Refeeding syndrome
Board exam relevance: in 3 of 105 exam reports · rank 111- Synonyms
- refeeding, refeeding hypophosphataemia, nutritional recovery syndrome
- Specialty
- Internal medicine · Electrolytes & acid–base
- Last updated
- 10/2026 · Dr. Pascal Bafteh
Contents
Definition
Refeeding syndrome refers to the metabolic and clinical disturbances that can occur in undernourished or starved people when nutrition is restarted – orally, via a feeding tube or parenterally. They include electrolyte shifts (above all hypophosphatemia, hypokalemia and hypomagnesemia), fluid retention with fluid overload, hyperglycemia, cardiac arrhythmias and diarrhea.
Occurrence & epidemiology
People at particular risk are those with protein-energy undernutrition, for example in anorexia nervosa, chronic alcohol use disorder, cancer-related cachexia, severe swallowing disorders or in older people with multiple illnesses. Clinically significant acute hypophosphatemia typically occurs on refeeding after prolonged undernutrition, during parenteral nutrition and in acute alcohol use disorder.
Aetiopathogenesis
In starvation, total body stores of phosphate, potassium, magnesium and thiamine are often depleted, while serum levels may still be normal. When carbohydrate intake resumes, insulin secretion rises; glucose, phosphate and potassium are taken up into cells, for example for glycogen synthesis. Serum levels can therefore fall abruptly. Because thiamine is needed for glucose metabolism, glucose intake can unmask or worsen pre-existing thiamine deficiency. At the same time sodium and water are retained.
Risk factors
According to the criteria of the British NICE guideline, a high risk exists with at least one of the following features:
- body mass index below 16 kg/m²
- unintentional weight loss of more than 15% within the last 3 to 6 months
- little or no nutritional intake for more than 10 days
- low potassium, phosphate or magnesium levels before feeding
A high risk also exists with at least two of the following features:
- body mass index below 18.5 kg/m²
- unintentional weight loss of more than 10% within the last 3 to 6 months
- little or no nutritional intake for more than 5 days
- a history of alcohol misuse or certain drugs
Clinical features
- Fluid balance and heart: edema, fluid overload up to heart failure and cardiac arrhythmias.
- Hypophosphatemia: muscle weakness, respiratory failure, heart failure, rhabdomyolysis, hemolytic anemia, impaired leukocyte and platelet function and encephalopathy with seizures progressing to coma.
- Hypokalemia and hypomagnesemia: muscle weakness, tetany and cardiac arrhythmias.
- Thiamine deficiency: Wernicke encephalopathy with apathy, nystagmus, ataxia, ophthalmoplegia and impaired consciousness.
- Metabolism and gut: hyperglycemia and diarrhea.
Diagnosis
- Risk identification: body mass index, unintentional weight loss over recent months, duration of absent or low nutritional intake, alcohol history and comorbidities.
- Laboratory tests: phosphate, potassium, magnesium, sodium, glucose and renal function before and after nutrition is restarted. Hypophosphatemia is present below 0.81 mmol/L; mild 0.65 to 0.81, moderate 0.32 to 0.65 and severe below 0.32 mmol/L.
- Clinical signs: weight course, edema, respiratory rate, pulse and neurological abnormalities.
- ECG: in electrolyte disturbances and arrhythmias.
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Note: Learning content for medical education – not a treatment recommendation and no substitute for diagnosis or treatment decisions in individual cases. Treatment and management are deliberately not covered on this page.