ANA (Antinuclear Antibody)
Antinuclear antibodies target structures inside the cell nucleus and are the standard screening test for systemic lupus erythematosus (SLE) and other connective tissue diseases. ANA is reported as a titre and a pattern (speckled, homogeneous, nucleolar, centromere). A positive ANA is sensitive but not specific — up to 15% of healthy adults, especially women over 60, are ANA-positive without disease.
Expected Result
Normal
Negative (titre <1:80)
Reported as a titre and pattern (e.g., 1:160 speckled). Most labs call 1:80 or higher positive.
This is a qualitative test — results are reported as positive or negative rather than as a numeric range. Interpretation may vary by laboratory method; always review with your doctor.
What a Negative Result Means
A negative ANA makes SLE and most connective tissue diseases very unlikely — ANA is 95%+ sensitive for SLE. A negative ANA with joint or skin symptoms shifts the focus to seronegative disease, fibromyalgia, or other causes.
What a Positive Result Means
A positive ANA is sensitive but not specific. Higher titres (1:640 and above) and certain patterns are more clinically meaningful. SLE (homogeneous or speckled), systemic sclerosis (nucleolar or centromere), Sjögren's (speckled), mixed connective tissue disease, and autoimmune hepatitis all cause positive ANA. Follow-up ENA panel, anti-dsDNA, and complement studies pin down the specific diagnosis.
Frequently Asked Questions
My ANA is positive but I feel fine. Should I worry?
Not necessarily. About 5–15% of healthy adults have positive ANA — more common in women, in older people, and after viral infections. A positive ANA without symptoms or other autoantibodies rarely becomes disease. Your doctor will assess symptoms, do a physical exam, and may order follow-up tests before deciding on further workup.
What does the ANA pattern mean?
The immunofluorescence pattern hints at the underlying antigen. Homogeneous often points to anti-dsDNA or anti-histone (SLE, drug-induced lupus). Speckled points to anti-Sm, anti-SSA/SSB, anti-RNP (SLE, Sjögren's, MCTD). Nucleolar suggests systemic sclerosis. Centromere suggests limited scleroderma/CREST. Patterns are a clue, not a diagnosis.
How high a titre is clinically important?
Titres below 1:80 are often not reported as positive. 1:80–1:160 is low-grade positivity of uncertain significance, especially in older adults. Titres 1:320 and above are more likely to reflect real autoimmune disease. The titre alone is never diagnostic — it guides the decision about further antibody testing and clinical evaluation.
Related Autoimmune tests
See all →Anti-TPO Antibody
Antibody against thyroid peroxidase — key marker of autoimmune thyroiditis.
IU/mLAutoimmuneAnti-dsDNA Antibody
Highly specific antibody for systemic lupus erythematosus (SLE).
AutoimmuneRheumatoid Factor (RF)
Antibody used in rheumatoid arthritis workup — sensitive but not specific.
AutoimmuneAnti-CCP Antibody
Highly specific rheumatoid arthritis antibody — often positive before symptoms.
This information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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