A 32-year-old woman comes to the ambulatory care center reporting profound fatigue and achiness in her wrists and hands over the past 3 months. She also notes a facial rash that becomes more prominent after spending time outdoors in the sun. On physical examination, there is a fixed erythema over the malar eminences and the bridge of the nose; the nasolabial folds are unaffected. Examination of the oral cavity reveals two painless ulcerations on the hard palate. A dipstick urinalysis in the clinic shows 2+ proteinuria and hematuria. Which of the following is the most appropriate initial laboratory test to evaluate this patient's condition?
- Antinuclear antibodyCevap
- BAnti-double-stranded DNA antibody
- CAnti-cyclic citrullinated peptide antibody
- DSerum complement levels (C3, C4)
- ERenal ultrasonography with biopsy
Cevap
Antinuclear antibody (ANA) testing is the most appropriate initial step.
The correct answer is the antinuclear antibody (ANA) test. This patient's classic presentation of a photosensitive malar rash, oral ulcers, inflammatory arthritis, and signs of nephritis is highly suspicious for systemic lupus erythematosus (SLE). Because SLE can involve nearly any organ system, establishing the diagnosis requires a combination of clinical criteria and serologic evidence. The most appropriate initial laboratory test is the ANA test because it has a very high sensitivity (>95%) for SLE. A negative ANA test effectively rules out the disease in most cases.
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Anahtar Kavram
The antinuclear antibody (ANA) test is the most appropriate initial screening test for suspected systemic lupus erythematosus (SLE) due to its high sensitivity.