Antinuclear antibodies (ANA): what they are, what they tell you and when they’re tested

Antinuclear antibodies, or ANA, are antibodies that recognise parts of the nucleus of your own cells. Doctors look for them when they suspect an autoimmune condition such as lupus. But a positive ANA is common in people who are well too.

When they’re tested

Doctors order them when you have symptoms that suggest an autoimmune condition: painful, swollen joints, a red rash on the face that gets worse in the sun, fingers that turn white in the cold, very dry eyes and mouth, or a fever with no clear cause.

It is not a test to have without symptoms. Many healthy people have a positive ANA, and a positive result with no symptoms often brings only worry and more tests.

That is why Rosa does not test them. Instead it looks at high-sensitivity CRP for inflammation, your blood count, which in some autoimmune conditions shows low white cells or platelets, and a urine test.

What they tell you, and what they do not

If they are negative, a condition such as lupus is very unlikely. That is their most useful job: they help rule it out.

If they are positive, it does not mean you have a disease. What counts is how high they are, the pattern they make under the microscope and above all your symptoms. Your doctor usually then asks for more precise tests, such as anti-DNA or ENA.

ANA alone do not tell you which condition is present, or how active it is.

That is why they are read together with other tests:

• Complement C3 and C4: It falls when lupus is active
• High-sensitivity CRP: It shows whether there is inflammation
• White blood cells: They can be low in lupus
• Urine test: It shows whether your kidneys leak protein or blood

How to read the titre and pattern

The lab dilutes your blood several times and checks up to which dilution the antibodies can still be seen. The titre is that dilution: 1:80, 1:160, 1:320 and so on. The higher the second number, the more antibodies there are.

Each lab chooses the titre from which it calls them positive, often 1:80 or 1:160. Among healthy people, about one in three is positive at 1:40, more than one in ten at 1:80 and about one in twenty at 1:160. They are more common in women and with age.

The pattern is the picture they make on the nucleus: for example homogeneous, speckled, nucleolar or centromere. It helps your doctor decide which tests come next.

If your ANA is positive or negative

• Positive ANA: Often it means nothing, especially at a low titre and with no symptoms. It matters if you have symptoms.
• Negative ANA: It makes a condition such as lupus very unlikely. Other autoimmune conditions remain possible.

Why ANA can be positive

The most common causes come first.

• No disease at all: The most frequent cause, especially at a low titre, in women and with age.
• Thyroid conditions: Autoimmune thyroiditis often comes with a positive ANA.
• Infections: After some viral infections they can turn positive for a while.
• Some medicines: Certain medicines for blood pressure, the heart or inflammation can bring them on. Do not stop them on your own: talk to your doctor.
• Autoimmune conditions: Lupus, Sjögren’s syndrome, scleroderma, autoimmune hepatitis and others. The titre is usually higher and there are symptoms.

What to know before reading them

A few things change the result without changing your health.

• The method: The classic test uses a microscope. Some labs use automated methods that give slightly different results.
• The lab: The titre from which a result counts as positive differs between labs. Compare results from the same place.
• A titre that moves: Going from 1:80 to 1:160 between two tests is common and usually does not mean anything is getting worse.
• Age: Over the years they turn positive more often, even without disease.

When to worry

Talk to your doctor if:

• Your ANA is positive and you have painful, swollen joints, skin rashes, fingers that turn white in the cold or fever for no reason.
• The titre is high, for example 1:320 or more, even if you feel well: your doctor decides whether more tests are needed.
• You have foamy urine, swollen legs or blood in your urine.
• You have chest pain, sudden breathlessness or a severe headache with confusion: call 112 or go to the emergency department.

Frequently asked questions

Positive ANA at 1:160: should I worry? Not necessarily. About one healthy person in twenty has a positive ANA at 1:160. What counts is whether you have symptoms and what the other tests show. Your doctor tells you whether to look further.

What does a low-titre positive ANA, 1:80, mean? With no symptoms, usually nothing. More than one healthy person in ten has a positive ANA at 1:80.

What does a speckled pattern mean? It is one of the most common patterns. On its own it does not point to a particular condition. If the titre is high or you have symptoms, your doctor asks for ENA to see which antibodies are there.

Does a positive ANA mean lupus? No. Almost everyone with lupus has a positive ANA, but most people with a positive ANA do not have lupus. A diagnosis needs symptoms and other tests.

Does Rosa test antinuclear antibodies? No. Rosa measures high-sensitivity CRP, your blood count and a urine test, which give useful signals about inflammation, blood and kidneys. If your doctor wants ANA, they order it separately.

Sources

• Tan and colleagues, range of antinuclear antibodies in healthy individuals. Arthritis and Rheumatism, 1997. PMID 9324014
• Satoh and colleagues, prevalence and sociodemographic correlates of antinuclear antibodies in the United States. Arthritis and Rheumatism, 2012. PMID 22237992
• Aringer and colleagues, 2019 EULAR/ACR classification criteria for systemic lupus erythematosus. Annals of the Rheumatic Diseases, 2019. PMID 31383717