ANA test explained: antinuclear antibodies

Antinuclear antibodies (ANA) are autoantibodies that the immune system mistakenly produces against components of its own cells' nuclei, for example DNA or nuclear proteins. A healthy person's immune system usually does not produce them, or the amount is very small. The ANA test is done by immunofluorescence, and the result is given as a titre — the blood dilution ratio at which the antibodies can still be detected (e.g. 1:80, 1:160, 1:320). The larger the second number, the more antibodies there are in the blood. Alongside the titre, the fluorescence pattern is often reported too (homogeneous, speckled, centromere and others), which helps to suspect a particular disease. ANA is a sensitive but non-specific test — a positive result is not in itself a diagnosis, it only shows that it is worth looking for signs of an autoimmune process together with other tests (anti-dsDNA, rheumatoid factor, anti-CCP) and clinical symptoms.

• When there is joint pain, stiffness or swelling of unclear origin
• When there is long-lasting tiredness together with fever with no clear cause
• When a rash, changes in skin colour or enlarged lymph nodes appear
• When systemic lupus erythematosus or another connective tissue disease is suspected
• When there is muscle or abdominal pain with no clear cause
• As an additional test if there are autoimmune diseases in the family

A positive ANA is considered raised according to MedlinePlus and may point to an autoimmune disease, but on its own it does not confirm a diagnosis — in some healthy people, especially older ones, ANA can also be positive without any disease.

What can lie behind a positive result

• Systemic lupus erythematosus (SLE) — the most common cause when ANA is positive together with typical symptoms
• Other autoimmune diseases — systemic sclerosis, Sjögren's syndrome, mixed connective tissue disease, autoimmune hepatitis, rheumatoid arthritis, thyroid diseases
• Drug-induced lupus
• Viral infections
• Cancers, lymphomas
• The natural effect of age — in some healthy people the ANA titre rises with age

Symptoms that can accompany a positive result

• Fever
• A rash, blisters or changes in skin colour
• Tiredness
• Joint pain, stiffness and swelling
• Muscle pain
• Enlarged lymph nodes
• Abdominal pain

What to discuss with a doctor

• Further autoantibody tests (anti-dsDNA, anti-CCP, rheumatoid factor) for more precise diagnosis
• Assessment of the fluorescence pattern (homogeneous, speckled, centromere) — it helps to suspect a particular disease
• Discussing symptoms and the clinical picture with a doctor, since a positive ANA alone does not confirm a diagnosis
• Reviewing the medicines you take with your doctor, if drug-induced lupus is suspected
• Repeating the test later if symptoms persist

What the fluorescence pattern means

Alongside the titre, the laboratory often reports a fluorescence pattern — for example homogeneous, speckled or centromere. This pattern helps the doctor narrow down the list of possible autoimmune diseases, but it does not establish a diagnosis on its own.