Summary

• ANA (Antinuclear antibodies) test is used to screen for autoimmune disorders.
• In autoimmune disorders your immune system mistakenly attacks normal cells in your body.
• It does this by making antibodies that trigger inflammation.
• ANA are one type of antibody. This test by itself cannot diagnose an autoimmune disorder. ANA tests can be positive in someone who does not have an autoimmune disorder and negative in someone who does.
• ANA tests can help your medical team make decisions about what further tests you may need to make a diagnosis. 

What are antinuclear antibodies?

Antibodies

Your immune system fights harmful things such as bacteria and viruses by making antibodies. In autoimmune disorders, you make antibodies that mistakenly attack your own body. These are called autoantibodies.

Autoimmune disorders have a systemic effect on the body and are very complex. There are many different types of autoimmune disorders. Levels of certain autoantibodies are raised with certain types of autoimmune disorders, but autoantibodies are also often found in the blood of healthy people.

Individual autoantibody tests cannot give a definite diagnosis. But by measuring the levels of more than one autoantibody and considering them together with your symptoms and the results of other blood tests and imaging tests, your doctors can make decisions about your diagnosis.

Many blood tests can be involved in diagnosing autoimmune disorders. While some tests look for autoantibodies, others test levels of inflammation, and others look for certain conditions that are known to be associated with specific disorders.

There are many different types of autoimmune disorders, and it is important to distinguish between them. Each type affects your body in different ways and symptoms can take months or years to develop.

ANA or Anti-nuclear antibodies

ANA are autoantibodies that attack the nucleus of cells. Most people have them and by the time we are 70, up to 30 per cent of women and 20 per cent of men have enough ANA in their blood to test positive. 

Why get tested?

An ANA test is most often used to diagnose SLE (systemic lupus erythematosus) but is also used in investigating other autoimmune disorders such as RA (rheumatoid arthritis), scleroderma, Sjögren's syndrome, juvenile arthritis, Raynaud’s disease, Addison’s disease, autoimmune hepatitis, dermatomyositis and mixed connective tissue disease. 

Having the test

Sample

Blood.

Any preparation?

None.

Your results

ANA tests are performed using instruments that detect and count antibodies in a sample of blood. A substance is added to the sample that attaches to ANA and lights up if they are present. The ANA show up as fluorescent patterns with different patterns indicating different autoimmune disorders.

What does the result mean?

Your result will be reported as a number plus the name of a pattern. An example of a positive result might be: ‘Positive at 1:320 dilution with a homogenous pattern.’

Number: The number represents the number of antibodies seen in the test sample. Lower numbers are considered negative and higher numbers are positive.

Pattern: Specific patterns are associated with different autoimmune disorders:

Some of the more common patterns include:

• Homogenous (diffuse) - SLE and mixed connective tissue disease.
• Speckled - SLE, Sjogren’s syndrome, scleroderma, polymyositis, rheumatoid arthritis and mixed connective tissue disease.
• Peripheral (outline) - SLE.
• Nucleolar - no definite disease. In scleroderma, this pattern is more likely than others.

Interpretation

Results from an ANA test cannot diagnose an autoimmune disorder by themselves. They need to be used as evidence along with the results of other blood and imaging tests and information about your health.

A negative result means that ANA were not found in your blood and you're less likely to have an autoimmune disorder. But a negative result does not rule out the possibility that you could have an autoimmune disorder.

A high ANA number can be reported for someone who does not show any evidence of an autoimmune disorder and an ANA test result may be positive before symptoms develop, so it may take time to tell the meaning of a positive result if you do not have symptoms. As few as one in 400 people with a positive ANA will have SLE.

Diagnosing autoimmune disorders is challenging and it can take time. Because symptoms may come and go, it may take months or years to show a pattern that suggests possible SLE or any of the other autoimmune diseases.

Even among people who have been diagnosed with lupus, ANA results can vary widely. One person can be in remission at a certain level (reported number) of ANA while another can be extremely ill at the same level.

Positive ANA results are also seen in hypothyroidism and hyperthyroidism and some infections such as hepatitis C and HIV.

SLE (Systemic lupus erythematosus)

All people with SLE will have a positive ANA result. If you test positive, you will need further specific autoantibody tests such as double-stranded DNA anitbody and ENA to diagnose SLE.

A negative ANA result excludes SLE as a diagnosis. It usually is not necessary to immediately repeat a negative ANA test. However, due to the episodic nature of autoimmune diseases, it may be worthwhile to repeat the ANA test at a future date.

Drug induced lupus

Some medications may bring on a condition that includes SLE symptoms, called drug-induced lupus. When the medication is stopped, the symptoms usually go away. Although many medications have been reported to cause drug-induced lupus, those most closely associated with this syndrome include hydralazine, isoniazid, procainamide and several anticonvulsants.

This condition is associated with the development of autoantibodies to histones. Histones are the proteins that provide a framework for your DNA. An anti-histone test may be ordered to support the diagnosis of drug-induced lupus. Anti-histone antibodies are also seen in non-drug induced SLE.

Sjögren’s syndrome

Most people with Sjögren’s syndrome have a positive ANA result. However, a negative result does not rule it out. You will need further tests for two subsets of ANA: Anti-SSA (Ro) and Anti-SSB (La). All people with Sjögren’s syndrome have SSA autoantibodies.

Scleroderma

Most people with scleroderma test positive for ANA. ANA subset tests can help differentiate the two forms of the disease – limited and diffuse. The diffuse form is more severe. 

Other tests you may have

Rheumatoid Factor (RF) 
High levels of rheumatoid factor in your blood are most often related to rheumatoid arthritis (RA) and Sjögren’s syndrome. Almost all people with rheumatoid arthritis and most with Sjögren’s syndrome have RF autoantibodies in their blood although it can take years for them to appear. If you have a negative result your doctors may ask you to repeat the test at a later date. If you have a positive result but do not have rheumatoid arthritis or Sjögren’s syndrome, there may be another reason. RF autoantibodies can be caused by other autoimmune or inflammatory disorders, cancer, viral infection or diseases of the liver, lung or kidney.

Cyclic citrullinated peptide antibody (CCP)

CCP autoantibodies can be useful in diagnosing early rheumatoid arthritis. This is important so that treatment can be started straight away, minimising tissue damage and complications. The CCP test is also more specific for the diagnosis of rheumatoid arthritis than RF autoantibodies, which can be caused by many other conditions. If you are positive for both CCP and RF, it is very likely that you have rheumatoid arthritis. Also, it suggests you may develop more severe symptoms.

HLA-B27 genetic testing

Human leukocyte antigens are molecules found on the surface of white blood cells that help the body’s immune system distinguish between its own cells and foreign substances. Everyone has an inherited combination of HLA on their white blood cells. A particular type called HLA-B27 is linked to certain types of arthritis.

Tests for inflammation

CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate) are tests that measure the amount of inflammation in the body. However, they cannot show where the inflammation is or what is causing it.

More to know?

There are several forms of lupus. SLE is the form that is most commonly referred to when someone mentions lupus. Systemic lupus means that it can affect almost any organ or system in your body. This is the most severe form. There are other forms of lupus that are primarily limited to skin and their symptoms include rashes that may be found in many shapes and locations on the body. A butterfly-shaped rash is commonly seen on or near the face.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

More information

Pathology and diagnostic imaging reports can be added to your My Health Record.

You and your healthcare provider can now access your results whenever and wherever needed. Get further trustworthy health information and advice from healthdirect.