A 35-year-old woman has a malar rash, arthralgia and proteinuria. Which antibody is the most specific for her likely disease?
Answer and explanation
Correct answer: D. Anti-double-stranded DNA antibody
- Step 1: The picture is systemic lupus erythematosus with lupus nephritis. Step 2. Antinuclear antibody is the most sensitive test, but anti-dsDNA and anti-Smith antibodies are the most specific. Answer: anti-double-stranded DNA antibody. Why not the others: antinuclear antibody is sensitive but not specific, anti-histone antibodies indicate drug-induced lupus and rheumatoid factor suggests rheumatoid arthritis.
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