Vitamin/mineral functions and deficiencies US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Vitamin/mineral functions and deficiencies. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Vitamin/mineral functions and deficiencies US Medical PG Question 1: You are counseling a pregnant woman who plans to breast-feed exclusively regarding her newborn's nutritional requirements. The child was born at home and the mother only plans for her newborn to receive vaccinations but no other routine medical care. Which vitamins should be given to the newborn?
- A. Vitamin B6
- B. Vitamin K and Vitamin D (Correct Answer)
- C. Vitamin K
- D. Folic acid
- E. Vitamin D
Vitamin/mineral functions and deficiencies Explanation: ***Vitamin K and Vitamin D***
- All newborns should receive a prophylactic dose of **Vitamin K** to prevent **Vitamin K Deficiency Bleeding (VKDB)**, as placental transfer is poor and breast milk contains low levels.
- Breastfed infants, especially those exclusively breastfed, require **Vitamin D** supplementation (400 IU daily) to prevent **rickets**, as breast milk Vitamin D levels are often insufficient.
*Vitamin B6*
- While essential for development, **Vitamin B6** supplementation is not routinely recommended for all healthy newborns, especially those exclusively breastfed by a healthy mother.
- Deficiency in newborns is rare and typically associated with specific metabolic disorders or maternal malnutrition, which are not suggested here.
*Vitamin K*
- While **Vitamin K** is critically important for all newborns, it is only one of the essential vitamins needed for breastfed infants.
- Exclusive breastfeeding also necessitates **Vitamin D** supplementation, making this option incomplete.
*Folic acid*
- **Folic acid** (Vitamin B9) is crucial during pregnancy for preventing neural tube defects and is found in adequate amounts in breast milk for a healthy full-term infant.
- Routine supplementation of folic acid is not recommended for healthy newborns, as deficiency is rare.
*Vitamin D*
- While **Vitamin D** supplementation is essential for exclusively breastfed infants, this option is incomplete as it misses the critical need for **Vitamin K** prophylaxis at birth.
- Both vitamins are critical for newborn health in this scenario.
Vitamin/mineral functions and deficiencies US Medical PG Question 2: A 29-year-old woman came to the emergency department due to severe symptoms of intoxication and unexplained convulsions. She is accompanied by her husband who reports that she takes disulfiram. There is no prior personal and family history of epilepsy. She shows signs of confusion, hyperirritability, and disorientation. On further evaluation, the patient is noted to have stomatitis, glossitis, and cheilosis. A chest X-ray is unremarkable. The deficiency of which of the vitamins below is likely to be the major cause of this patient’s symptoms?
- A. B12
- B. B6 (Correct Answer)
- C. B9
- D. B2
- E. B3
Vitamin/mineral functions and deficiencies Explanation: ***B6***
- The patient's presentation of **seizures, confusion, and oral symptoms (stomatitis, glossitis, cheilosis)** in the context of **disulfiram use** strongly suggests **pyridoxine (vitamin B6) deficiency**.
- **Disulfiram inhibits pyridoxine phosphokinase**, which converts pyridoxine to its active form (pyridoxal-5-phosphate), leading to functional B6 deficiency.
- **Seizures are a hallmark of B6 deficiency** because pyridoxal-5-phosphate is a cofactor for glutamic acid decarboxylase, which synthesizes GABA; reduced GABA leads to increased neuronal excitability and seizures.
- B6 deficiency also causes **peripheral neuropathy, cheilosis, glossitis, and stomatitis**.
*B2*
- Vitamin B2 (riboflavin) deficiency does cause **stomatitis, glossitis, and cheilosis**, along with seborrheic dermatitis and normocytic anemia.
- However, **riboflavin deficiency does not typically cause seizures**, which is the most acute and concerning symptom in this case.
- While disulfiram can affect multiple vitamin pathways, the seizure presentation points specifically to B6.
*B12*
- Vitamin B12 deficiency typically presents with **megaloblastic anemia** and **neurological symptoms** such as subacute combined degeneration (posterior column and corticospinal tract), peripheral neuropathy, and cognitive changes.
- The acute seizures and oral mucosal symptoms are not characteristic of B12 deficiency.
