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 you might be tested for:
IgA
Also called: Immunoglobulin A
IgA is important in protecting you against infections in your stomach, intestines, sinuses and lungs.
IgG
Also called immunoglobulin G
IgG antibodies are made when your body first responds to an infection. They stay in your body on the lookout in case you get the same infection 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 you get an infection. They act like a red flag, signalling to other parts of your 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.
You can find out more about immunoglobulin tests here
What do my results mean?
You will usually be given the results for all of your immunoglobulin tests together.
Your 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 your food.
Some medicines, such as immunosuppressants and steroids can also cause low immunoglobulins.
Find out more about understanding test results
Liver autoantibody tests
There are three main types of autoantibody that you 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 your blood can be caused by an autoimmune condition called primary biliary cholangitis (PBC).
But other liver conditions can also increase AMA. You will need other tests to confirm your diagnosis.
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 your liver.
If your doctors think you have an autoimmune condition, an ANA test can help them to work out which one it might be. But you will need other tests 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 (SMA)
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.
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 you might have.
What do my results mean?
Your doctor will need to look at the results of your autoantibody tests alongside:
- other test results
- information about your health
- any symptoms you have
- any family history of autoimmune conditions
They might be able to give you a diagnosis based on this or you might need more tests. Find out more about:
- Autoimmune hepatitis (AIH)
- Primary biliary cholangitis (PBC)
- Other liver conditions
- What is autoimmune disease?
- Liver biopsy
- Tests for liver disease
Support for you
The British Liver Trust offers a range of support for people with a liver condition and those closest to them. This includes support groups and an online forum. Support for you.
You can also call or email our helpline. Our friendly team of specialist liver nurses cannot give you a diagnosis or interpret test results. But they can answer questions, offer support, or just listen.
Call the helpline on 0800 652 7330 or find out more here.
We also have lots of information about living with a liver condition:
- Liver blood tests (LFT)
- Tests for liver conditions
- Take our free online screener
- Liver conditions A to Z
- Useful words glossary
- Living with a liver condition
- Eating, drinking and keeping active
- Mental health
Special thanks
We would like to thank the patients and doctors who helped up to create this information. Including Dr Vikki Gordon, Consultant Gastroenterologist and Hepatologist, University Hospital Coventry & Warwickshire.
Published: August 2025
Support for you
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