Antithrombin III blood test

A blood sample is needed .

Certain medicines may affect the results of the test. Your health care provider may tell you to stop taking certain medicines or reduce their dose before the test. Do not stop taking any medicine before speaking with your provider.

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Your provider may order this test if you have repeated blood clots or if blood thinning medicine does not work.

Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.

Lower-than-normal AT III may mean you have an increased risk for blood clotting. This can occur when there is not enough AT III in your blood, or when there is enough AT III in your blood, but the AT III does not function properly and is less active. Abnormal results may not appear until you are an adult. Examples of…

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. Other risks may include: Excessive bleeding Fainting or feeling…

Anderson JAM, Weitz JI. Hypercoagulable states. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice . 8th ed. Philadelphia, PA: Elsevier; 2023:chap 138. Sarode R, Kessler CM. Coagulation and fibrinolysis. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and…