An antinuclear antibody test shows a homogeneous pattern at a high titer. Which follow- up test is most useful to support a diagnosis of systemic lupus erythematosus?
1Rheumatoid factor
2Anti-mitochondrial antibody
3Anti-double-stranded DNA✓ 정답
4Cold agglutinin titer
해설
The antinuclear antibody test is a screening assay with limited specificity. Antibody to double-stranded DNA is highly specific for systemic lupus erythematosus and is used as a confirmatory test. Antimitochondrial antibody is associated with a different disease group.