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Antithrombin-iii Test

What is it?

Antithrombin-III (an-tee-THROM-bin) is also called AT-III. It is an anticoagulant (an-tee-ko-AG-u-lant) protein that is naturally found in your blood. An anticoagulant keeps your blood from clotting. This blood test measures the amount of AT-III in your blood.

Why do I need it?

A low level of AT-III may cause clots to form inside blood vessels, even when you are not hurt. Low levels may keep anticoagulant medicine from working if you do have clots inside blood vessels. Low levels of AT-III may run in the family or may be caused by kidney or liver disease. Protein wasting diseases, such as malignancy (mah-LIG-nan-see), also cause low levels of AT-III. Caregivers will explain the test and why you need it.

How do I get ready for the test?

Your caregiver will tell you when to have your blood test done. The blood test may be done before or after eating. You may need to stop taking some medicines before the test. Ask your caregiver if you should wait until after your blood is taken to take your usual medicines.

How is the specimen collected?

A caregiver will put a wide rubber strap around your arm and tighten it. Your skin will be cleaned with alcohol. A small needle attached to a special test tube will be put into a vein (blood vessel) in your arm or hand. The tube has suction to pull the blood into it. When the tube is full, the rubber strap, needle and tube are removed. The caregiver will press a piece of cotton where the needle was removed. You may be asked to hold the cotton in place for a few minutes to help stop the bleeding. Tape may then be put over the cotton on your arm.

What should I do after the test?

You may remove the tape and cotton in about 20 to 30 minutes. Call your caregiver to get the results of your test. Your caregiver will explain what your test results mean for you. Follow the instructions of your caregiver.

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about your lab tests. You can then discuss the results with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.