Alpha-1-antitrypsin deficiency

How is alpha-1-antitrypsin deficiency diagnosed?

Alpha-1-antitrypsin deficiency (AATD) is diagnosed by a blood test. This measures the level of AAT in the blood. In this section we cover why your doctor might test you for AATD, and what you should do if a family member is diagnosed.

If the level is lower than it should be, some more tests will be done on the blood sample to see what the type is – for example, MZ or ZZ. You should only need this test once.

There are a few reasons why your doctor might decide to test for AATD:

  • They might suspect that you have AATD – for example if you’ve developed emphysema or another lung condition at a young age.
  • Sometimes they do it as a routine test if you’ve been diagnosed with COPD.
  • They might do the test as part of family screening, looking at relatives of people who have diagnosed AATD.
  • They might do the test as part of the investigation of liver disease, particularly in children born with jaundice.

If you’re diagnosed with COPD and especially if you are under the age of 45, you should ask your doctor to consider testing you for AATD. You should also be tested if you’re diagnosed with COPD but have never been a smoker or have only smoked for a few years.

Testing is important to make sure that you’re receiving the correct treatment. AATD causes COPD at an earlier age than usual, so it may be misdiagnosed as asthma. A test will ensure that you’re not being treated for something that you don’t have.

Should I be tested if a family member is diagnosed?

Because AATD is an inherited condition, you’re more likely to have it if a family member has it. If a family member has been diagnosed with AATD, particularly a brother or sister, you should consider being tested yourself. Being aware of your risk helps you take steps to minimise the impact of AATD, for example quitting or never smoking.

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Download our AATD information (PDF, 163KB)

Last medically reviewed: August 2020. Due for review: August 2023

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.