Refeeding Syndrome — MRCPsych Paper B MCQ

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ModerateEating DisordersRefeeding SyndromeMRCPsych Paper B

A 19-year-old woman with anorexia nervosa is admitted after negligible nutritional intake for 12 days. Her serum phosphate is initially normal. On the third day after oral refeeding is started, she develops peripheral oedema, confusion and a cardiac arrhythmia. Her serum phosphate has fallen to 0.30 mmol/L. What is the most likely unifying diagnosis?

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Correct answer: C — Refeeding syndrome

The answer is **refeeding syndrome**. Following prolonged starvation, reintroduction of nutrition stimulates insulin release and drives phosphate, potassium and magnesium into cells. The characteristic timing—within 3 days of starting refeeding—together with a marked new fall in phosphate, oedema, confusion and arrhythmia indicates established refeeding syndrome rather than isolated refeeding hypophosphataemia. Cardiac failure may cause oedema and can occur as a complication, but it does not explain the acute phosphate fall after feeding. Wernicke encephalopathy can cause confusion during refeeding but does not account for hypophosphataemia, oedema and arrhythmia. Starvation ketoacidosis typically develops before nutritional restoration, while SIADH primarily causes dilutional hyponatraemia rather than hypophosphataemia.

Reference: Royal College of Psychiatrists. Medical Emergencies in Eating Disorders: Guidance on Recognition and Management (MEED), CR233, section 4b and Table 7, 2022. https://www.rcpsych.ac.uk/docs/default-source/improving-care/better-mh-policy/college-reports/college-report-cr233-medical-emergencies-in-eating-disorders-%28meed%29-guidance.pdf?sfvrsn=2d327483_55