Micro & Immunology · single question
A patient with positive ANA (antinuclear antibodies) — what type of disease characteristic is this?
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Correct answer: B. Autoimmune disease
- A. Infections do not typically produce positive ANA — ANA is a marker of autoimmunity.
- B. Positive ANA (antinuclear antibodies) is the hallmark laboratory finding of AUTOIMMUNE diseases, particularly SLE. ANA tests detect antibodies against nuclear components (dsDNA, histones, Smith antigen, Ro/SSA, La/SSB). ANA is positive in >95% of SLE patients. The specific ANA pattern and titer help differentiate between different autoimmune conditions.
- C. Genetic disorders (Down syndrome, cystic fibrosis) are caused by chromosomal or gene mutations — they are not characterized by positive ANA.
- D. Metabolic disorders (diabetes, gout) do not produce positive ANA.
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