Nutritional requirements and disorders US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Nutritional requirements and disorders. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Nutritional requirements and disorders US Medical PG Question 1: 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
Nutritional requirements and disorders 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.
Nutritional requirements and disorders US Medical PG Question 2: A 5-month-old boy is brought to the pediatrician by his parents, who began noticing that the infant was not able to hold his head upright when sitting or in a prone position. Upon examination, the infant has a musty odor, fair skin with patches of eczema, and blue eyes. The pediatrician orders laboratory tests and prescribes a special diet. Which of the following amino acids becomes essential and must be supplemented in this patient's condition?
- A. Thiamine
- B. Large neutral amino acids
- C. Arginine
- D. Phenylalanine-free amino acid formula
- E. Tyrosine (Correct Answer)
Nutritional requirements and disorders Explanation: ***Tyrosine***
- This patient presents with **phenylketonuria (PKU)**, characterized by the classic triad of developmental delay, musty odor (from phenylketones in urine), and hypopigmentation (fair skin, blue eyes, eczema).
- PKU is caused by **phenylalanine hydroxylase deficiency**, which prevents the conversion of phenylalanine to tyrosine.
- Because tyrosine cannot be synthesized from phenylalanine, **tyrosine becomes a conditionally essential amino acid** in PKU patients and must be supplemented in the diet.
- Treatment consists of a phenylalanine-restricted diet with **tyrosine supplementation** to ensure adequate protein synthesis and melanin production.
*Arginine*
- Arginine becomes conditionally essential in **urea cycle disorders**, where it helps drive nitrogen excretion.
- However, this patient's presentation (musty odor, hypopigmentation, eczema) is classic for PKU, not a urea cycle disorder.
- Urea cycle disorders typically present with hyperammonemia, vomiting, lethargy, and encephalopathy—not the findings described here.
*Phenylalanine-free amino acid formula*
- This is a **dietary intervention**, not an amino acid that becomes essential.
- While phenylalanine-free formulas are crucial in PKU management, the question specifically asks which amino acid becomes essential and must be supplemented.
- Phenylalanine itself is *restricted*, not supplemented.
*Thiamine*
- Thiamine (vitamin B1) is a **vitamin**, not an amino acid.
- It is a cofactor for enzymes in carbohydrate metabolism and is deficient in beriberi and Wernicke-Korsakoff syndrome.
- It is not relevant to PKU management.
*Large neutral amino acids*
- Large neutral amino acids (LNAAs) can be used as an **adjunctive therapy** in PKU to compete with phenylalanine for transport across the blood-brain barrier.
- However, they are not the amino acid that becomes conditionally essential due to the metabolic block.
- The primary nutritional requirement is **tyrosine supplementation** to replace what cannot be synthesized.
Nutritional requirements and disorders US Medical PG Question 3: A 1-year-old male presents to his pediatrician for a well-child visit. Through a history from the mother and physical examination, the pediatrician learns that the baby babbles non-specifically, takes several steps independently, and picks up his cereal using two fingers. His weight is currently 22 lbs (birth-weight 6 lbs, 9 oz), and his height is 30 inches (birth length 18 inches). Are there any aspects of this child's development that are delayed?
- A. Fine motor skill delay
- B. Language delay (Correct Answer)
- C. Inadequate growth
- D. Gross motor skill delay
- E. There are no developmental concerns
Nutritional requirements and disorders Explanation: ***Language delay***
- At 1 year of age, a child should typically be babbling with **specific sounds** and attempting to say their **first words**.
- The child's non-specific babbling suggests a delay in typical **expressive language development**.
*Fine motor skill delay*
- The child is able to pick up cereal using **two fingers**, indicating the development of a **pincer grasp**.
- This is an **age-appropriate fine motor skill** for a 1-year-old.
*Inadequate growth*
- The child has over **tripled his birth weight** (from 6 lbs, 9 oz to 22 lbs) and more than doubled his birth length (from 18 to 30 inches), which are **normal growth patterns** for the first year of life.
- While weight values can be plotted on growth charts, the provided information strongly suggests **adequate growth**.
*Gross motor skill delay*
- The child is taking **several steps independently**, which is an **age-appropriate gross motor milestone** for a 1-year-old.
- Many children take their first independent steps between 9 and 15 months.
*There are no developmental concerns*
- While many milestones are met, the **non-specific babbling** at 1 year strongly suggests a **language delay**.
- It is crucial to identify and address any potential delays early for intervention.
Nutritional requirements and disorders US Medical PG Question 4: A 12-month-old boy presents with pallor, fatigue, and conjunctival pallor. Examination reveals a grade II systolic ejection murmur. Labs show: Leukocytes 6,500/mm^3, Hemoglobin 6.4 g/dL, Platelets 300,000/mm^3, MCV 71 µm^3, Reticulocytes 2.0%, Serum iron 34 mcg/dL, Ferritin 6 ng/mL (normal 7-140 ng/mL), TIBC 565 mcg/dL (normal 240-450 mcg/dL). Peripheral smear shows microcytosis and hypochromia. In addition to starting iron supplementation, what dietary modification is most important to address the underlying cause?
