Questions and Answers
Which enzyme is associated with pyruvate dehydrogenase in the conversion of pyruvate to acetyl-CoA?
What is the primary central nervous system manifestation of thiamine deficiency?
What combination of symptoms signifies Wernicke-Korsakoff syndrome?
Which part of the brain is primarily noted for atrophy in thiamine deficiency pathologies on MRI?
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What must be administered before glucose to patients with suspected thiamine deficiency?
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Which metabolic pathway is associated with transketolase and thiamine?
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What is the likely diagnosis for the homeless man with a history of alcoholism and the presented symptoms?
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Which clinical manifestation is associated with wet beriberi?
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What does thiamine act as a cofactor for?
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What symptom would not typically indicate vitamin B12 deficiency?
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How does dry beriberi primarily present in patients?
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What is a notable effect of arsenic poisoning relating to thiamine?
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Which enzyme is not associated with thiamine deficiency?
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What laboratory finding is most characteristic of vitamin B1 deficiency?
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Study Notes
Thiamine Deficiency
- A 36-year-old homeless man presents with shortness of breath, tingling and burning in his legs, and decreased sensation in his feet due to thiamine deficiency.
- The patient has an extensive history of alcoholism, which can lead to thiamine deficiency.
- Physical examination reveals tachycardia, bilateral rales, and bilateral pitting edema.
- An x-ray of the chest shows an enlarged cardiac silhouette and bilateral pulmonary congestion.
Beriberi
- The patient has symptoms of both wet and dry beriberi.
- Wet beriberi presents with high-output congestive heart failure and dilated cardiomyopathy.
- Dry beriberi presents with peripheral neuropathy, muscular atrophy, and diminished sensation and reflexes.
Thiamine as a Cofactor
- Thiamine is part of thiamine pyrophosphate (TPP), which acts as a cofactor for three enzymes:
- Transketolase (in the hexose monophosphate shunt)
- Pyruvate decarboxylase (in the pyruvate dehydrogenase complex)
- α-ketoglutarate decarboxylase (in the α-ketoglutarate dehydrogenase complex)
Other Pathologies
- Wernicke encephalopathy is the central nervous system manifestation of thiamine deficiency.
- Wernicke encephalopathy consists of nystagmus, ophthalmoplegia, and cerebellar ataxia.
- Wernicke-Korsakoff syndrome is the combination of Wernicke encephalopathy and symptoms of confusion, psychosis, and confabulation.
- It is standard practice to give thiamine before glucose to any patient with suspected thiamine deficiency to prevent Wernicke-Korsakoff syndrome.
MRI Findings
- Atrophy of the mammillary bodies is the most commonly noted finding.
- Degenerative changes may be seen in the cerebellum, brain stem, and diencephalon.
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Description
A homeless man presents with shortness of breath, tingling in his legs, and other symptoms. Analyze the physical examination results to diagnose his condition.
