The ANA titre measures the concentration of anti-nuclear antibodies in the blood, expressed as the highest dilution of serum at which ANA fluorescence is still detectable. It is reported as a ratio — such as 1:40, 1:80, 1:160, 1:320, or 1:640 — where higher numbers indicate greater antibody concentration and a stronger autoimmune response.
The ANA titre provides important context for interpreting a positive ANA result. Low titres (1:40 to 1:80) are common in healthy individuals and rarely indicate significant autoimmune disease. Higher titres (1:160 and above) are more clinically meaningful and, when combined with compatible symptoms and patterns, increase the likelihood of a systemic autoimmune connective tissue disease such as lupus or Sjögren's syndrome.
FAQs
What ANA titre is considered significant?
A titre of 1:160 or above is generally considered clinically significant and warrants further investigation, particularly when accompanied by compatible symptoms. Titres of 1:40 to 1:80 are common in healthy individuals and are less likely to represent true autoimmune disease.
Can my ANA titre change over time?
Yes — ANA titres can fluctuate with disease activity. They may rise during flares of autoimmune disease and fall during remission or with effective treatment. However, titres do not always mirror clinical symptoms closely, so they are one part of monitoring rather than the sole guide to treatment.
Should I be concerned about a low-positive ANA titre with no symptoms?
A low-positive ANA (1:40 to 1:80) without symptoms is very common and usually not a cause for concern. However, it is worth discussing with your doctor, as periodic follow-up may be recommended to monitor for the development of symptoms over time.
Why do ANA titres vary between laboratories?
Different laboratories use different methods, substrates, and cut-off thresholds. A titre of 1:80 at one laboratory may not be directly comparable to a titre at another. Results should ideally be compared using the same laboratory and methodology over time.
