Antinuclear Antibody (ANA)

An antinuclear antibody (ANA) test looks for antinuclear antibodies in a person’s blood. ANAs are a type of antibody called an autoantibody, and, like other antibodies, they are produced by the immune system. While healthy antibodies protect the body from pathogens like viruses and bacteria, autoantibodies cause disease by mistakenly attacking healthy cells and tissues.

ANA testing requires a blood sample, which is typically taken from a patient’s arm. Testing for ANAs is used to help diagnose and determine the type of autoimmune disorder affecting a patient.

How to get tested

Testing for antinuclear antibodies is typically performed following a doctor’s recommendation. This test requires a blood sample, which is drawn from a vein in a patient’s arm.

Can I take the test at home?

At-home testing for antinuclear antibodies is not currently available in the United States. Patients who are interested in at-home autoimmune disorder testing may find it helpful to discuss their interest with a doctor.

How much does the test cost?

The cost for antinuclear antibody testing can vary depending on several factors, including:

• A patient’s health insurance coverage
• Where the test is conducted
• If ANA testing is combined with other blood tests

For patients with health insurance, the cost of ANA testing may include additional fees for the blood draw, laboratory analysis, and office visits. If prescribed by a doctor, a patient’s health insurance often covers most or all of these costs. Patient’s should discuss the copays, deductibles, and other fees that may be required.

An antinuclear antibody test is performed on a blood sample, which is taken in a doctor’s office, health clinic, or laboratory.

Before the test

Antinuclear antibody testing requires no pre-test preparation. As with other blood tests, it may still be helpful for patients to discuss any supplements or medications they are taking before the test. Some medications can cause a positive ANA test result. A doctor can also address any questions or concerns a patient has before taking this test.

During the test

To obtain the sample for an antinuclear antibody test, blood is usually drawn from a vein in the patient’s arm using a needle. This process only takes a few minutes.

Once an appropriate vein is located, the health care provider may tie an elastic band around a patient’s upper arm or ask the patient to make a fist. The site is then cleaned before a needle is inserted and blood is collected in a tube. When the tube is full, the elastic band is removed from the arm and the needle is withdrawn from the arm.

Patients may experience pain or stinging when the needle is inserted and removed. After the needle is removed, patients may also feel some throbbing at the site where blood was drawn.

After the test

After the blood draw is complete and the needle is withdrawn, patient’s may be given gauze or cotton and asked to apply pressure to the site where the needle was inserted. Pressure helps reduce bleeding, swelling, and bruising.

Although there is little risk associated with having blood drawn, patients may experience discomfort and minor bruising. Fortunately, side effects are often minor and short lived.

There are no restrictions on activities a patient can engage in after a blood draw for ANA testing.

Receiving test results

How long it takes to receive test results can vary. Results may be available within a few business days, and doctors may review results of ANA testing with a patient after additional tests are completed. When test results are available, they may be shared over the phone, by mail, or electronically.

Interpreting test results

There are several methods to measure ANAs. The most widely used method is a fluorescent antinuclear antibody (FANA) test. A FANA test report includes a negative or positive interpretation, ANA levels, and patterns seen in antibodies during the test.

A negative interpretation indicates that autoantibodies weren’t detected in a patient’s blood sample and the presence of an autoimmune disorder is less likely. A positive interpretation indicates that autoantibodies were detected in a patient’s blood sample.

A positive result on an ANA test does not always indicate that a patient has an autoimmune disorder. Many healthy patients test positive for ANAs. Positive results can also be related to a viral infection, medications, and other health conditions. If test results are positive, a doctor may order follow-up testing, especially if a patient has symptoms of an autoimmune disorder.

Results of ANA testing may include a titer. Antibody titer testing measures the amount of antibodies in the blood and is often reported as a ratio, such as 1:160. Reference ranges indicate the minimum titer ratio that is considered a positive result on this test.

Reference ranges for ANA tests are controversial. Labs may vary in what ratio they interpret as positive for ANAs. Patients may find it helpful to discuss reference ranges with their doctor.

Most FANA test reports also describe staining patterns produced during testing. During FANA testing, a fluorescent dye is attached to antibodies, which reveals patterns when viewed under a special microscope. While a staining pattern can’t definitively diagnose a health condition, some patterns are loosely associated with certain diseases. They also give doctors clues about the type of ANA present in a patient’s blood and can signal the need for additional testing. Staining patterns include:

• Homogenous
• Speckled
• Centromere
• Nucleolar

Another method of ANA testing is a solid phase assay. Solid phase assays represent a collection of techniques used to evaluate blood samples and identify specific autoantibodies. This test may be ordered at the same time as ANA testing, called an ANA panel, or after an ANA test in order to more accurately identify the types of autoantibodies present.

Autoimmune disorders can be difficult to diagnose and patients may find it helpful to work with a rheumatologist in addition to their primary care physician when interpreting results from an ANA test. Rheumatologists are specialists that focus on autoimmune disorders and conditions of the muscles, joints, and bones. Rheumatologists are able to answer questions about autoimmune disorders and interpret ANA test results.

Are test results accurate?

Testing for antinuclear antibodies is a useful test for identifying patients who may have an autoimmune disorder. Like other blood tests though, ANA testing isn’t 100% accurate. When interpreting results of ANA testing, there are several important points about test accuracy to keep in mind:

• Positive results in healthy patients: Between 3 and 15% of healthy patients may test positive for ANAs. Testing positive is even more common in patients over 65 years of age, with approximately 10 to 37% of patients in this age group testing positive despite not having an autoimmune disorder. A positive ANA test result in a healthy patient is sometimes referred to as a false positive.
• Lack of standardization: The level of ANAs that is interpreted as a positive test result varies between laboratories. Some labs may interpret lower levels of ANAs as positive, making this test more sensitive for autoimmune disorders, but also increasing false positive results. Other laboratories may only interpret higher levels of ANAs as positive, increasing the risk of false negative results in which a person tests negative despite having an autoimmune disorder.
• Limitations of solid phase assays: Compared to FANA testing, solid phase assays are capable of detecting fewer types of autoantibodies in a blood sample. This limitation means that patients with types of autoantibodies not detected in a solid phase assay may have false negative ANA test results.

In order to reduce the risk of inaccurate or false positive results, doctors limit ANA testing to patients who have signs and symptoms of having an autoimmune disorder. If doctors order ANA testing for patients without symptoms, there is an increased risk of false positive test results.

Do I need follow-up tests?

Patients often need follow-up testing after an antinuclear antibody test. Specific follow-up tests depend on the results of an ANA test, as well as the results of other tests and a patient’s symptoms.

Follow-up testing may involve a solid phase assay, if not already conducted as part of an ANA panel, and other blood tests to detect antibodies specific to individual autoimmune disorders. An extractable nuclear antigen antibodies (ENA) panel is one test used to identify specific autoantibodies.

Additional follow-up blood tests may include a rheumatoid factor test, a cyclic citrullinated peptide antibody test, testing for infections (including hepatitis B and hepatitis C testing), creatine kinase testing, and urine protein to creatinine testing.

If a patient tests negative for ANA, but the patient’s doctor continues to suspect an autoimmune disorder, follow-up testing may be recommended. Follow-up tests after a negative result may include biopsies, diagnostic imaging tests, and blood tests similar to those used in patients who test positive for ANA.

Questions for your doctor about test results

Patients discussing antinuclear antibody testing with their doctor may find it helpful to review the following questions:

• How do I need to prepare for this test?
• Will additional tests or panels be performed at the same time as the antinuclear antibody test?
• How does my test result help me understand the cause of my symptoms?
• Do I need any follow-up tests based on my test result?