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Lupus nephritis — USMLE Step 2 CK MCQ

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EasyInternal MedicineLupus nephritisUSMLE Step 2 CK

A 42-year-old Asian American man comes to the clinic because of progressive symptoms. History and focused examination are notable for malar rash, arthritis, low complement, hematuria, and red blood cell casts. Temperature is 98.6°F (37.0°C), blood pressure is 126/78 mmHg, pulse is 84/min, respirations are 16/min, and oxygen saturation is 98% on room air. Physical examination confirms the key finding and shows no unrelated abnormality that would better explain the presentation. Laboratory studies show creatinine 2.1 mg/dL, BUN 34 mg/dL, and urinalysis findings consistent with the presentation. Which of the following is the most appropriate initial diagnostic study?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Renal biopsy

The vignette describes Lupus nephritis, supported by malar rash, arthritis, low complement, hematuria, and red blood cell casts. Renal biopsy is the single best answer because it matches the diagnostic or management priority in this clinical setting. The other choices are plausible alternatives in related presentations, but they do not best fit the timing, findings, and guideline-directed approach described here.

Reference: American College of Rheumatology 2024 Lupus Nephritis Guideline