Podcast
Questions and Answers
In a patient presenting with unexplained neurological symptoms, which metabolic defect would raise suspicion for thiamine deficiency impacting ATP production and potentially leading to neuronal injury?
In a patient presenting with unexplained neurological symptoms, which metabolic defect would raise suspicion for thiamine deficiency impacting ATP production and potentially leading to neuronal injury?
- Elevated levels of branched-chain amino acids, indicative of impaired alpha-keto acid dehydrogenase activity.
- Increased activity of the urea cycle enzymes, leading to hyperammonemia.
- Reduced activity of transketolase and pyruvate dehydrogenase, impairing glucose metabolism. (correct)
- Decreased synthesis of succinyl-CoA, affecting heme production and oxygen transport.
A patient with a history of chronic alcoholism presents with nystagmus, ataxia, and significant memory deficits including confabulation. MRI reveals atrophy of the mammillary bodies. Which of the following is the most likely underlying vitamin deficiency and associated condition?
A patient with a history of chronic alcoholism presents with nystagmus, ataxia, and significant memory deficits including confabulation. MRI reveals atrophy of the mammillary bodies. Which of the following is the most likely underlying vitamin deficiency and associated condition?
- Vitamin B1 (Thiamine) deficiency leading to Wernicke-Korsakoff syndrome (correct)
- Vitamin B3 (Niacin) deficiency leading to pellagra
- Vitamin B12 (Cobalamin) deficiency leading to pernicious anemia
- Vitamin B6 (Pyridoxine) deficiency leading to sideroblastic anemia
A researcher is investigating the pathogenesis of pellagra in a population with high corn consumption, but without the typical triad of dermatitis, diarrhea, and dementia. Which of the following interventions would most directly address the underlying metabolic defect?
A researcher is investigating the pathogenesis of pellagra in a population with high corn consumption, but without the typical triad of dermatitis, diarrhea, and dementia. Which of the following interventions would most directly address the underlying metabolic defect?
- Dietary restriction of corn products to reduce phytic acid intake.
- Supplementation with niacin or tryptophan to bypass the metabolic block. (correct)
- Supplementation with tryptophan to enhance serotonin production.
- Administration of corticosteroids to reduce skin inflammation.
A patient on long-term isoniazid therapy for tuberculosis develops peripheral neuropathy and sideroblastic anemia. Which of the following mechanisms by which isoniazid induces these effects is most likely?
A patient on long-term isoniazid therapy for tuberculosis develops peripheral neuropathy and sideroblastic anemia. Which of the following mechanisms by which isoniazid induces these effects is most likely?
A patient presents with fatigue, dermatitis, and stomatitis after prolonged treatment with a drug that inhibits the enzyme dihydrofolate reductase. Which of the following vitamin deficiencies is most likely contributing to these symptoms?
A patient presents with fatigue, dermatitis, and stomatitis after prolonged treatment with a drug that inhibits the enzyme dihydrofolate reductase. Which of the following vitamin deficiencies is most likely contributing to these symptoms?
A researcher is studying the effects of vitamin deficiencies on neurotransmitter synthesis. Which vitamin is most directly involved in the decarboxylation reactions necessary for the production of GABA, dopamine, and serotonin?
A researcher is studying the effects of vitamin deficiencies on neurotransmitter synthesis. Which vitamin is most directly involved in the decarboxylation reactions necessary for the production of GABA, dopamine, and serotonin?
A patient presents with symptoms of pellagra, but also exhibits signs of a neuroendocrine tumor. Which of the following metabolic abnormalities is the most likely cause of niacin deficiency in this patient?
A patient presents with symptoms of pellagra, but also exhibits signs of a neuroendocrine tumor. Which of the following metabolic abnormalities is the most likely cause of niacin deficiency in this patient?
A cardiologist is considering prescribing high-dose niacin to a patient with hyperlipidemia. Which of the following potential side effects is most directly related to niacin-induced prostaglandin release?
A cardiologist is considering prescribing high-dose niacin to a patient with hyperlipidemia. Which of the following potential side effects is most directly related to niacin-induced prostaglandin release?
