What is ANA?
ANA (antinuclear antibodies) are seen in systemic autoimmune diseases. The laboratory reports the quantity of ANA as a titre (the higher the titre the more times the sample can be diluted and ANA still be detected) 1:80 is a low titre, 1:160 is a high titre. The pattern of staining is also reported (eg homogenous, speckled, centromere patterns) as this may guide further tests that are associated with particular conditions
When should ANA be requested?
ANA are commonly seen in normal, healthy individuals, particularly at low titre. ANA may also be present if the patient has an infection. It is therefore only useful to request an ANA if the patient has clear clinical features suggestive of a systemic autoimmune disease for example systemic lupus erythematosus (SLE) (eg, photosensitivity, pleurisy), systemic sclerosis (eg, Raynaud phenomenon, skin changes), or Sjögren’s syndrome (eg, unexplained dry eyes, dry mouth).
The higher the clinical probability that the patient has a systemic autoimmune disease, the more likely the results of an ANA will help with diagnosis. If ANA is requested when there is a low clinical probability of systemic autoimmune disease it is likely that the result will be falsely positive and hinder rather than help the diagnostic process.
When should ANA be repeated?
ANA titres are not helpful in monitoring of patients diagnosed with ANA-associated autoimmune disease. Repeat testing is NOT recommended unless there is a significant change in the patient’s clinical presentation.