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Alpha-1 antitrypsin blood test

A1AT test

Alpha-1 antitrypsin (AAT) is a laboratory test to measure the amount of AAT in your blood. The test is also done to check for abnormal forms of AAT.

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How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

There is no special preparation.

How the Test will Feel

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.

Why the Test is Performed

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 AAT deficiency. AAT deficiency is passed down through families. The condition causes the liver to make too little of AAT, a protein that protects the lungs and liver from damage.

Everyone has two copies of the gene that makes AAT. Most people with a lower-than-normal level of AAT have one normal gene for AAT, and one abnormal gene. People with two abnormal copies of the gene have more severe disease.

Normal Results

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

What Abnormal Results Mean

A lower-than-normal level of AAT may be associated with:

Risks

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. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

Related Information

Cirrhosis
Chronic obstructive pulmonary disease (COPD)
Liver cancer - hepatocellular carcinoma
High blood pressure - adults

References

Chernecky CC, Berger BJ. Alpha1-antitrypsin - serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:121-122.

Winnie GB, Boas SR. A1-antitrypsin deficiency and emphysema. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 393.

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Review Date: 7/20/2018  

Reviewed By: Allen J. Blaivas, DO, Division of Pulmonary, Critical Care, and Sleep Medicine, VA New Jersey Health Care System, Clinical Assistant Professor, Rutgers New Jersey Medical School, East Orange, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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