A 31-year-old woman is evaluated in the outpatient rheumatology clinic for a 3-month history of symmetric joint pain and swelling in her wrists and metacarpophalangeal joints. She also reports profound fatigue and the recent appearance of a mildly pruritic, erythematous rash over her nose and cheeks that worsens after sun exposure. Vital signs are within normal limits. Physical examination confirms the presence of a malar rash and active synovitis in the hands. Which of the following is the most appropriate initial step in laboratory evaluation?
- Antinuclear antibody assayCevap
- BAnti-double-stranded DNA antibody assay
- CAnti-cyclic citrullinated peptide antibody assay
- DSerum complement levels
- ELupus anticoagulant assay
Cevap
Antinuclear antibody assay
The clinical presentation of a young woman with a photosensitive malar rash, symmetric polyarthritis, and fatigue is highly suspicious for systemic lupus erythematosus (SLE). The antinuclear antibody (ANA) assay is the most appropriate initial step in laboratory evaluation because it is highly sensitive (positive in >95% of patients with SLE). A negative ANA effectively rules out SLE in most cases. If the ANA is positive, more specific confirmatory testing is then indicated.
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Anahtar Kavram
The antinuclear antibody (ANA) assay is the most appropriate initial screening test for suspected systemic lupus erythematosus due to its high sensitivity.