In the context of thiamine deficiency, which of the following best describes the mechanism leading to neuronal cell death?
In the context of thiamine deficiency, which of the following best describes the mechanism leading to neuronal cell death?
Which metabolic process would be most affected by a deficiency in pyridoxine (Vitamin B6)?
Which metabolic process would be most affected by a deficiency in pyridoxine (Vitamin B6)?
Flashcards
Water-Soluble Vitamins
Water-Soluble Vitamins
Crucial for energy metabolism, amino acid, lipid, glucose metabolism, red blood cell & neurodevelopment, and collagen synthesis.
Vitamin B1 (Thiamine)
Vitamin B1 (Thiamine)
Functions as a coenzyme in the citric acid cycle and pentose phosphate pathway. Supports glutamate metabolism & myelin production.
Beriberi & Wernicke-Korsakoff Syndrome
Beriberi & Wernicke-Korsakoff Syndrome
Peripheral neuropathy (dry) or dilated cardiomyopathy (wet). Affectations of the mammillary bodies.
Vitamin B3 (Niacin)
Vitamin B3 (Niacin)
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Niacin Deficiency Causes
Niacin Deficiency Causes
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Pellagra
Pellagra
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Vitamin B6 (Pyridoxine)
Vitamin B6 (Pyridoxine)
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Vitamin B6 Deficiency Causes
Vitamin B6 Deficiency Causes
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Vitamin B6 Deficiency Symptoms
Vitamin B6 Deficiency Symptoms
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Ring Sideroblasts
Ring Sideroblasts
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Study Notes
- Focus on water-soluble vitamin disorders, particularly deficiencies and potential toxicities
- Water-soluble vitamins support several biochemical functions.
- Key functions include energy, amino acid, lipid, and glucose metabolism
- Folic acid and cobalamin are crucial for red blood cell and neurodevelopment
- Collagen synthesis relies on vitamin C (ascorbic acid)
Thiamine (Vitamin B1)
- Critical to the citric acid cycle and the pentose phosphate pathway
- Coenzyme form is thiamine pyrophosphate (TPP)
- Essential for glutamate metabolism and myelin production
- Deficiency causes include poor diet and alcohol consumption
- Deficiency leads to Beriberi and Wernicke-Korsakoff Syndrome
- Beriberi symptoms are peripheral neuropathy (dry) and dilated cardiomyopathy (wet)
- Wernicke-Korsakoff Syndrome initially affects the mammillary bodies
- Manifests as nystagmus, ataxia, psychosis, confabulations, and memory issues
- Thiamine deficiency impairs enzyme activities in the CNS and PNS
- Transketolase deficiency disrupts glucose metabolism and energy production
- Neuronal dysfunction, oxidative stress, and cell death can result in neuropathy and cognitive impairment
Niacin (Vitamin B3)
- Important in oxidation-reduction reactions
- Active forms are NAD+ and NADP+
- Functions in key metabolic pathways such as glycolysis
- High doses of nicotinic acid, for lipid lowering, can cause vasodilation and facial flushing
- Can result in intrahepatic cholestasis, leading to jaundice
- Niacin deficiency is caused by corn-heavy diets, carcinoid tumors, and Hartnup disease
- Carcinoid tumors consume tryptophan, reducing niacin synthesis
- Deficiency leads to pellagra, whose symptoms are characterized by the "3 Ds": dementia, dermatitis, and diarrhea
- Insufficient NAD+ and NADP+ production impairs cellular metabolism and the electron transport chain
Pyridoxine (Vitamin B6)
- Key to neurotransmitter synthesis (dopamine, serotonin, GABA)
- Participates in heme synthesis and DNA production
- Deficiency results from malnutrition, alcoholism, malabsorption, dialysis, pregnancy, and certain medications
- Drugs like isoniazid and hydralazine can interfere with pyridoxine metabolism
- Deficiency causes symptoms similar to pellagra (dermatitis and deformation)
- Disrupts heme synthesis, leading to microcytic anemia and ring sideroblasts
- Impairs myelin production, causing peripheral neuropathy
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