*B9*
- Vitamin B9 (folate) deficiency primarily causes **megaloblastic anemia** with symptoms of fatigue and weakness.
- While **glossitis** can occur, it's usually accompanied by anemia, and seizures are not a feature of folate deficiency.
- The clinical picture does not fit folate deficiency.
*B3*
- Vitamin B3 (niacin) deficiency causes **pellagra**, characterized by the classic triad: **dermatitis, diarrhea, and dementia** (the "3 Ds").
- While glossitis can be present, the **absence of photosensitive dermatitis and diarrhea** makes pellagra unlikely.
- Seizures are not a typical feature of pellagra.
Vitamin/mineral functions and deficiencies US Medical PG Question 3: A 61-year-old woman presents for a routine health visit. She complains of generalized fatigue and lethargy on most days of the week for the past 4 months. She has no significant past medical history and is not taking any medications. She denies any history of smoking or recreational drug use but states that she drinks "socially" approx. 6 nights a week. She says she also enjoys a "nightcap," which is 1–2 glasses of wine before bed every night. The patient is afebrile, and her vital signs are within normal limits. On physical examination, there is significant pallor of the mucous membranes. Laboratory findings are significant for a mean corpuscular volume (MCV) of 72 fL, leukocyte count of 4,800/mL, hemoglobin of 11.0 g/dL, and platelet count of 611,000/mL. Stool guaiac test is negative. She is started on oral ferrous sulfate supplements. On follow-up, her laboratory parameters show no interval change in her MCV or platelet level, and she reports good compliance with the medication. Which of the following is the best next step in the management of this patient?
- A. Transfuse the patient with whole blood
- B. Administer folate
- C. Administer iron intravenously (Correct Answer)
- D. Continue oral ferrous sulfate and supplement with omeprazole
- E. Continue oral ferrous sulfate and supplement with ascorbic acid
Vitamin/mineral functions and deficiencies Explanation: **Administer iron intravenously**
- The patient shows **microcytic anemia** (MCV 72 fL) and **thrombocytosis** (platelet count 611,000/mL), which are classic signs of **iron deficiency anemia**.
- Given the failure of oral ferrous sulfate to improve her parameters, despite likely good adherence given the repeat visit, **intravenous iron** is the next appropriate step to ensure adequate iron repletion.
*Transfuse the patient with whole blood*
- **Blood transfusion** is reserved for patients with severe, symptomatic anemia, often with a hemoglobin level much lower than 11.0 g/dL, or in cases of acute hemorrhage.
- This patient's anemia is chronic and her hemoglobin level, while low, is not critically low enough to warrant immediate transfusion.
*Administer folate*
- **Folate deficiency** typically causes **macrocytic anemia** (high MCV), not microcytic anemia, making it an inappropriate treatment for this patient.
- Though chronic alcohol use can affect folate levels, the patient's presentation is more consistent with iron deficiency.
*Continue oral ferrous sulfate and supplement with omeprazole*
- **Omeprazole** is a **proton pump inhibitor** that can actually *reduce* iron absorption by decreasing gastric acidity, making it counterproductive in treating iron deficiency.
- Continuing oral iron alone was already proven ineffective, necessitating a more aggressive approach.
*Continue oral ferrous sulfate and supplement with ascorbic acid*
- **Ascorbic acid (vitamin C)** can enhance the absorption of non-heme iron; however, since the initial trial of oral ferrous sulfate alone was ineffective, merely adding ascorbic acid may not be sufficient.
- The lack of improvement suggests either poor absorption or significant ongoing loss, which intravenous iron addresses more directly.
Vitamin/mineral functions and deficiencies US Medical PG Question 4: A 27-year-old female presents to general medical clinic for a routine checkup. She has a genetic disease marked by a mutation in a chloride transporter. She has a history of chronic bronchitis. She has a brother with a similar history of infections as well as infertility. Which of the following is most likely true regarding a potential vitamin deficiency complication secondary to this patient's chronic illness?
- A. It may result in connective tissue defects
- B. It may result in corneal vascularization
- C. It may result in the triad of confusion, ophthalmoplegia, and ataxia
- D. It may manifest itself as a prolonged PT (Correct Answer)
- E. It may be exacerbated by excessive ingestion of raw eggs
Vitamin/mineral functions and deficiencies Explanation: ***It may manifest itself as a prolonged PT***
- The patient's presentation with a **chloride transporter mutation**, chronic bronchitis, and a brother with similar infections and infertility is highly suggestive of **cystic fibrosis (CF)**.
