An antinuclear antibody (ANA) test checks your blood for certain types of antibodies called autoantibodies. Autoantibodies commonly develop in people with autoimmune conditions, but they can show up in anyone.
Your doctor will order an ANA test if you have symptoms of an autoimmune disorder. They can use ANA testing to get clues about which tests to run next. The test results can be helpful when diagnosing connective tissue disorders.
Connective tissue disorders are a group of autoimmune conditions. They can cause your immune system to accidentally attack the structures of your muscles and nerves. Keep in mind that an ANA test can't diagnose any specific autoimmune condition. It only tells your doctor that you have autoantibodies.
What Are Autoantibodies?
Usually, antibodies tag certain proteins to help your immune system fight off infections and clear foreign invaders from your body. Autoantibodies mistake your healthy proteins for bacteria, viruses, or other germs and attack them.
An ANA test screens for these autoantibodies that attack your healthy cell proteins. Some experts think a better name for ANAs are "anticell" antibodies. The ANA test can show if you have autoantibodies to three types of proteins that:
- Help control your cell or the command center (nucleus)
- Sit inside the cell fluid or cytoplasm
- Help your cell divide, also called mitotic proteins
Types of ANA tests
There are three main ways to test for anti-cell antibodies. It depends on the test, but autoantibodies light up to show different patterns. These patterns can help your doctor know what to do next.
"ANA (antinuclear antibody) is the familiar test [name] for autoantibody staining performed and reported by many laboratories worldwide," says Edward K.L. Chan, PhD, a professor emeritus in the Department of Oral Biology at UF Health, and co-coordinator of the International Consensus on ANA Patterns (ICAP) in Gainesville, Florida. "But 'HEp-2 IFA' is the precise name for the assay," he says.
How Antinuclear Antibody Testing Works
Your doctor will first review your medical history, do a physical exam, and check for autoimmune symptoms. The ANA test is most helpful in supporting the diagnosis of some types of connective tissue problems.
Even though the ANA test can't diagnose your condition, it can help your doctor know what to do next. If you have a positive ANA test and autoimmune symptoms, your doctor can:
- Order more tests
- Check for specific types of autoantibodies seen in some autoimmune conditions
How is ANA testing done?
The most widely used test for antinuclear antibodies is called IFA-HEp-2. It is done using:
- Your blood sample
- Glass slide and microscope
- Man-made antibody with a fluorescent dye
- Special HEp-2 cells grown in the lab
If you have autoantibodies, they will attach to the HEp-2 cell proteins. Next, the fluorescent antibody will attach to your antinuclear antibodies and light up. The glowing lights from the your autoantibodies can make patterns under the microscope such as speckled, spread out (diffuse), and more.
What is a cutoff?
Depending on the ANA test, results are evaluated against a threshold known as a cutoff. This cutoff helps your doctor know how likely your test result is linked to certain autoimmune conditions.
A laboratory technician prepares your blood sample using a solution that thins out (dilutes) your blood to test different cutoffs. Many labs use the 1:80 and 1:160 cutoffs, but other dilution levels can also be used.
Chan says the lower 1:80 cutoff may be more sensitive, which means that this dilution can correctly identify people who need more testing for autoimmune conditions. But he says that this 1:80 cutoff can also pick up a higher number of people without health problems.
So, your doctor will also combine clinical symptoms and other testing before making a diagnosis.
Why Would a Doctor Recommend an Antinuclear Antibody Test?
ANA testing is most helpful if you already have signs of an autoimmune condition. Your lab report will have the specific cutoff used for your testing. This can help your doctor know:
- How sensitive the test was in your case
- About next steps
Chan says that a positive ANA test isn't as useful if it is at a lower cutoff and you don't have symptoms. Here are some specific autoimmune symptoms that your doctor may check for before ordering an ANA test.
| Autoimmune Condition | Common Symptoms for ANA Testing |
|---|---|
| Systemic lupus erythematosus (SLE) |
|
| Sjögren's disease |
|
| Systemic sclerosis |
|
| Mixed connective tissue disease |
|
Preparing for an ANA Test
You don't need to prepare for an ANA test, unless you are getting other blood tests at the same time. You can usually eat and drink as normal on the day of the test. Follow your doctor's directions, and tell them if you are taking any:
- Medicines
- Vitamins
- Supplements
Antinuclear antibody test risks
The blood test has very few risks. You might feel a slight sting as your blood is taken or notice a small bruise later. You may also have a slight chance of:
- Dizziness or fainting
- Bleeding
- Soreness
Antinuclear Antibody Test Results
ANA testing screens for autoantibodies in your blood. But some people, especially older adults, can have autoantibodies even with no underlying health conditions.
"An 'ANA' result is not a diagnosis," Chan says. The ANA test can help link certain symptoms with autoimmune conditions.
What does a positive ANA test mean?
A positive ANA test means you have autoantibodies that make a specific ANA pattern. ANA testing uses a fluorescent stain that lights up under the microscope. The specific pattern of lights can help link your symptoms to certain connective tissue conditions.
What does the pattern on my ANA test result mean?
