These blood tests look for antibodies and autoantibodies. They help doctors find out if the immune system is affecting the liver.
Antibodies are an important part of the immune system. They are found in the blood. Their job is to identify and attack things that should not be in the body. Like viruses or bacteria that could cause a disease.
But sometimes the body makes antibodies that attack its own cells. These are known as “autoantibodies”. This can cause autoimmune disease, such as autoimmune hepatitis or primary biliary cholangitis.
Find out more about antibodies, autoantibodies and autoimmune conditions.
Blood tests might look for normal antibodies, autoantibodies, or both.
These tests are often part of a full liver screen. Or you might hear it called an immunology profile test.
On this page:
Having the tests
One sample of blood will be taken, usually from the arm.
It is ok to eat and drink normally before the test.
Tell the medical team about any medicines you or your child are taking. Including over the counter, natural and herbal medicines, and supplements.
Immunoglobulins (normal antibodies)
Also called: serum immunoglobulins, total immunoglobulins, IgA, IgG, IgM
These are helpful antibodies that are important in dealing with infections. There are 3 main types that might be tested for:
IgA
Also called: Immunoglobulin A
IgA is important in protecting against infections in the stomach, intestines, sinuses and lungs.
IgG
Also called immunoglobulin G
IgG antibodies are made when the body first responds to an infection. They stay in the body on the lookout in case the same infection if picked up again.
People with autoimmune hepatitis often have higher levels of IgG.
IgM
Also called immunoglobulin M
IgM antibodies are the first ones to be produced when there is an infection. They act like a red flag, signalling to other parts of the immune system to destroy the infection. The number of IgM antibodies goes down after a few weeks as IgG antibodies start to be made.
People with primary biliary cholangitis (PBC) often have higher levels of IgM.
What do my results mean?
You will usually be given the results for all of the immunoglobulin tests together.
the results will be compared to a reference range. Sometimes called a “normal range”. You can find out more about reference ranges here.
There are lots of medical conditions that can cause an increase in immunoglobulins. These include infections, inflammation, autoimmune conditions, and cirrhosis.
Other medical conditions can cause a decrease in immunoglobulins. For example problems digesting enough protein from food.
Some medicines, such as immunosuppressants and steroids can also cause low immunoglobulins.
Liver autoantibody tests
There are three main types of autoantibodies that might be tested for. You can find out more about each of them, and what a positive test could mean by clicking on the boxes below.
Antimitochondrial antibody (AMA)
A moderate or high level of AMA in the blood can be caused by an autoimmune condition called primary biliary cholangitis (PBC).
But other liver conditions can also increase AMA. Other tests are needed to confirm the diagnosis.
Find out more about the AMA test
Antinuclear antibody (ANA)
There are a few autoimmune diseases that can cause a positive ANA result. It is often found in people who have autoimmune hepatitis.
ANA can also be found in other autoimmune conditions that are not to do with the liver.
If doctors think someone could have an autoimmune condition, an ANA test can help them to work out which one it might be. But other tests are needed as well.
Lots of healthy people also test positive for ANA. For example it is higher than normal during pregnancy and in many older people.
Smooth muscle antibody
A high level of SMA is usually caused by a condition called autoimmune hepatitis (AIH).
However, around 1 in 5 people with AIH will not test positive for SMA. So many people also need to have a liver biopsy to get a definite diagnosis.
More rarely, other liver conditions can cause an increase in SMA.
Find out more about smooth muscle antibody tests
Anti-liver kidney microsomal type 1 antibodies (Anti-LKM-1)
The anti-LKM-1 test is usually done on the same blood sample as the SMA and ANA tests.
These test results are looked at together and are used to diagnose autoimmune hepatitis. They can also help doctors to work out which type of autoimmune hepatitis it is.
Find out more about Anti-LKM tests.
What do the results mean?
The doctor will need to look at the results of the autoantibody tests alongside:
- other test results
- information about your or your child’s health
- any symptoms
- any family history of autoimmune conditions
They might be able to give a diagnosis based on this or more tests might be needed. Find out more about:
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This content was last reviewed: August 2025
Our expert reviewers:
We would like to thank everyone who helped with creating and reviewing this page. Including Dr Vikki Gordon, Consultant Gastroenterologist and Hepatologist, University Hospital Coventry & Warwickshire. And all our patient reviewers.
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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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