Metabolism USMLE Step 1 Practice Question
A 3 year old boy is brought to the clinic because of abdominal pain, constipation, and decreased energy. His family recently moved into an older home that is undergoing renovation. Examination shows mild developmental delay. Laboratory studies reveal microcytic anemia and basophilic stippling. Lead toxicity most directly inhibits which of the following enzymes?
Answer choices
- AALA dehydratase and ferrochelataseCorrect answer
- BUroporphyrinogen decarboxylase and ferrochelatase
- CBiliverdin reductase and heme oxygenase
- DALA synthase and heme oxygenase
- EPorphobilinogen deaminase and ALA synthase
- FCytochrome P450 and delta-aminolevulinic acid synthase
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