Refeeding syndrome in critical illness — FFICM MCQ

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ModerateRenal and MetabolicRefeeding syndrome in critical illnessFFICM

A 48-year-old man with alcohol dependence is started on enteral feeding after 10 days of minimal intake. Within 36 hours he develops weakness, tachycardia and difficulty weaning from ventilation. Phosphate is 0.32 mmol/L, potassium is 2.8 mmol/L and magnesium is 0.48 mmol/L. What is the most likely diagnosis?

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Correct answer: D — Refeeding syndrome

The correct answer is D, refeeding syndrome. This patient has had little or no nutritional intake for more than 10 days (a NICE CG32 high risk criterion) and developed profound hypophosphataemia, hypokalaemia and hypomagnesaemia within 36 hours of reintroducing feed, with weakness, tachycardia and ventilator weaning failure reflecting neuromuscular and cardiac dysfunction from the electrolyte shift. The mechanism is an abrupt switch from catabolism to carbohydrate driven insulin release, which drives intracellular uptake of phosphate, potassium and magnesium along with glucose, depleting already low total body stores. Alcohol dependence with prolonged poor intake is a classic high risk group for this presentation. The combination of timing (within days of feeding), the specific triad of low phosphate, potassium and magnesium, and the clinical context is diagnostic. Why the other options are wrong: B. Tumour lysis syndrome: causes hyperphosphataemia, hyperkalaemia and hyperuricaemia from cell lysis, not the hypophosphataemia and hypokalaemia seen here, and requires a lysing tumour burden which is absent. C. Acute adrenal insufficiency: typically causes hyponatraemia and hyperkalaemia with hypotension, not the hypokalaemia and hypophosphataemia pattern described. A. Propofol infusion syndrome: presents with metabolic acidosis, rhabdomyolysis, hyperkalaemia and cardiac failure related to high dose prolonged propofol infusion, which is not mentioned in this stem. E. Uraemic encephalopathy: relates to renal failure with rising urea and altered consciousness, not to electrolyte depletion following reintroduction of feed, and no renal impairment is given. Key point: Profound hypophosphataemia, hypokalaemia and hypomagnesaemia appearing within 1 to 3 days of restarting feeding in a previously starved, high risk patient (such as one with alcohol dependence and over 10 days of minimal intake) is refeeding syndrome until proven otherwise.

Reference: NICE CG32, Nutrition support for adults: oral nutrition support, enteral tube feeding and parenteral nutrition, Box 1 criteria for determining people at high risk of developing refeeding problems, https://www.nice.org.uk/guidance/cg32