S-ANA is a blood test used in the investigation of suspected systemic autoimmune diseases. The test detects antinuclear antibodies (ANA), which are autoantibodies that react against structures within the body's own cells.
ANA may be present in conditions such as systemic lupus erythematosus (SLE), Sjögren's syndrome, systemic sclerosis, myositis, and other connective tissue diseases. However, a positive ANA result does not in itself mean that you have an autoimmune disease. ANA can also be found in people without disease, and the result should always be assessed together with symptoms, medical history, and, when available, other test results.
Antinuclear antibodies (ANA) are present in approximately 95% of people with systemic lupus erythematosus (SLE). ANA therefore plays an important role in the classification criteria used to support the assessment and classification of SLE. ANA may also be included in the investigation of other autoimmune conditions, such as autoimmune hepatitis.
What is analysed in an S-ANA test?
This test analyses antinuclear antibodies (ANA), autoantibodies directed against antigens in the cell nucleus that may be present in several different systemic autoimmune diseases.
If the ANA result is positive, the analysis may be supplemented with testing for more specific antibodies against double-stranded DNA (dsDNA) and a number of known nuclear antigens, known as extractable nuclear antigens (ENA), which may include:
- Anti-Jo-1 Anti-RNP70
- Anti-RNP70(U1)
- Anti-Scl-70
- Anti-Sm
- Anti-SSA/Ro
- Anti-SSB/La
- Anti-centromere
Which specific antibodies are analysed and reported following a positive S-ANA result depends on the outcome of the initial analysis and the laboratory's testing method.
These supplementary antibody analyses can provide additional guidance when investigating conditions such as SLE, Sjögren's disease, systemic sclerosis, myositis, and other systemic connective tissue diseases.
How will I receive my test result?
The ANA result is usually reported qualitatively, for example as:
- Negative
- Positive
- Strongly positive
If ANA is positive, the fluorescence pattern observed during the analysis may also be reported. The pattern can provide additional guidance regarding which autoantibodies may be present.
When may an ANA test be appropriate?
S-ANA is primarily used when symptoms raise suspicion of a systemic autoimmune disease, for example in cases of:
- recurrent or unexplained joint pain and joint swelling
- skin rashes or pronounced sensitivity to sunlight, dry eyes, and dry mouth
- persistent unexplained fever
- muscle weakness or muscle-related symptoms
- other symptoms that may suggest a systemic connective tissue disease
Important information
A positive ANA test is not the same as a diagnosis. ANA can also occur in some healthy individuals, particularly at lower levels, and becomes more common with increasing age. ANA may also occur temporarily in connection with certain infections without this meaning that the person has an autoimmune disease.
A negative ANA result does not rule out all autoimmune connective tissue diseases either. Certain specific autoantibodies may be present despite a negative ANA screening result.
The result should therefore always be assessed together with symptoms and other medical information.
Note! The ANA test is not a general health screening test and should only be performed when an autoimmune disease is suspected. A positive result may require further testing and medical follow-up. If you are unsure about your symptoms, you should consult a doctor.
