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Lead poisoning — USMLE Step 2 CK MCQ

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HardPediatricsLead poisoningUSMLE Step 2 CK

A 3-year-old Middle Eastern boy comes to the emergency department because of new symptoms noticed by a caregiver. History and focused examination are notable for developmental delay, abdominal pain, microcytic anemia, and old housing exposure. Temperature is 100.6°F (38.1°C), blood pressure is age appropriate, pulse is 128/min, respirations are 32/min, and oxygen saturation is 96% on room air. Physical examination confirms the key finding and shows no unrelated abnormality that would better explain the presentation. Growth parameters, hydration status, and focused testing are consistent with the described pediatric presentation. Which of the following is the most likely cause of this patient's condition?

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Correct answer: D — Inhibition of heme synthesis enzymes

The vignette describes Lead poisoning, supported by developmental delay, abdominal pain, microcytic anemia, and old housing exposure. Inhibition of heme synthesis enzymes 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: https://www.cdc.gov/#stage-9-order-96