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Diagnosis of Alpha-1-antitrypsin Deficiency

How a Diagnosis of Alpha-1-antitrypsin Deficiency is Made


Updated November 30, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Alpha-1-antitrypsin (AAT) deficiency is a genetic disorder that can sometimes lead to cirrhosis and other liver diseases, and/or emphysema. According to the Alpha-1 Association, there are approximately 90,000 people living in the United States with undiagnosed AAT deficiency. On average, a diagnosis of AAT deficiency takes up to 7 years and 3 doctors for discovery.

What is AAT

AAT is a protective protein normally produced by the liver that helps our bodies maintain healthy lung function. Healthy lungs contain a natural enzyme known as neutrophil elastase; under normal circumstances, neutrophil elastase promotes healing of the lungs by digesting damaged, aging lung cells and bacteria that can lead to lung infections. Once healing has occurred, the body calls on AAT to stop the action of neutrophil elastase. When the body doesn't produce sufficient amounts of AAT, neutrophil elastase keeps working and, instead of healing lung tissue, begins to attack and destroy it.

How is AAT Deficiency Related to Lung Disease?

Continued destruction of lung tissue caused by AAT deficiency, and the damaging effects of neutrophil elastase, may eventually lead to lung disease—especially if a person smokes. The lower the level of normal AAT, the greater the risk for developing AAT-deficiency emphysema.

Can I Prevent AAT Deficiency?

AAT deficiency occurs when a child inherits two sets of abnormal AAT genes, one from each parent. Because it is genetic, there's unfortunately no way to prevent it, although you can take certain steps to slow the progressive lung damage that often occurs with the condition.

Testing for AAT Deficiency

Testing for AAT deficiency starts with a simple blood test. The initial test, performed after you've fasted, measures the amount of Alpha-1-antitrypsin in your blood and determines your Alpha-1 antitrypsin genotype. Results from this test reveal whether there is an absence, or deficiency, of Alpha-1-antitrypsin in your blood and if your genotype is normal or defective. Those at greatest risk for AAT deficiency have both a dramatically low concentration of AAT (less than 60 mg/dl) and have two defective alleles in their genotype.

If the AAT test confirms a decreased blood-level of AAT (less than 100 mg/dl) and the genotype test reveals only one, or no deficiency allele (occurs in <4% of all cases), then an Alpha-1-antitrypsin phenotype test should be ordered. The phenotype test compares the amount and type of AAT being produced in a person who is AAT-deficient, with normal patterns of AAT production. If both the AAT level and the the AAT phenotype tests are abnormal, a DNA test may also be ordered, especially if another family member is known to have AAT deficiency.

Who Should Get Tested for AAT Deficiency?

Anyone under the age of 45 who has symptoms of emphysema should be tested for AAT deficiency, especially if they've never smoked or been exposed to other COPD risk factors, and/or their chest X-ray reveals damage in the lower part of the lungs.

Additionally, the American Thoracic Society recommends the following groups of individuals consider testing for the disease:

  • Adults with symptoms of COPD, emphysema or asthma with airway obstruction that's incompletely reversible after aggressive treatment with bronchodilators.
  • Anyone with unexplained liver disease, including babies, children and adults, especially the elderly.
  • Individuals with a history of exposure to identifiable COPD risk factors, who don't yet have symptoms, but whose pulmonary function tests reveal persistent airflow obstruction.
  • Adults with a skin disease known as necrotizing panniculitis.
  • Adults with bronchiectasis of unknown origin.
  • Individuals who have no current symptoms of lung disease, with persistent airflow obstruction, in the absence of risk factors.
  • Teenagers with persistent airflow obstruction as evidenced by pulmonary function testing.
  • Adults with a condition known as C-ANCA-postive vasculitis.
  • Individuals with family histories of AAT deficiency.

How To Get Tested for AAT Deficiency

Only a doctor can diagnose you with AAT deficiency. To be tested, you can either have blood drawn at your doctor's office, or go to an outside laboratory with an order from your doctor. Another option is to order a free Alpha-1 blood sample collection kit and bring it to your doctor, who will collect a few drops of your blood via a finger stick and mail it to a specialized laboratory in Florida. Results that reveal your AAT level and your genotype will be sent back to your doctor, usually in less than two weeks. If your test is normal and you've been diagnosed with emphysema, you can be fairly certain that it wasn't caused by AAT deficiency, but another known risk factor. If the test reveals a decreased level of AAT in your blood, your doctor should discuss the need for further testing to confirm a diagnosis of AAT deficiency and AAT-deficiency emphysema.

How Can I Slow the Progression of AAT Deficiency?

If you have AAT deficiency, the following steps may help you slow its progression:

  • Seek early diagnosis and quit smoking -- Both steps are critical to decreasing the risk of emphysema and slowing the progression of lung function decline associated with AAT deficiency.
  • Avoid environmental risk factors -- Environmental exposure to air pollution, fumes and dust in the workplace, and other airway irritants accelerate lung damage. If at all possible, avoid them completely, or limit your exposure if complete avoidance is not possible.
  • Ask your doctor about augmentation therapy if you have AAT deficiency emphysema -- Although more research is needed to confirm it, augmentation (replacement) therapy may slow the progression of AAT-deficiency emphysema and help reduce emphysema-related mortality rates.
  • Eat properly and exercise regularly -- Among other benefits, a nutritious, well-balanced diet, coupled with a regular exercise program, increases energy and allows oxygen to be utilized more efficiently.


Alpha-1 Association. http://alpha1.org/newly-diagnosed/what-is-alpha-1.

Alpha-1 Foundation. http://alpha-1foundation.org.

American Thoracic Society. ATS/ERS: Standards for the Diagnosis and Management of Individuals with Alpha-1 Antitrypsin Deficiency. Am J Respir Crit Care Med Vol 168. pp 818–900, 2003.

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  6. Diagnosis of Alpha-1-antitrypsin Deficiency

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