Metabolism USMLE Step 1 Practice Question
A 7-month-old boy presents with failure to thrive and pallor. Vital signs show HR 128/min, RR 22/min, Temp 37.2°C. Laboratory studies reveal hemoglobin 7.2 g/dL with megaloblastic anemia unresponsive to folate and vitamin B12 supplementation. Markedly elevated urinary orotic acid is noted, while serum ammonia remains normal at 18 μmol/L. The patient denies hepatomegaly on examination. Which of the following is the most appropriate treatment?
Answer choices
- AThiamine supplementation
- BRestriction of dietary protein
- CAllopurinol
- DUridine supplementationCorrect answer
- EVitamin C supplementation
- FCarnitine supplementation
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