ANA and lupus-specific antibodies vs Anti-histone drug-induced lupus antibody
How to tell ANA and lupus-specific antibodies and Anti-histone drug-induced lupus antibody apart when a board question makes them look alike.
ANA screens; anti-dsDNA nephritis/activity and anti-Smith specificity support SLE; anti-histone plus drug exposure supports drug-induced lupus.
Side by side
ANA is sensitive but nonspecific for SLE; anti-dsDNA tracks nephritis/activity; anti-Smith is specific for SLE.
Anti-histone antibodies support drug-induced lupus, especially with hydralazine, procainamide, or isoniazid exposure and usually less renal/CNS disease.
ANA is sensitive but nonspecific for SLE; anti-dsDNA tracks nephritis/activity; anti-Smith is specific for SLE.
Anti-histone antibodies support drug-induced lupus, especially with hydralazine, procainamide, or isoniazid exposure and usually less renal/CNS disease.
The repair move
Before naming the answer, force the stem through the separator: ANA screens; anti-dsDNA nephritis/activity and anti-Smith specificity support SLE; anti-histone plus drug exposure supports drug-induced lupus.
Try a free question
CoreA 28-year-old woman has a malar rash sparing the nasolabial folds, oral ulcers, photosensitivity, symmetric small joint arthritis, proteinuria 3.5 g/day with active urinary sediment, and pancytopenia. ANA is positive 1:1280 homogeneous; anti-dsDNA is positive at high titer; anti-Smith is positive; complement C3 and C4 are low. Which condition is most likely?
Show answer and explanation
Answer: A. Systemic lupus erythematosus. Systemic lupus erythematosus features ANA positive (sensitive but not specific); anti-dsDNA correlates with disease activity and lupus nephritis; anti-Smith is highly specific for SLE. Low complement (C3, C4) reflects consumption from immune complexes. Lupus nephritis is suggested by proteinuria and active urinary sediment.
Why the other choices are tempting
- B. Drug-induced lupus typically has anti-HISTONE antibodies (not anti-dsDNA or anti-Smith) and usually spares the kidneys and CNS.
- C. Rheumatoid arthritis has RF and anti-CCP, not anti-dsDNA/anti-Smith.
- D. Mixed connective tissue disease has anti-U1 RNP at high titer with overlapping features of SLE, scleroderma, polymyositis.
- E. Dermatomyositis has heliotrope rash, Gottron papules, and anti-Mi-2 or anti-Jo-1, not anti-dsDNA/anti-Smith.
Flashcards
Tap a card to flip it.
What clue supports ANA and lupus-specific antibodies?
Choose ANA and lupus-specific antibodies when the stem gives this pattern: ANA is sensitive but nonspecific for SLE; anti-dsDNA tracks nephritis/activity; anti-Smith is specific for SLE.
What clue supports Anti-histone drug-induced lupus antibody?
Choose Anti-histone drug-induced lupus antibody when the stem gives this contrasting pattern: Anti-histone antibodies support drug-induced lupus, especially with hydralazine, procainamide, or isoniazid exposure and usually less renal/CNS disease.
Quick answers
What is the fastest way to tell ANA and lupus-specific antibodies from Anti-histone drug-induced lupus antibody?
ANA screens; anti-dsDNA nephritis/activity and anti-Smith specificity support SLE; anti-histone plus drug exposure supports drug-induced lupus.
What is the key clue for ANA and lupus-specific antibodies?
ANA is sensitive but nonspecific for SLE; anti-dsDNA tracks nephritis/activity; anti-Smith is specific for SLE.
What is the key clue for Anti-histone drug-induced lupus antibody?
Anti-histone antibodies support drug-induced lupus, especially with hydralazine, procainamide, or isoniazid exposure and usually less renal/CNS disease.