Your ANA staining pattern gets an "anti-cell" code such as AC-1. The pattern is matched to one of three groups. This means you may have autoantibodies against the cell:
- Nucleus, patterns AC-1 to AC-14
- Cytoplasm, AC-15 to AC-23
- Mitotic proteins, AC-24 to AC-28
Each pattern is linked to autoimmune symptoms that help your doctor narrow down which condition you might have. Next, they'll run tests to confirm your diagnosis.
The ICAP committee put the ANA patterns into groups to help doctors learn easier ones first, before moving on to the harder stains. "This approach is similar to learning a new language, where foundational vocabulary is acquired before progressing to more advanced terms," Chan says.
Conditions That Cause a Positive ANA Test
Your clinical symptoms, medical history, and additional testing help your doctor confirm a diagnosis. Here are the main connective tissue disorders most likely linked to a positive ANA test:
- SLE, the most common type of lupus
- Scleroderma, a connective tissue disease
- Sjögren's disease, that causes dry eyes and mouth
- Mixed connective tissue disease, a condition that has symptoms of lupus, scleroderma, and polymyositis
The ANA test result can sometimes be positive if you have:
- Raynaud's syndrome, a disease that makes your fingers and toes turn blue and feel cold
- Thyroid diseases such as Hashimoto's thyroiditis or Grave's disease
- Liver diseases such as autoimmune hepatitis or primary biliary cirrhosis
- Inflammatory bowel disease
- Lung diseases such as idiopathic pulmonary fibrosis
What does a negative ANA mean?
A negative ANA pattern, or AC-0, means there wasn't any staining or glowing lights seen under the microscope. This is more likely to happen if your chances of an autoimmune disorder were low before testing or you didn't have symptoms.
Keep in mind that a negative ANA doesn't rule out an autoimmune condition. That's because your body might develop autoantibodies later in time.
Who is more likely to have a false positive ANA test?
ANA testing can still show autoantibodies even if the cause isn't an autoimmune condition. Your doctor will review the cause for autoantibodies showing up without an autoimmune condition, especially if you:
- Are 65 years or older
- Have a viral infection
- Take certain medicines
- Have cancer
- Have a long-term infection
The AC-2 pattern is most common in people without autoimmune problems or symptoms.
Next Steps After an ANA Test
The ANA test only shows if you have autoantibodies; it can't make a diagnosis. "The ANA result establishes an immunologic context; it is not usually a disease activity 'thermometer,'" Chan says.
If your ANA test is positive, your doctor will probably order more tests, including:
- An extractable nuclear antigen (ENA) panel to take the proteins (antigens) out of the cell, which can help your doctor see which autoimmune condition you may have
- Anti-double-stranded DNA (anti-dsDNA) or anti-histone test to look for lupus
- Anti-centromere test to check for scleroderma
You can ask your doctor:
- What do my test results mean?
- Which pattern did my ANA test result show? Does that suggest more tests for a certain autoimmune condition?
- What other tests do I need to confirm my diagnosis?
Find out how your test results will affect your treatment. Your doctor can help you make the best treatment plan for your condition.
Takeaways
An antinuclear antibody (ANA) test is a blood test that looks for certain kinds of autoantibodies in your blood. If you have symptoms, your doctor can use the test to order more testing and check for autoimmune conditions such as systemic lupus erythematosus (SLE), scleroderma, Sjögren's disease, or mixed connective tissue disorder.
Antinuclear Antibody Test FAQs
Should I see a rheumatologist if my ANA is positive but I feel completely fine?
No. In fact, one study reported that fewer than 10% of people who went to see a rheumatologist for ANA testing actually had an autoimmune condition. Everyone has small amounts of autoantibodies. That's why about 20% of people with no health conditions can get a positive ANA test.
"ICAP's approach is pattern- and clinical-context guided, rather than 'every positive ANA gets every possible test,'" says Chan.
After a positive ANA test, should I get retested later to see if it goes away?
More ANA testing isn't suggested after a positive ANA result. Instead, your doctor may order extractable nuclear antigen (ENA) testing, which can check for specific types of autoantibodies.
What level of ANA can point to lupus?
An ANA test can't diagnose lupus. But you may have lupus if you have:
- Lupus symptoms
- A positive ANA test result
- Other positive lab tests, such as protein in your pee and low levels of platelets
Can prescription or over-the-counter medicines cause a false positive ANA?
Yes, your ANA test can still show autoantibodies even if you don't have an autoimmune condition. There are many reasons this can happen, including taking certain prescriptions or over-the-counter medications. Let your doctor know if you're taking any medications, supplements, or vitamins.
Which autoimmune diseases have a negative ANA?
Many autoimmune conditions can have a negative ANA test. About 1 out of 6 people just diagnosed with lupus get a negative ANA test. A negative ANA test just means you don't have autoantibodies yet. You may form them later if your symptoms suggest lupus, mixed connective tissue disorder, Sjogren’s disease, or scleroderma. Your doctor will match your symptoms and test for specific autoantibodies found in the other autoimmune conditions.