- A. Administer deferoxamine
- B. Limit milk intake (Correct Answer)
- C. Echocardiogram
- D. Measure lead level
- E. Iron supplementation
Nutritional requirements and disorders Explanation: ***Limit milk intake***
- The patient's presentation and lab results (low Hb, low MCV, low ferritin, high TIBC) are highly indicative of **iron deficiency anemia**. Excessive cow's milk intake (typically >24 oz/day) in infants is a leading cause of iron deficiency through multiple mechanisms: displacing iron-rich foods from the diet, causing occult gastrointestinal blood loss, and impairing iron absorption due to calcium content.
- With severe anemia (Hb 6.4 g/dL), **iron supplementation is essential** and should be started immediately (3-6 mg/kg/day elemental iron). However, addressing the underlying **dietary cause** by limiting milk to 16-24 oz/day and encouraging iron-rich foods (meat, fortified cereals) is crucial to prevent recurrence and ensure long-term resolution.
- This question tests understanding of the **etiology** of nutritional iron deficiency in toddlers, where excessive milk consumption is the most common preventable cause.
*Administer deferoxamine*
- **Deferoxamine** is a chelating agent used to treat **iron overload** (hemochromatosis, transfusional iron overload, acute iron poisoning).
- This patient has severe iron **deficiency**, so removing iron would be harmful and contraindicated.
*Echocardiogram*
- An **echocardiogram** evaluates cardiac structure and function, indicated for suspected structural heart disease or pathologic murmurs.
- The grade II systolic ejection murmur is likely a **flow murmur** from high cardiac output due to severe anemia. Once anemia is corrected, the murmur should resolve. Echocardiogram is not the priority and would only be considered if the murmur persists after anemia correction.
*Measure lead level*
- **Lead poisoning** can cause microcytic anemia and should be considered in at-risk children.
- However, lead poisoning typically shows **normal or elevated ferritin** (lead causes anemia of chronic disease plus iron dysregulation), whereas this patient has **very low ferritin (6 ng/mL)** and **markedly elevated TIBC (565)**, which are classic for iron deficiency, not lead toxicity.
*Iron supplementation*
- **Iron supplementation is absolutely necessary** for this patient with severe anemia (Hb 6.4 g/dL) and should be started immediately along with dietary counseling.
- However, the question specifically asks for the dietary modification needed **in addition to** iron supplementation to address the **underlying cause**. Without limiting excessive milk intake, iron deficiency will likely recur even with supplementation.
Nutritional requirements and disorders US Medical PG Question 5: A 55-year-old woman presents with fatigue. She says her symptoms are present throughout the day and gradually started 4 months ago. Her past medical history is significant for rheumatoid arthritis–treated with methotrexate, and diabetes mellitus type 2–treated with metformin. The patient is afebrile, and her vital signs are within normal limits. A physical examination reveals pallor of the mucous membranes. Initial laboratory tests show hemoglobin of 7.9 g/dL, hematocrit of 22%, and mean corpuscular volume of 79 fL. Which of the following is the best next diagnostic step in this patient?
- A. Serum ferritin level and total iron-binding capacity (TIBC)
- B. Serum ferritin and serum iron levels
- C. Serum ferritin and soluble transferrin receptor levels (Correct Answer)
- D. Serum iron level
- E. Serum ferritin level
Nutritional requirements and disorders Explanation: ***Serum ferritin and soluble transferrin receptor levels***
- This patient has **anemia** (hemoglobin 7.9 g/dL) with **microcytic** (MCV 79 fL) and **hypochromic** features, suggesting either **iron deficiency anemia (IDA)** or **anemia of chronic disease (ACD)**. Given her history of **rheumatoid arthritis**, ACD is highly likely, but co-existing IDA needs to be excluded.
- **Serum ferritin** is an acute-phase reactant, so it can be elevated in ACD masking a co-existing iron deficiency. **Soluble transferrin receptor (sTfR)** levels are increased in IDA and remain normal or only mildly elevated in ACD, making it a reliable marker to differentiate between these two conditions when ferritin is uninterpretable due to inflammation.
*Serum ferritin level and total iron-binding capacity (TIBC)*
- While these tests are useful for diagnosing iron deficiency, **ferritin** can be falsely elevated in the context of inflammation (e.g., from **rheumatoid arthritis**), making it unreliable for diagnosing IDA in this patient.
- **TIBC** can be decreased in ACD, complicating its interpretation for IDA when inflammation is present.
*Serum ferritin and serum iron levels*
- As mentioned, **serum ferritin** is an acute-phase reactant and may be elevated due to **rheumatoid arthritis**, potentially masking **iron deficiency**.
- **Serum iron levels** fluctuate significantly and are not a reliable standalone indicator for iron status, especially in the context of chronic disease.
*Serum iron level*
- **Serum iron levels** are highly variable and not sufficient for diagnosing **iron deficiency** or differentiating it from **anemia of chronic disease**.
- A low serum iron can be seen in both IDA and ACD but does not provide definitive diagnostic information on its own.
*Serum ferritin level*
- Measuring **serum ferritin** alone is insufficient because it is an **acute-phase reactant** that can be elevated due to the patient's **rheumatoid arthritis**, even if she has co-existing **iron deficiency anemia**.
- A normal or high ferritin level in this context does not rule out **iron deficiency**.
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