Diseases That Can Cause a Positive ANA Test - GoodRx (2024)

Positive test results can be scary — especially when you aren’t sure what they mean. The good news? Positive test results don’t always mean that something is wrong. No test is perfect. The information they provide isn’t always black and white.

Since tests aren’t perfect, positive results always need to be “interpreted clinically.” In other words, your healthcare professional will need to look at the bigger picture — your symptoms, physical exam findings, and test results — in order to determine if results are meaningful or not.

This is especially true when it comes to the antinuclear antibody (ANA) test. Positive ANA tests are common —even in healthy people — and they have many different causes. We’re here to shed some light on it all.

What is an ANA test?

In order to understand ANA tests, we need to understand a bit about cells and antibodies first.

Cells are the tiny building blocks that make up the body. Most cells have a nucleus at their center. The nucleus serves as the control center for the cell — it stores your DNA and regulates the activities of the cell. The letter “N” in ANA stands for “nuclear,” which refers to the nucleus of cells.

Antibodies are proteins made by your body’s immune system. They’re designed to attack foreign substances like viruses and bacteria. But sometimes the body accidentally creates antibodies for parts of your body that aren’t foreign. These are called “autoantibodies” because “auto” means “self.”

A positive ANA is an autoantibody to a protein in the nucleus of your cells. Autoantibodies may sometimes lead to autoimmune disease, but not always.

What do ANA test results look like?

ANA tests look for antinuclear antibodies in your blood. The results are reported as ratios called “titers.” These titers look at how much a blood sample can be diluted and still test positive for the antibodies. The higher the number (or the more a sample is diluted), the more ANA is present.

The lowest possible titer is a ratio of 1:40 (or 1 part blood to 40 parts of saline). After that, the numbers double as the blood sample is further diluted: 1:80, 1:160, 1:320, and so on. Most labs and rheumatologists only consider titers of 1:80 or higher as potentially significant since titers of 1:40 are so common (more on this below).

How common are positive ANA tests?

Positive ANA test results are common. About 15% of healthy folks in the U.S. have an ANA titer of 1:80 or higher. This percentage is even higher for ANA titers of only 1:40, which is why they’re considered insignificant. This means that over 50 million people living in the U.S. alone have positive ANA test results.

Of note, it’s a common misconception that a positive ANA test diagnoses lupus — an autoimmune disease that can cause many of the symptoms listed below. But of the more than 50 million people in the U.S. with positive ANA tests, only 1.5 million are living with lupus. So, that math doesn’t quite add up. Keep reading to understand why.

When might a healthcare professional order an ANA test?

Positive ANA test results are a lot more meaningful if you also have symptoms of an autoimmune condition. Symptoms like these could raise concern for an autoimmune condition, and might warrant ANA testing:

• Painful, swollen joints

• Rashes

• Sores inside your mouth or nose

• Hair loss, especially near your temples

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• White/purple color changes in your fingers when exposed to cold (Raynaud’s)

• Muscle weakness that makes it hard to walk upstairs or hold your arms over your head

• Low blood counts

• Fluid or inflammation around your heart or lungs

• Severe dry eye requiring eye drops multiple times a day, or feeling a constant sandy/gravel feeling in the eyes

• Severe dry mouth such that you can’t eat a salty cracker without a glass of water to help

• Abnormal urine tests (urinalysis)

Fatigue alone isn’t a great reason to order an ANA test. That’s because fatigue is common and has many different potential causes. But if fatigue is accompanied by any of the symptoms above, ordering an ANA test might be helpful.

What could a positive ANA test mean?

A positive ANA test could mean absolutely nothing, or it could mean something. Most healthy people make autoantibodies of some sort. When it comes to ANAs, there seems to be a strong link with age and gender. Healthy people are more likely to make ANAs as they get older. And women are more likely to make ANAs than men. The reason for this isn’t entirely clear.

So the meaning of a positive ANA test depends on why the test was sent and what symptoms are present. Ultimately, you and your healthcare professional will determine if the positive ANA test is concerning or not. If your healthcare professional isn’t sure, they may refer you to an autoimmune disease specialist (like a rheumatologist) for help.

Common causes of positive ANA tests include, but aren’t limited to:

• Infections (like Hepatitis C, human immunodeficiency virus (HIV), or even the common cold)

• Cancer

• Hypothyroidism and hyperthyroidism

• Medications (like hydralazine and many others)

• Autoimmune conditions (like lupus, multiple sclerosis, rheumatoid arthritis, and many others)

• Fibromyalgia

• No specific reason (remember, 15% of healthy people have positive ANAs)

Can ANA tests be used to ‘screen’ for autoimmune conditions before developing them?

No. Unfortunately, there’s no test that is able to do this just yet. Each autoimmune condition has its own set of symptoms, and symptoms are required for diagnosis (not just positive tests).

Of note, a negative ANA test does indeed rule out lupus. But it doesn’t mean that other autoimmune conditions aren’t possible. People with autoimmune conditions may still have negative ANAs.

If my ANA titer is very high, does that increase the chances of having autoimmune disease?

Maybe. A higher ANA titer does seem to increase the chances of having or developing an autoimmune disease. One study found that people who had ANA titers greater than 1:640 were more likely to be diagnosed with an autoimmune disorder within the next 6 months. But even a high ANA level can’t be used to diagnose an autoimmune disease. This same study found that some healthy people had high ANA levels and no autoimmune issues. So, if the symptoms don’t fit, a higher titer ANA still doesn’t mean much.

What should you do next if you have a positive ANA test?

First, take a deep breath. A positive ANA test doesn’t automatically mean that you have an autoimmune condition — or any type of medical condition for that matter. Next, talk to your healthcare professional about your symptoms. Together, you’ll decide on next best steps, like a referral to a specialist or more testing.