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Alpha-1 Antitrypsin Test

Last updated May 5, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Alpha-1 Antitrypsin Test helps determine the amount of AAT in blood stream and is an early indicator of the health risk for children due to liver dysfunction.


  • A1AT Test
  • AAT Test
  • Alpha1 – Antitrypsin Test

What is Alpha-1 Antitrypsin Test? (Background Information)

  • Alpha-1 Antitrypsin (AAT): It is a protein produced by the liver, responsible for protecting the lungs by neutralizing certain enzymes that could potentially damage them
  • A deficiency in AAT concentration leads to liver damage (in adults and children) and/or lung problems (in adults). This can be due to a genetic disorder or caused by activities, such as smoking, occupation-related smoke hazards, etc. over many years
  • Alpha-1 Antitrypsin Test: This test helps determine the amount of AAT in the blood stream; it is an early indicator of the health risk for children due to liver dysfunction
  • Emphysema, a common degenerating lung disorder in adults, can also be detected using this test

What are the Clinical Indications for performing the Alpha-1 Antitrypsin Test?

Individuals in the following category are prescribed Alpha-1 Antitrypsin testing:

  • Those having a family health history of AAT deficiency
  • Adults (40 years or lesser in age) developing symptoms of emphysema, even though they are not at risk due to smoking or exposure of lungs to smoke and dust
  • Infants and young children, constantly affected by jaundice or other hepatic diseases

How is the Specimen Collected for Alpha-1 Antitrypsin Test?

Sample required: Blood

Process: Insertion of needle into a vein (arm)

Preparation required: None 

What is the Significance of the Alpha-1 Antitrypsin Test Result?

  • The Alpha-1 Antitrypsin concentration levels are just as important as the quality of AAT (functional or dysfunctional) produced. The risks are dependent upon both these factors
  • Abnormal/dysfunctional AAT of low concentration in the blood may indicate an early onset, or full-blown case of emphysema (as the lungs are unprotected) and liver disorders (as the AAT produced are not effective and they accumulate in the liver damaging it)
  • Further, if DNA tests reveal the presence of one or two anomalous copies of the gene SERPINA 1 then, there is a higher chance of the abnormal or low AAT being passed on to subsequent generations
  • The blood level of AAT, maybe normal (or higher than normal), as inferred from the test readings due to factors, such as stress, pregnancy, oral contraceptives, and thyroid infections. This is because AAT is an ‘acute phase reactant’ and chronic inflammatory conditions, infections, and certain cancer types, increase their levels. The test results are not interpreted to monitor these conditions


Additional and Relevant Useful Information:

Alpha-1 Antitrypsin Phenotype test usually follows a positive AAT test and helps identify and measure the quantity of different forms of alpha-1 protein produced. Following this, AAT DNA testing is performed to isolate the kind of gene mutation and the SERPINA 1 gene allele (an alternative form of gene) present. The threats, either to the individuals themselves or to their offspring, are assessed based on these variations.


References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Sept. 4, 2013
Last updated: May 5, 2018