Vitamins & Minerals

Topics in this chapter

• Vitamin Classification and Functions
• Fat-Soluble Vitamin Physiology
• Water-Soluble Vitamin Metabolism
• Vitamin Deficiency and Clinical Disorders
• Major Mineral Physiology
• Trace Mineral Disorders

Practice questions

1. Question 1Q-9B6CEA

   A 45-year-old chronic alcoholic is brought to the emergency department with acute confusion, ataxia, and ophthalmoplegia. Which of the following enzymes is most likely inhibited or impaired in this patient due to a vitamin cofactor deficiency?

   1. A.Glucose-6-phosphate dehydrogenase
   2. B.Transketolase
   3. C.Methylmalonyl-CoA mutase
   4. D.Homocysteine methyltransferase
   See the answer and solution
2. Question 2Q-97A315

   A 3-year-old child presents with night blindness and Bitot spots on the conjunctiva. Dietary history reveals a predominantly cereal-based diet lacking green leafy vegetables and animal products. Which of the following intracellular processes is primarily dependent on the active metabolite of the deficient vitamin?

   1. A.Gamma-carboxylation of clotting factors
   2. B.Glycoprotein synthesis and cellular differentiation
   3. C.Collagen hydroxylation
   4. D.Calcium and phosphate reabsorption in the renal tubules
   See the answer and solution
3. Question 3Q-9CDB9F

   An exclusive breastfed 6-month-old infant presents with craniotabs, delayed closure of the anterior fontanelle, and widening of the wrists. Laboratory findings reveal hypocalcemia, hypophosphatemia, and elevated alkaline phosphatase. Which of the following is the primary mechanism of action of the active form of the vitamin deficient in this patient?

   1. A.Inhibition of osteoclast activity via calcitonin release
   2. B.Genomic action binding to intracellular receptors to increase intestinal calcium-binding protein
   3. C.Direct enzymatic phosphorylation of bone matrix proteins
   4. D.Enhancement of renal calcium excretion to prevent nephrocalcinosis
   See the answer and solution
4. Question 4Q-E66483

   A patient presents with megaloblastic anemia, but serum levels of folate and vitamin B12 are within normal limits. Further investigation reveals a rare inborn error of metabolism affecting pyrimidine synthesis, specifically presenting with massive urinary excretion of orotic acid. This condition responds to administration of high doses of which of the following vitamins?

   1. A.Zinc
   2. B.Copper
   3. C.Iron
   4. D.Manganese
   See the answer and solution
5. Question 5Q-DE020A

   A 50-year-old man with chronic renal failure presents with bone pain and proximal muscle weakness. Laboratory studies show hyperphosphatemia and hypocalcemia. Bone biopsy reveals osteomalacia and osteitis fibrosa cystica. Resistance to which of the following vitamins or its active metabolites is a hallmark contributor to renal osteodystrophy?

   1. A.Vitamin A
   2. B.Vitamin D
   3. C.Vitamin E
   4. D.Vitamin K
   See the answer and solution