits a chromogenic substrate. In this process, coloring is released, the concentration of which is detected with a photometer. The higher the concentration of the produced coloring, the higher was the quantity of uninhibited coagulation factor Xa and the lower the concentration of functionally active antithrombin originally present in the plasma specimen.

The new test is also suitable for diagnosing congenital or acquired antithrombin deficiencies, which are known to be linked with an increased risk of thrombosis. Antithrombin deficiencies manifest themselves in reduced activity of the antithrombin protein. Two types of congenital antithrombin deficiencies are distinguished: in case of deficiency type I, the total quantity of existing antithrombin protein is reduced, whereas in case of deficiency type II, the protein concentration is normal, but the protein is defective in respect of its inhibitor function.

Acquired antithrombin deficiency exists if less antithrombin protein is produced or more is spent than usual. This may result, for example, from liver diseases, disseminated intravascular coagulation (DIC), sepsis, acute hemolytic transfusion reaction, nephrotic syndrome, or major surgical interventions. The test can also serve for monitoring the substitution therapy with antithrombin concentrates.

Innovance Antithrombin can be used with the automatic coagulation measuring devices from Siemens such as BCS and BCS XP as well as Sysmex CA-500, Sysmex CA-1500 and Sysmex CA-7000.

The Siemens Healthcare Sector is a medical solutions provider with core competence and innovative strength in diagnostic and therapeutic technologies. With its laboratory diagnostics acquisitions, Siemens Healthcare is the first integrated healthcare company, bringing together imaging and lab diagnostics, therapy, and healthcare information technology solutions, supplemented by consulting and support services.

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