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Alpha-1 Antitrypsin Testing
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Alpha-1 Antitrypsin Testing

Alpha-1 antitrypsin (AAT) testing is used to diagnose AAT deficiency, a genetic disorder that can lead to serious lung and liver disease.

What is alpha-1 antitrypsin (AAT) testing?

Alpha-1 antitrypsin (AAT) is a protein produced by the liver that protects the lungs from inflammation and environmental irritants. AAT deficiency is a genetic disorder caused by mutations in the SERPINA1 gene, resulting in insufficient or dysfunctional AAT protein. This deficiency increases the risk of chronic obstructive pulmonary disease (COPD) and liver damage, such as cirrhosis.

There are three types of diagnostic tests:

  • AAT blood level test: Measures the amount of protein in your blood.
  • Genotype test: Identifies common gene mutations.
  • Phenotype test: Checks the function and shape of the AAT protein.

What is it used for?

Testing is used to diagnose AAT deficiency in symptomatic individuals, screen family members of those already diagnosed, and guide treatment choices for associated lung disease.

Why do I need AAT testing?

You may need testing if you have symptoms such as wheezing, shortness of breath, chronic cough, or unexplained liver disease. It is also recommended if you have a family history of AAT deficiency, emphysema, or cirrhosis. In infants, testing is used to investigate jaundice or abnormal liver enzyme results.

What happens during AAT testing?

Testing is performed via a blood draw from your arm, a finger prick, or a cheek swab. These procedures are quick and carry minimal risk, typically limited to slight bruising or pain at the site of a blood draw.

What do the results mean?

Low AAT blood levels suggest a deficiency, which must be confirmed by genotype or phenotype testing. While there is no cure for AAT deficiency, treatments can manage symptoms and prevent progression. Key lifestyle steps include:

  • Quitting smoking (the leading risk factor for lung disease in AAT deficiency)
  • Avoiding alcohol to protect the liver
  • Maintaining a healthy diet and regular exercise
  • Adhering to prescribed medical treatments

If you receive an abnormal result, speaking with a genetic counselor can help you understand the implications for your health and your family.

Frequently Asked Questions

low level suggests a deficiency but is not diagnostic on its own. The clinician will usually order a genotype or phenotype test to confirm the specific mutation or functional defect. Once confirmed, they will discuss treatment options such as augmentation therapy, lifestyle changes, and monitoring for liver disease.
For lung disease, options include regular monitoring, avoidance of smoking and pollutants, pulmonary rehabilitation, and, in severe cases, intravenous augmentation therapy that supplies functional AAT protein. For liver disease, management focuses on avoiding alcohol, monitoring liver function, and in advanced cases, liver transplantation may be considered. All patients should receive individualized care plans from a pulmonologist and hepatologist.===
If you have unexplained shortness of breath, chronic cough, wheezing, or liver enzyme abnormalities, or if you have a family history of early‑onset emphysema, cirrhosis, or known AAT deficiency, your clinician may recommend testing. It is also advised for infants with persistent jaundice or abnormal liver function tests.
The blood level test measures the amount of AAT protein in the bloodstream. A genotype test uses DNA from a blood sample or cheek swab to identify common SERPINA1 mutations (e.g., Pi*Z, Pi*S). A phenotype test evaluates the protein’s functional activity and shape, often using electrophoresis. Each test provides complementary information: level indicates quantity, genotype shows genetic cause, and phenotype shows functional impact.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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