Antinuclear Antibody (ANA) Test
If your doctor thinks that you have symptoms of SLE, drug-induced lupus, Sjogren's syndrome, scleroderma or another autoimmune connective tissue disease
A blood sample taken from a vein in your arm
None needed; however, some drugs interfere with the test, so tell your doctor about any medications you are taking.
The ANA test identifies the presence of antinuclear antibodies (ANA) in blood. These antibodies are produced by the body's immune system – the body's defence system against invasion by foreign substances such as viruses and bacteria. Sometimes the immune system malfunctions and produces substances that attack your body's own cells and tissues instead of foreign substances. When this happens, the resulting disease is termed an autoimmune disease . The presence of ANA is associated with several autoimmune diseases but is most commonly seen in systemic lupus erythematosus (SLE).
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed; however, some drugs interfere with the test, so tell your doctor about any medications you are taking.
How is it used?
The test is used predominantly to help diagnose systemic lupus erythematosus (SLE) and drug-induced SLE-like syndrome but may also be positive in cases of scleroderma, Sjögren’s syndrome, Raynaud’s disease, juvenile chronic arthritis, rheumatoid arthritis, antiphospholipid antibody syndrome, autoimmune hepatitis, polymyositis and many other autoimmune and non-autoimmune diseases.
Because the ANA test result may be positive in a number of these other diseases, SLE can be tricky to diagnose correctly and additional tests may be used to help. For example, tests to look for antibodies to ENA and dsDNA are used to help interpret the ANA results. All of the results are used in conjunction with patient symptoms and clinical history to find a diagnosis.
When is it requested?
Autoimmune diseases can present in different ways. Symptoms (such as painful or swollen joints, unexplained fever, extreme tiredness, a red rash) may come and go over time and may be mild or severe. They could be due to a wide range of causes, and it may take months or years for these symptoms to show a pattern that might suggest SLE or any of the other autoimmune diseases. ANA offers a reliable first step or screening test for identifying SLE and some other autoimmune disorders.
What does the test result mean?
It is important to understand that positive ANA results may be found in healthy people without autoimmune disease, particularly the elderly and pregnant people. Therefore positive ANA results in elderly and pregnant patients must be interpreted cautiously making use of all of the clinical information about the patient. Positive ANA results can also be seen in some viral infections or inflammatory conditions that are not autoimmune diseases, so it is important that test results are interpreted with caution. However, more specific tests can be done to help interpret the positive ANA results (see below).
A positive test result together with relevant clinical symptoms suggests the presence of an autoimmune disease and the doctor will then carry out further more specific tests (e.g ENA and dsDNA antibody tests) and consider the clinical history of the patient to assist in making a final diagnosis. Positive ANA results may appear months or years before signs of disease appear, which is a further reason for careful interpretation of all positive ANA results.
About 95% of patients with SLE have a positive ANA test result. If a patient has symptoms of SLE, such as arthritis, a rash, and autoimmune thrombocytopenia (a low number of specialised blood cells called platelets), then they may have SLE. In such cases, a positive ANA result can be useful to support SLE diagnosis. If needed, additional highly specific tests, anti-dsDNA antibodies, and anti-SM antibodies, can help to show with more confidence that the condition is SLE.
A positive ANA test can also mean that the patient has drug-induced SLE-like syndrome. This condition is associated with the development of antibodies to parts of your DNA called histones. An anti-histone antibody test can be used to support the diagnosis of drug induced SLE-like syndrome.
Other conditions in which a positive ANA test result may be seen include:
- Sjögren’s syndrome: Between 50-75% of patients with this condition have a positive ANA test result. Your doctor may want to do two more specific tests, called anti- SSA and anti-SSB antibodies, to help confirm the diagnosis of Sjögren's
- Scleroderma: Around 90% of patients with scleroderma have a positive ANA test. Two forms of this condition exist called ‘limited’ and ‘diffuse’. The diffuse form is more severe. Patients with limited scleroderma may have anti-centromere antibodies, which give a distinctive pattern in the ANA test and are confirmed with a specific anti-centromere antibody test. Patients with diffuse scleroderma may have anti-Scl-70 antibodies.
- A positive result on the ANA test may also show up in patients with Raynaud’s disease, polymyositis, juvenile chronic arthritis, or antiphospholipid antibody syndrome, but a doctor needs to rely on clinical symptoms and history for diagnosis.
A negative ANA result makes SLE an unlikely diagnosis. However, because autoimmune diseases change over time, it may be worthwhile repeating the ANA test in the future. Apart from rare cases, further antibody (subset) testing is not necessary if a patient has a negative ANA result.
Is there anything else I should know?
Some drugs and infections as well as other conditions can give a false positive result for the ANA test. Some (but not all) of these drugs may bring on a condition that includes SLE symptoms, called drug-induced SLE-like syndrome. When the drugs are 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.
Why is it called "anti-nuclear" antibody?
If I have a negative ANA test, will my doctor order any other antibody tests?
My doctor told me my ANA test is positive but isn't sure if I have lupus. How can this be?
The body’s immune system normally produces antibodies that are designed to fight off diseases and infections. In an autoimmune disease, something goes wrong with this system and the person’s body begins producing antibodies that attack their own tissues. Antinuclear antibodies are antibodies that attack the cell nucleus (the central controlling part of the cell). The ANA test looks at the amount of antinuclear antibodies in a person’s blood. A positive result means that you have a higher than "normal" concentration of these antibodies and may be related to lupus or another disease. Alternatively you may be perfectly healthy and you may simply have a higher than normal concentration of these antibodies. Even among people with lupus, these results can vary widely – one person might have no symptoms at a certain level of ANA, while another can be extremely ill at the same level. Your doctor may need to compare your test results as well as the severity of your symptoms over a period of time in order to make a proper diagnosis. This additional time may also allow your doctor the opportunity to eliminate other possible causes for your symptoms.
Is SLE the same thing as lupus?
There are actually three forms of lupus. Systemic lupus erythematosus (SLE) is the form that is commonly called ‘lupus’. ‘Systemic’ means that it can attack almost any organ in your body, and this is the form with the most severe effects. Discoid lupus is always limited to skin and the produces a rash on the face, neck, or scalp. Some drugs can bring on the symptoms of SLE, and this condition is called drug-induced lupus. The symptoms usually fade when the drug is stopped. This form of lupus happens only to an extremely small percentage of patients taking such drugs.
On This Site
Tests: Extractable Nuclear Antigen Antibodies (ENA) Panel, Anti-dsDNA antibodies, Erythrocyte Sedimentation Rate (ESR), C-Reactive Protein (CRP), Complement, Autoantibodies, Anticentromere Antibody, Histone Antibody
Conditions: Systemic Lupus Erythematosus (SLE), Autoimmune Diseases, Rheumatoid Arthritis, Sjögren Syndrome, Scleroderma
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