A 28-year-old woman with severe anorexia is admitted for nutritional rehabilitation. Within 48 hours of initiating enteral feeding, she develops muscle weakness, cardiac arrhythmias, and respiratory distress. Which metabolic abnormality is most characteristically responsible?

1. A

   A. Hyponatremia

2. B

   B. Hypocalcemia

3. C

   C. Hypophosphatemia

4. D

   D. Hyperkalemia

Appeared in: INI-CET EXAM -2026

Explanation

• The patient's clinical picture of a severely malnourished individual (anorexia) developing acute cardiopulmonary and muscular collapse after starting nutritional support is the classic presentation of refeeding syndrome.
• The core pathophysiological event in refeeding syndrome is a surge in insulin following carbohydrate reintroduction.
• This insulin surge drives phosphate, potassium, and magnesium from the bloodstream into the cells to fuel metabolic processes.
• The resulting severe hypophosphatemia is the hallmark of the syndrome and is directly responsible for the symptoms, as phosphate is essential for ATP (energy) production.
• Impaired ATP production leads to muscle weakness (including the diaphragm, causing respiratory distress) and cardiac dysfunction (arrhythmias, heart failure).

Why Other Options Were Wrong

• Option A: While fluid and sodium retention can occur in refeeding syndrome, leading to fluid overload, severe hyponatremia is not the characteristic metabolic abnormality that causes the acute cardiopulmonary failure seen in this scenario.
• Option B: Hypocalcemia can cause arrhythmias and muscle issues (tetany), but it is not the primary metabolic derangement of refeeding syndrome. It can occur secondarily to hypomagnesemia, which is another feature of the syndrome, but hypophosphatemia is the key driver of the most severe complications.
• Option D: This is the opposite of what occurs in refeeding syndrome. The insulin surge drives potassium into the cells, leading to profound hypokalemia, not hyperkalemia.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Refeeding Syndrome and its hallmark metabolic derangement as background academic context rather than a clinical decision trigger.
• Nurses must identify patients at high risk for refeeding syndrome, including those with anorexia nervosa, chronic alcoholism, cancer cachexia, or prolonged periods of poor nutritional intake.
• The cornerstone of prevention is to 'start low and go slow.' Nutritional support should be initiated at a low caloric level (e.g., 10-20 kcal/kg/day) and advanced cautiously over several days.
• Meticulous nursing monitoring is critical. This includes daily monitoring of electrolytes (especially phosphate, potassium, and magnesium) before and for at least the first 5-7 days of refeeding, as well as monitoring vital signs, fluid balance, and cardiac rhythm.

How to Approach the Question

• First, analyze the patient profile: a 28-year-old with severe anorexia. This immediately flags the patient as severely malnourished and at high risk for complications of nutritional therapy.
• Next, identify the sequence of events: the patient was stable, then enteral feeding was initiated, and within 48 hours, she developed acute, life-threatening symptoms (muscle weakness, arrhythmias, respiratory distress).
• Connect the profile and the timeline. A malnourished patient rapidly deteriorating after the start of feeding is the classic vignette for Refeeding Syndrome.
• Recall the hallmark metabolic abnormality of refeeding syndrome. The key event is an insulin-driven intracellular shift of electrolytes. The most critical and characteristic of these is phosphate.
• Evaluate the options based on this knowledge. Hypophosphatemia directly explains the symptoms due to its role in ATP production. Hypokalemia and hypomagnesemia also occur but hypophosphatemia is the most characteristic cause of this specific constellation of severe symptoms. Hyperkalemia is the opposite of what is expected.

Concept Tested & Keywords

• Concept Tested: Refeeding Syndrome and its hallmark metabolic derangement.
• Stem keywords: anorexia, nutritional rehabilitation, enteral feeding, muscle weakness, cardiac arrhythmias, respiratory distress
• Lead-in keywords: most characteristically responsible
• Clinical cues: Patient with severe anorexia, a high-risk condition for malnutrition.
• Clinical cues: Symptoms develop within 48 hours of initiating feeding, a classic timeframe for refeeding syndrome.

Question ID

QbF3fFaDcIEGAaUPMGU0V-

Copy ID

Reference Book

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 552-554, 476-478, 477-479