Refeeding Risk in a Malnourished Patient with Suspected Eating Disorder
A 22-year-old woman with anorexia nervosa (restricting type) is admitted to a medical unit after fainting at work. On admission: BMI 13.8 kg/m², weight 37.2 kg, height 1.64 m. She reports eating 'very little' for 6 months and drinking 3–4 L of water daily. Labs: potassium 2.9 mmol/L, magnesium 0.62 mmol/L, phosphate 0.78 mmol/L, albumin 38 g/L, glucose 3.4 mmol/L. She is bradycardic (48 bpm) and reports palpitations. The medical team asks you to start enteral nutrition because she 'refuses to eat' and they want rapid weight restoration. She is alert, oriented, and states she does not want a feeding tube.
1. Assess this patient's refeeding risk and justify your nutrition plan in the first 72 hours, including caloric targets and monitoring.
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Risk assessment: This patient has multiple high-risk features for refeeding syndrome: BMI <16, minimal intake >5 days, low baseline phosphate, potassium and magnesium, and likely total body depletion of thiamine and electrolytes despite normal serum albumin (albumin is a poor acute marker). The bradycardia and palpitations warrant cardiac monitoring.
Plan:
- Do not start at high calories. Begin at 10–15 kcal/kg/day (~370–560 kcal/day), advancing slowly over 4–7 days (e.g., +200 kcal every 48 h) only if electrolytes remain stable.
- Start thiamine 200–300 mg before feeding and daily for at least 10 days; add a balanced multivitamin.
- Check phosphate, potassium, magnesium at baseline and then 4–6 hourly initially; replace aggressively per protocol (oral or IV depending on severity).
- Monitor fluid balance and restrict excess free water; she is drinking 3–4 L/day, which risks dilutional hyponatremia.
- Daily ECG/cardiac monitoring given bradycardia.
- Ethical/consent point: She has decision-making capacity and declines a tube. A nasogastric tube cannot be placed against her refusal. Respect autonomy, involve the eating disorder team, and offer oral/nutritional supplements; if capacity is later questioned, follow your jurisdiction's capacity and involuntary treatment framework.
2. The team asks why you are not 'just feeding her up.' Explain the physiological rationale for slow advancement and the specific electrolyte shifts involved.
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During starvation, the body shifts to fat oxidation and ketone use, and intracellular stores of phosphate, potassium and magnesium become depleted even when serum levels look near-normal. Insulin secretion is suppressed.
When carbohydrate is reintroduced, insulin rises and drives glucose and phosphate into cells. Glycolysis consumes phosphate (phosphorylated intermediates), and anabolism increases demand for phosphate, potassium and magnesium. Serum phosphate can fall precipitously within 24–72 hours, causing hypophosphatemia, which impairs ATP synthesis and can cause cardiac failure, arrhythmias, rhabdomyolysis, respiratory failure and seizures. Hypokalemia and hypomagnesemia compound cardiac risk; thiamine deficiency (exacerbated by carbohydrate load) can precipitate Wernicke's encephalopathy or wet beriberi.
Slow, staged advancement limits the insulin surge and allows electrolyte replacement to keep pace. This is why the team's instinct to 'feed her up' is physiologically dangerous in severe malnutrition.
3. On day 3 she develops confusion, nystagmus and ataxia. What is your differential and immediate action?
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Differential: Wernicke's encephalopathy (thiamine deficiency) is the leading concern given malnutrition plus carbohydrate reintroduction. Other considerations: severe hyponatremia from excessive water intake, hypoglycemia, hypophosphatemia, or hypomagnesemia.
Immediate action:
- Treat empirically for Wernicke's: IV thiamine (e.g., 500 mg IV three times daily for 2–3 days, then reassess) before or alongside any glucose-containing fluids.
- Check capillary glucose, serum sodium, phosphate, magnesium and potassium urgently.
- Review all fluids given; restrict hypotonic fluids if sodium is low.
- Escalate to the medical team and document. Do not delay thiamine while waiting for labs.
Teaching point: In any malnourished patient receiving carbohydrate, thiamine must be given first or concurrently. Confusion, ophthalmoplegia/nystagmus and ataxia are the classic triad but the full triad is present in only a minority.