Metabolism USMLE Step 1 Practice Question
A 37-year-old man presents with vomiting, watery diarrhea, and confusion 6 hours after ingesting contaminated herbal supplements. Vital signs show BP 102/68, HR 108, RR 20, temp 37.2°C. He has characteristic garlic odor on breath and denies recent medication use. ECG demonstrates prolonged QT interval. Serum arsenic level is markedly elevated at 45 μg/L (normal <15). Which cofactor is most directly inhibited by this toxin?
Answer choices
- ATetrahydrobiopterin
- BPyridoxal phosphate
- CCobalamin
- DLipoic acidCorrect answer
- EBiotin
- FThiamine pyrophosphate
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