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MBBS QUESTION #10329
Question 1
A patient with chronic alcoholism presents with confusion, ataxia, and ophthalmoplegia (Wernicke's encephalopathy). This results from deficiency of which vitamin, and why can administering glucose without concurrent vitamin replacement be dangerous?
  • Vitamin B1 (thiamine); glucose metabolism consumes thiamine as a required cofactor for pyruvate dehydrogenase and related enzymes, potentially precipitating or worsening Wernicke's encephalopathy in a thiamine-depleted patient✔️
  • Vitamin B12; glucose administration has no relevant interaction with B12 stores
  • Vitamin C; glucose rapidly depletes remaining vitamin C reserves
  • Vitamin D; glucose administration has no relevant interaction with vitamin D
Correct Answer Explanation
Thiamine (vitamin B1) is an essential cofactor for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and transketolase; administering glucose to a thiamine-deficient patient increases demand on these thiamine-dependent enzymes, which can acutely worsen or unmask Wernicke's encephalopathy — hence the practice of giving thiamine before or with glucose in at-risk patients.