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COPD and Alpha-1 Antitrypsin (AAT) Deficiency

Topic Overview

Alpha-1 antitrypsin (AAT) is a protein normally found in the lungs and the bloodstream. It helps protect the lungs from the damage caused by inflammation that can lead to emphysema and chronic obstructive pulmonary disease (COPD). People whose bodies do not produce enough of this protein (AAT deficiency) are more likely to develop emphysema and do so at a younger-than-normal age (30 to 40 years old). AAT deficiency is a rare disorder and is the only known genetic (inherited) factor that increases your risk of developing COPD.

Your doctor may suspect you have an AAT deficiency if you:footnote 3

  • Develop emphysema at 45 years of age or younger.
  • Develop emphysema without having any recognized risk factors, such as smoking or inhaling industrial dust or chemical fumes over a long period of time.
  • Develop emphysema, and X-rays show less density in the lungs than normal (basilar hyperlucency).
  • Develop unexplained liver disease.
  • Have a family history of emphysema, bronchiectasis, liver disease, or inflammation of the fat under the skin (necrotizing panniculitis).
  • Have bronchiectasis without an evident cause.

An AAT deficiency test measures the level of AAT in the blood. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2019 clinical guidelines recommend a one-time testing for all people with COPD.footnote 1 And the Canadian Thoracic Society suggests testing for an AAT deficiency in people diagnosed with COPD who:footnote 2

  • Are younger than 65 years of age.
  • Have a smoking history of less that 20 pack years. (To figure out your pack years, multiply how many packs a day on average [assuming 20 cigarettes per pack] you have smoked by how many years you have smoked.)


It is extremely important that you do not smoke if you have an AAT deficiency. Smokers with this condition may suffer devastating disease at a young age. People with this condition who have never smoked usually do not have significant symptoms at any age.

Treatment for COPD may include inhaled medicines to help you breathe easier. It may also include participating in a pulmonary rehabilitation program to learn exercise, breathing tips and other ways to help yourself stay as healthy and strong as you can. In addition, your doctor may suggest that you are eligible for alpha-1 antitrypsin protein replacement. To be considered for this treatment, the following are basic guidelines:

  • Your blood levels of the alpha-1 antitrypsin enzyme are less than 11 µmol/L (micromoles per litre).
  • You have the appropriate genetic pattern of alpha 1 anti-trypsin deficiency obtained from a blood test.

Infusions of replacement alpha-1 antitrypsin are given weekly. Talk with your doctor about benefits of the therapy, and if you are eligible for this therapy.



  1. Global Initiative for Chronic Obstructive Lung Disease (2017). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Accessed November 27, 2016.
  2. Marciniuk, DD et al. (2012). Alpha-1 antitrypsin deficiency targeted testing and augmentation therapy: A Canadian Thoracic Society clinical practice guideline. Canadian Respiratory Journal, 19(2): 109–116. Accessed February 12, 2018. [Erratum in Canadian Respiratory Journal, 19(4): 272. Accessed February 12, 2018.]
  3. American Thoracic Society/European Respiratory Society (2003). ATS/ERS: Standards for the diagnosis and management of individuals with alpha1-antitrypsin deficiency. American Journal of Respiratory and Critical Care Medicine, 168(7): 820–822.


Adaptation Date: 8/18/2021

Adapted By: Alberta Health Services

Adaptation Reviewed By: Alberta Health Services

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