BCSE BCSE - Basic and Clinical Sciences Examination Clinical Nutrition and Metabolism Questions and Answers 4 — Questions and Answers
Question 1: A patient with short bowel syndrome after extensive ileal resection is at greatest risk for deficiency of which nutrient?
- Vitamin B12 (Correct answer)
- Vitamin C
- Thiamine
- Folate
Correct answer: Vitamin B12
Vitamin B12 is exclusively absorbed in the terminal ileum via intrinsic factor-mediated transport, so ileal resection causes B12 deficiency.
Question 2: Which metabolic pathway is primarily responsible for synthesizing glucose from amino acids during prolonged fasting?
- Glycogenolysis
- Gluconeogenesis (Correct answer)
- Glycolysis
- Pentose phosphate pathway
Correct answer: Gluconeogenesis
Gluconeogenesis converts glucogenic amino acids (e.g., alanine, glutamine) into glucose in the liver during prolonged fasting when glycogen stores are depleted.
Question 3: Refeeding syndrome is most closely associated with a precipitous drop in serum levels of which electrolyte?
- Sodium
- Calcium
- Phosphate (Correct answer)
- Chloride
Correct answer: Phosphate
Refeeding causes a rapid shift of phosphate into cells driven by insulin release and anabolic activity, resulting in life-threatening hypophosphatemia.
Question 4: A 55-year-old woman is found to have pellagra. Which vitamin deficiency is responsible for this condition?
- Niacin (B3) (Correct answer)
- Riboflavin (B2)
- Pyridoxine (B6)
- Cobalamin (B12)
Correct answer: Niacin (B3)
Pellagra is caused by niacin (vitamin B3) deficiency and presents with the classic triad of dermatitis, diarrhea, and dementia.
Question 5: In the fasted state, the liver preferentially produces which ketone body as the primary export fuel for the brain?
- Acetone
- Acetoacetate
- Beta-hydroxybutyrate (Correct answer)
- Malonyl-CoA
Correct answer: Beta-hydroxybutyrate
Beta-hydroxybutyrate is the predominant ketone body exported by the liver during prolonged fasting and is the major alternative fuel for the brain.
Question 6: Which enzyme deficiency leads to phenylketonuria (PKU), resulting in accumulation of phenylalanine?
- Phenylalanine hydroxylase (Correct answer)
- Tyrosine hydroxylase
- Homogentisate oxidase
- Fumarylacetoacetase
Correct answer: Phenylalanine hydroxylase
PKU results from deficiency of phenylalanine hydroxylase, the enzyme that converts phenylalanine to tyrosine in the liver.
Question 7: A patient receiving total parenteral nutrition (TPN) develops essential fatty acid deficiency. Which clinical sign is most characteristic?
- Peripheral neuropathy
- Scaly dermatitis and alopecia (Correct answer)
- Night blindness
- Megaloblastic anemia
Correct answer: Scaly dermatitis and alopecia
Essential fatty acid deficiency (linoleic and alpha-linolenic acid) characteristically presents with scaly dermatitis, alopecia, and impaired wound healing.
BCSE BCSE - Basic and Clinical Sciences Examination Clinical Nutrition and Metabolism Questions and Answers 4
A patient with short bowel syndrome after extensive ileal resection is at greatest risk for deficiency of which nutrient?