Anti Thrombin III Test

The Antithrombin III blood test has quite a few other names, like, Functional Antithrombin III test or AT III test. When we bleed our body naturally prepares a defence mechanism that prevents excess blood loss. The process is known as clotting. There are clotting factors or proteins which regulate clotting and maintain blood flow into our blood vessels. Sometimes, abnormally high blood clotting or thrombosis can prove to be fatal because blood flow to the vital organs is obstructed. This is averted by Antithrombin which is a natural anticoagulant produced by the body. Antithrombin acts as a blood thinner and regulates blood clotting. If blood clotting happens abnormally or deep vein thrombosis occurs, then Antithrombin III test is ordered to check its level. The reference range for new born is 60% - 90%. For children and adults the range is 80% - 120%.

Before the Antithrombin III test, visit your doctor to discuss all details related to your health condition, current medication and symptoms if any. The doctor may advise to discontinue current medication especially if it is blood thinners like ibuprofen and warfarin. Take note of the instructions and follow them sincerely. It is recommended to wear sleeveless or short sleeve dress to allow easy drawing of blood sample.

The Antithrombin III test primarily determines whether the amount of functional Antithrombin is normal in the body. Lower than normal Antithrombin level indicates Antithrombin deficiency. Then, Antithrombin antigen test is performed. Liver and kidney diseases, certain types of cancer and trauma cause deficiency in Antithrombin. Low levels of Antithrombin could lead to recurring blood clots, deep vein thrombosis and inflamed veins. If the clot or thrombus travels to the lungs, then pulmonary embolus is caused and it is life threatening. Recurrent miscarriages are also caused. Blood clot can lead to heart attack or brain stroke. Higher than normal Antithrombin level does not lead to significant medical conditions and it is not a clinical problem.

Sample collection is done by venipuncture. You will be made to sit comfortably with your arm rested on a supportive prop. A tourniquet is tied to your upper arm to locate the vein easily. An alcohol based antiseptic is applied to the needle site. A disposable needle is gently pushed into the vein and the tourniquet is released. The blood sample drawn is collected in a labelled blue top tube with 3.2% sodium citrate for laboratory testing.