Metabolism USMLE Step 1 Practice Question
A 22-year-old man presents with bloating, crampy abdominal pain, and watery diarrhea 30 minutes after consuming ice cream. He reports identical symptoms with milk but tolerates meat and fruit without difficulty. Vital signs are normal (BP 118/76, HR 78, RR 14, Temp 37°C). Physical examination is unremarkable. Serum glucose is 95 mg/dL. Which enzyme deficiency best explains his symptoms?
Answer choices
- AMaltase in saliva
- BSucrase in hepatocytes
- CLactase on the intestinal brush borderCorrect answer
- DPancreatic amylase in the intestinal lumen
- ETrehalase in the stomach
- FGalactose-1-phosphate uridyltransferase in hepatocytes
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