What Does an ANA Test Show?

Why this matters

ANA is one of the most common tests requested when someone has symptoms such as joint pain, rashes, fatigue or dry eyes and mouth. It is also one of the most commonly misunderstood. Knowing what a result does and does not mean can take a lot of worry out of the wait for an appointment.

What ANA actually measures

Antibodies are proteins the immune system makes to recognise and fight germs such as bacteria and viruses. Antinuclear antibodies (ANA) are antibodies that instead target material inside the nucleus, the control centre of the body's own cells. Most people make small amounts, but higher levels can be a sign of an autoimmune condition, where the immune system attacks the body's own tissues.

In most laboratories the test is done by adding a diluted sample of blood to cells on a glass slide. A dye is added that makes any ANA glow under a special microscope. The result is usually reported in two parts: a titre and a pattern.

Titre and pattern

The titre shows how far the blood could be diluted and still give a positive result. It is written as a ratio: 1:80 means one part blood to 80 parts liquid, and 1:640 means one part to 640. Antibodies still found at 1:640 are at a much higher level than those found only at 1:80. Higher titres are more likely to matter for your health.

The pattern describes how the glow looks on the cells, for example evenly spread (homogeneous), spotty (speckled), or concentrated in particular parts of the nucleus (nucleolar or centromere). Different patterns are linked with different conditions, which helps clinicians decide which follow-up tests to request.

A positive result is not a diagnosis

A low positive ANA is found in a significant minority of healthy people, and becomes more common with age, in women, during some infections and with certain medicines. On its own it does not mean you have an autoimmune condition.

ANA is most useful in two ways. A clearly positive result alongside relevant symptoms supports further investigation for conditions such as lupus, Sjögren's disease, systemic sclerosis and mixed connective tissue disease. These are long-term autoimmune conditions that can affect the joints, skin, glands and other organs. A negative result makes some of these conditions, particularly lupus, much less likely.

What usually happens next

If your ANA is positive and you have symptoms, your clinician may request more specific tests. These often include an ENA test (extractable nuclear antigen antibodies), which checks for particular types of ANA, named Ro, La, Sm and RNP, that are linked with specific conditions. Another common test is anti-dsDNA, which looks for antibodies against the body's own DNA and is linked with lupus. Complement (C3 and C4), proteins that help the immune system and can fall when lupus is active, and general blood tests for inflammation such as CRP may also be checked. Your GP may refer you to a rheumatologist, a specialist in joint and autoimmune conditions, if the results and symptoms together suggest it.

What you could do

Keeping a clear record of symptoms makes an ANA result much easier to interpret.

• Note when symptoms started, how often they happen and anything that seems to trigger them, such as sunlight or stress
• Ask for your titre and pattern, not just whether the result was positive or negative
• If a low positive result was found and you feel well, ask your GP whether any follow-up is needed rather than assuming the worst

This article is for general information only and is not a substitute for medical advice. If you are worried about your health or your results, speak to your GP or specialist team. In an emergency, call 999 or go to A&E.

References:

NHS, 'Lupus' https://www.nhs.uk/conditions/lupus/

NICE, 'Rheumatoid arthritis in adults: management' (NG100) https://www.nice.org.uk/guidance/ng100