Alpha-1 antitrypsin test

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Alpha-1 antitrypsin is a laboratory test to measure the amount of alpha-1 antitrypsin (A1AT) in your blood.

A1AT test

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

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Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

There is no special preparation.

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

This test is helpful in identifying a rare form of emphysema in adults and a rare form of liver disease (cirrhosis) in children and adults caused by an A1AT deficiency. Alpha-1 antitrypsin (AAT) deficiency is condition passed down through families in which the liver does not make enough of a protein that protects the lungs and liver from damage.

Everyone has two copies of the gene that makes A1AT. Most people with lower than normal levels of A1AT have one normal gene for A1AT, and one abnormal gene. Persons with two abnormal copies of the gene have more severe disease.

Review Date: 05/23/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).