What does the Antinuclear Antibody Titre test measure?

Why is Antinuclear Antibody Titre measured?

ANA screening is the gateway test for systemic lupus erythematosus, Sjögren syndrome, systemic sclerosis, mixed connective tissue disease, and drug-induced lupus. A positive ANA prompts reflex testing for specific autoantibodies that define disease subsets and guide prognosis. Sensitivity for SLE exceeds 95 per cent, but specificity is lower because low-titre ANA occurs in healthy individuals, infection, malignancy, and other inflammatory states.

Reference ranges

Standard reference

Negative at 1:40 dilution; titres ≥1:80 are considered positive and clinically relevant when correlated with symptoms.

Functional medicine optimal

Negative. Titre magnitude alone does not diagnose or exclude disease and must be interpreted with pattern and specific antibody results.

Units

titre, ratio (e.g., 1:80, 1:160, 1:320)

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.