Alpha-1 antitrypsin blood test
A1AT testAlpha-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.
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.
AAT deficiency
Alpha-1 antitrypsin (AAT) deficiency is a condition in which the body does not make enough of AAT, a protein that protects the lungs and liver from d...
Everyone has two copies of the gene that makes AAT. People with two abnormal copies of the gene have more severe disease and lower blood levels.
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:
-
Damage of the large airways in the lungs (bronchiectasis)
Bronchiectasis
Bronchiectasis is a disease in which the large airways in the lungs are damaged. This causes the airways to become permanently wider. Bronchiectasis...
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Scarring of the liver (cirrhosis)
Cirrhosis
Cirrhosis is scarring of the liver and poor liver function. It is the last stage of chronic liver disease.
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Chronic obstructive pulmonary disease (COPD)
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease (COPD) is a common lung disease. Having COPD makes it hard to breathe. There are two main forms of COPD:Chroni...
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Liver tumors
Liver tumors
Hepatocellular carcinoma is cancer that starts in the liver.
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Yellowing of the skin and eyes due to blocked bile flow (obstructive jaundice)
Obstructive jaundice
Jaundice is a yellow color of the skin, mucus membranes, or eyes. The yellow coloring comes from bilirubin, a byproduct of old red blood cells. Jau...
Read Article Now Book Mark Article - High blood pressure in the large vein that leads to the liver (portal hypertension)
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:
- Fainting or feeling lightheaded
- Multiple punctures to locate veins
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk anytime the skin is broken)
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, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 421.
Review Date: 7/31/2022
Reviewed By: Denis Hadjiliadis, MD, MHS, Paul F. Harron, Jr. Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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