Toxicology USMLE Step 1 Practice Question
A 5-year-old boy from an older home with peeling paint presents with developmental delay, abdominal pain, and constipation. Vital signs: BP 102/68 mmHg, HR 98/min, RR 20/min, temp 37°C. Blood smear reveals microcytic anemia with basophilic stippling. Laboratory studies show blood lead level 72 mcg/dL (markedly elevated), hemoglobin 9.2 g/dL, and normal reticulocyte count. No fever or recent infections noted. Which mechanism best explains this patient's anemia?
Answer choices
- ADefective spectrin anchoring to the membrane
- BInhibition of ferrochelatase and ALA dehydrataseCorrect answer
- COxidation of hemoglobin iron to Fe3+
- DAutoimmune destruction of red blood cells by IgG
- EDecreased erythropoietin production by the kidney
- FGlucose-6-phosphate dehydrogenase deficiency
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.