American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the best way to confirm a flare of systemic lupus erythematosus?

1. Anti-nuclear antibody test

2. Anti-double-stranded DNA antibody measurement

3. Complement levels

4. ESR test

The correct answer is: Anti-double-stranded DNA antibody measurement

The measurement of anti-double-stranded DNA antibodies is considered the best way to confirm a flare of systemic lupus erythematosus (SLE). This is because these antibodies are specific to SLE and their levels correlate closely with disease activity. During a flare, there is often an increase in the concentration of these antibodies, making them a useful marker to assess the severity and activity of the disease. In contrast, while the anti-nuclear antibody test can be positive in SLE patients, it is not specific to the disease and can be found in various other autoimmune conditions. Complement levels can be useful, as they may decrease during disease flares due to complement consumption, but they do not directly confirm a flare in the same way that anti-dsDNA levels do. The erythrocyte sedimentation rate (ESR) test can indicate inflammation but is non-specific and can be influenced by various factors unrelated to SLE activity. Therefore, measuring anti-double-stranded DNA antibodies provides the most specific insight into disease activity in SLE.