- CF leads to **pancreatic insufficiency** and **malabsorption of fat-soluble vitamins (A, D, E, K)**. A deficiency in **vitamin K** can result in impaired synthesis of **clotting factors**, leading to a **prolonged prothrombin time (PT)**.
*It may result in connective tissue defects*
- This symptom is characteristic of **vitamin C deficiency (scurvy)**, which manifests as impaired **collagen synthesis** and fragile connective tissues.
- While CF patients can have various deficiencies, connective tissue defects are not a primary consequence of the fat-soluble vitamin deficiencies associated with CF.
*It may result in corneal vascularization*
- **Corneal vascularization** is typically associated with **riboflavin (vitamin B2) deficiency** or chronic ocular inflammation.
- This is not a common complication of the fat-soluble vitamin malabsorption seen in cystic fibrosis.
*It may result in the triad of confusion, ophthalmoplegia, and ataxia*
- This triad describes **Wernicke-Korsakoff syndrome**, which is caused by a **thiamine (vitamin B1) deficiency**.
- This deficiency is common in alcoholism or severe malnutrition but is not a direct complication of the fat-soluble vitamin malabsorption in cystic fibrosis.
*It may be exacerbated by excessive ingestion of raw eggs*
- Excessive ingestion of raw eggs can lead to **biotin (vitamin B7) deficiency** due to **avidin** binding to biotin, preventing its absorption.
- While CF patients can have various nutritional issues, this specific interaction is unrelated to the fat-soluble vitamin deficiencies caused by their pancreatic insufficiency.
Vitamin/mineral functions and deficiencies US Medical PG Question 5: A 25-year-old woman presents her physician with a complaint of feeling tired and low on energy for the past 6 months. She also has noticed she has been having trouble performing daily tasks and at times experiencing near-fainting spells. She has no recollection of similar instances in the past. Her past medical history is insignificant, except for the fact that she has been a strict vegan for the last 5 years. Her vital signs are stable. On physical examination, she is visibly pale and has decreased position and vibratory sensation in her both lower extremities. There is decreased lower limb reflexes with sensation intact. A complete blood count - done last week, - shows hemoglobin of 9.7 g/dL with an MCV of 110 fL. The serum levels of which of the following will most likely aid in the physician’s treatment plan?
- A. Methylmalonic acid (Correct Answer)
- B. Folate
- C. Homocysteine
- D. Succinyl CoA
- E. Ferritin
Vitamin/mineral functions and deficiencies Explanation: ***Methylmalonic acid***
- Elevated **methylmalonic acid (MMA)** levels, along with **macrocytic anemia (MCV 110 fL)** and neurological symptoms (decreased position and vibratory sensation, lower limb reflexes), are highly suggestive of **vitamin B12 deficiency**.
- As a strict **vegan**, the patient is at high risk for vitamin B12 deficiency because B12 is primarily found in animal products.
*Folate*
- While folate deficiency can cause **macrocytic anemia**, it typically does **not cause neurological symptoms** like those described.
- Furthermore, the neurological symptoms point more strongly towards vitamin B12 deficiency, which is crucial to differentiate from folate deficiency as folate supplementation alone can mask B12 deficiency and worsen neurological symptoms.
*Homocysteine*
- Elevated **homocysteine** can be seen in both **vitamin B12 and folate deficiencies**, making it less specific for differentiating between the two.
- Therefore, while it might be elevated, measuring MMA is more specific for confirming vitamin B12 deficiency.
*Succinyl CoA*
- **Succinyl CoA** is an intermediate in metabolism and is not directly measured to diagnose vitamin deficiencies.
- While its metabolism is affected by vitamin B12, measuring its precursor, **methylmalonic acid**, is the clinical diagnostic test.
*Ferritin*
- **Ferritin** levels are used to assess **iron stores** and diagnose iron deficiency anemia, which typically presents as **microcytic anemia**, not the **macrocytic anemia** seen in this patient (MCV 110 fL).
- Iron deficiency would not explain the neurological symptoms.
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