Tests and diagnosis
for alpha-1 antitrypsin deficiency
Tests for A1ATD look at the amount of a protein in the blood and if the protein can work normally.
The information on this page is for:
- Adults and children with A1ATD. or suspected A1ATD.
- Family, friends, carers, and healthcare professionals.
On this page:
Who should be tested for A1ATD?
- Babies with prolonged jaundice
- Anyone diagnosed with COPD before 45 years old
- Anyone with COPD who has never smoked or only smoked for a few years
- Anyone with liver disease that could be linked to A1ATD
- Anyone with a parent, brother, or sister who has A1ATD
Tests for alpha-1 antitrypsin deficiency
A1ATD is rare and other conditions can cause similar symptoms. So you or your child may have tests to rule out other conditions before being tested for A1ATD.
Newborn babies with prolonged jaundice should also have an urgent test called a split bilirubin test. This checks for another condition called biliary atresia.
AAT blood test
The first step in diagnosing A1ATD is a blood test to see how much of the AAT protein is in the blood. People with A1ATD usually have less AAT in the blood than normal.
The amount of AAT goes up when someone has an infection. So if someone has an infection it may be best to wait until that is better before having the AAT test.
Protein test
You might also hear this called a “protein phenotype” test.
If the level of AAT in the blood is low, the next test is usually to look at the shape of the protein. This is another blood test.
This can often confirm the diagnosis of A1ATD.
Different gene variants cause different protein shapes. So this test can often help doctors to work out which gene variants someone has.
Genetic testing
You might hear this called “genotype” testing
If the protein test results are unclear, or if the test results and symptoms seem unusual, a genetic test might be recommended. This will confirm which versions of the AAT gene are causing the A1ATD.
Other tests
Liver and lung symptoms of A1ATD are very like the symptoms of a lot of other conditions. So many people with A1ATD will have other tests as well.
These might include:
- Liver blood tests (sometimes called (LFTs) to see how the liver is doing
- Imaging tests such as an ultrasound, MRI, or CT scan to look at the liver
Understanding alpha-1 antitrypsin deficiency test results
Test results can confirm that someone has A1ATD. They can also work out which gene variants are causing it.
It is important to remember that A1ATD affects different people in different ways. The test results cannot predict what will happen to an individual.
But having a diagnosis means that you or your child can get support for any problems. And monitoring to find other possible problems early.
Which family members should have a test for alpha-1 antitrypsin deficiency?
If someone is diagnosed with A1ATD, their close family members should be tested. This includes their:
- children
- brothers and sisters
If you have A1ATD and want to start a family, you might also want to ask your partner to be tested. This will help you to find out how likely it is that your children will inherit the condition.
Find out more about starting a family if you have A1ATD on the Living with A1ATD page.
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This content was last reviewed: June 2026
Our expert reviewers:
We would like to thank everyone who helped with creating and reviewing this page. Including Dr Bill Griffiths, consultant hepatologist, Cambridge university hospitals, Professor Dino Hadzic, consultant paediatric hepatologist, King’s college hospital, Dr Girish Gupte, consultant paediatric hepatologist, Birmingham children’s hospital. And all our patient and family reviewers.
Liver UK thanks Takeda UK for their kind donation to support the development of this information. Takeda UK has had no influence in the initiation, development or content of this project.
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Everyone’s experience of liver disease will be different. Always talk to your specialist medical team for personal advice.
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