Synopsis
Identify undernutrition at any body size, choose safe and consented nutrition support, and prevent or treat refeeding electrolyte, thiamine, fluid and cardiac complications.
- Malnutrition can occur at any BMI, including obesity, oedema, pregnancy and after bariatric surgery; weight alone is not a nutritional assessment.
- NICE considers nutrition support when BMI is below 18.5, unintentional loss exceeds 10% in three to six months, or BMI below 20 accompanies more than 5% loss.
- Little or no intake for more than five days also creates nutrition-support need and refeeding considerations even when formal BMI criteria are not met.
Key red flags
A falling phosphate, potassium or magnesium after nutrition starts with oedema, weakness, arrhythmia, respiratory difficulty or neurological change indicates clinically important refeeding physiology.
Investigation priorities
Identify risk from BMI, weight loss and acute intake reduction consistently.
Management branches
Hospital admission, first relevant outpatient contact or clinical concern about intake or weight loss.
- Use MUST or the local validated tool, obtaining recent weight trajectory and intake duration and adapting measurements for oedema, disability or inability to stand.
- Assess disease cause, swallowing, GI function, muscle and function, alcohol, medicines, mental health, food access, capacity and the person's treatment goals.
Key medicines
Thiamine and vitamin B for high refeeding riskGive oral thiamine 200 to 300 mg daily plus vitamin B co-strong 1 or 2 tablets three times daily immediately before and during the first 10 days of feeding; use intravenous thiamine when oral absorption is unreliable or neurological deficiency is suspected.
Balanced multivitamin and trace-element supplementGive a complete once-daily oral or intravenous multivitamin and trace-element preparation from before feeding and for at least the first 10 days, then continue according to nutritional cause and route.