Alpha-1 antitrypsin blood test
A1AT testAlpha-1 antitrypsin (AAT) is a lab 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.
Emphysema
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...
Cirrhosis
Cirrhosis is scarring of the liver and poor liver function. It is the last stage of chronic liver disease.
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 variant copies of the gene have lower blood levels and are at risk for more severe disease. Different gene variants may cause differing severity of illness.
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:
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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...
Read Article Now Book Mark Article - Scarring of the liver (cirrhosis)
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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...
Read Article Now Book Mark Article -
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
Dietzen DJ, Willrich MAV. Amino acids, peptides, and proteins. In: Rifai N, Chiu RWK, Young I, Burnham C-AD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. St Louis, MO: Elsevier; 2023:chap 31.
Han MK, Lazarus SC. COPD: diagnosis and management. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 64.
Masson VK, Boas SR. a1 - Antitrypsin deficiency and emphysema. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 442.
Review Date: 8/19/2024
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 C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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