Refeeding Syndrome
Summary
Refeeding syndrome is a potentially fatal metabolic complication that occurs when nutrition is reintroduced to a severely malnourished patient. During starvation, the body switches from carbohydrate to fat metabolism and depletes intracellular stores of phosphate, potassium, and magnesium. When feeding resumes (especially with carbohydrates), insulin is released, driving electrolytes into cells and causing dangerous hypophosphataemia, hypokalaemia, and hypomagnesaemia. This can lead to cardiac arrhythmias, heart failure, respiratory failure, and death. Prevention is key: identify at-risk patients, start feeding low and slow (10 kcal/kg/day), give thiamine before feeding, and monitor and replace electrolytes aggressively.
Key Facts
- Mechanism: Starvation → Fat metabolism → Refeeding with carbs → Insulin → Electrolyte shift
- Key Electrolytes: Low Phosphate, Potassium, Magnesium
- At-Risk: BMI <16, Weight loss >15%, No food >10 days, Anorexia nervosa
- Prevention: Start low and slow; Thiamine before feeding; Monitor electrolytes
- Complication: Cardiac arrest, Heart failure
Clinical Pearls
"Phosphate is the Key": Hypophosphataemia is the hallmark of refeeding syndrome and can cause ATP depletion, cardiac failure, and death.
"Thiamine Before Feeding": Give IV thiamine (Pabrinex) BEFORE starting nutrition to prevent Wernicke's encephalopathy.
"Low and Slow": Start at 10 kcal/kg/day in high-risk patients and increase gradually.
"Monitor Daily": Check phosphate, potassium, and magnesium daily for the first 7-10 days.
At-Risk Groups
| Group | Notes |
|---|---|
| Anorexia nervosa | Most common cause |
| Chronic alcoholism | Wernicke's also risk |
| Cancer patients | Cachexia |
| Post-surgical patients | Prolonged fasting |
| Elderly neglect | |
| ICU patients | Prolonged starvation |
| Homeless individuals |
NICE Criteria for High Risk
One or more of:
- BMI <16 kg/m²
- Unintentional weight loss >15% in 3-6 months
- Little or no nutritional intake for >10 days
- Low levels of K, PO4, Mg before feeding
Two or more of:
- BMI <18.5 kg/m²
- Unintentional weight loss >10% in 3-6 months
- Little or no nutritional intake for >5 days
- History of alcohol abuse or drugs (insulin, chemotherapy, antacids, diuretics)
During Starvation
- Body switches from carbohydrate to fat metabolism (ketosis)
- Insulin levels fall
- Intracellular stores of phosphate, potassium, magnesium, and thiamine deplete
- Total body depletion, but serum levels may appear normal
On Refeeding
- Carbohydrate intake → Insulin release
- Insulin drives glucose AND electrolytes into cells
- Serum phosphate, potassium, magnesium plummet
- ATP production fails (needs phosphate)
- Cardiac, respiratory, and neurological dysfunction
Thiamine Deficiency
- Glucose metabolism requires thiamine
- Refeeding without thiamine → Wernicke's encephalopathy
Features of Refeeding Syndrome
| System | Features |
|---|---|
| Cardiac | Arrhythmias, Heart failure, QT prolongation, Sudden death |
| Respiratory | Respiratory weakness, Failure |
| Neurological | Confusion, Seizures, Wernicke's (if thiamine depleted) |
| Muscular | Weakness, Rhabdomyolysis |
| Haematological | Haemolytic anaemia, Platelet dysfunction |
Timing
General
- Signs of malnutrition (cachexia, muscle wasting)
- Confusion
- Tachycardia, hypotension
Cardiovascular
- Peripheral oedema (fluid retention from insulin)
- Heart failure signs
Neurological
- Wernicke's triad (if thiamine deficient): Confusion, Ataxia, Ophthalmoplegia
Electrolytes (Monitor Daily)
| Test | Expected in Refeeding |
|---|---|
| Phosphate | LOW (hallmark) |
| Potassium | LOW |
| Magnesium | LOW |
| Glucose | Elevated (insulin resistance initially) |
Other
| Test | Notes |
|---|---|
| U&Es | Sodium, Renal function |
| Calcium | May be low |
| ECG | QT prolongation, Arrhythmias |
| LFTs | May derange |
Management Approach
┌──────────────────────────────────────────────────────────┐
│ REFEEDING SYNDROME MANAGEMENT │
├──────────────────────────────────────────────────────────┤
│ │
│ PREVENTION (Key to success): │
│ │
│ 1. IDENTIFY AT-RISK PATIENTS (NICE Criteria) │
│ │
│ 2. THIAMINE BEFORE FEEDING │
│ • IV Pabrinex (Vitamins B and C) │
│ • Start 30 min before nutrition │
│ • Continue for 10 days │
│ │
│ 3. START LOW AND SLOW │
│ • 10 kcal/kg/day initially (high risk) │
│ • 5 kcal/kg/day if very high risk (BMI <14) │
│ • Increase slowly over 5-7 days │
│ │
│ 4. REPLACE ELECTROLYTES │
│ • Check PO4, K, Mg before feeding │
│ • Replace if low │
│ • Monitor DAILY for first 7-10 days │
│ │
│ 5. FLUID BALANCE │
│ • Restrict sodium initially │
│ • Monitor for fluid overload │
│ │
│ TREATMENT IF REFEEDING OCCURS: │
│ • STOP or REDUCE feeding │
│ • Replace phosphate (IV if severe) │
│ • Replace potassium and magnesium │
│ • Cardiac monitoring │
│ • Escalate to HDU/ICU if unstable │
│ │
└──────────────────────────────────────────────────────────┘
Cardiovascular
- Cardiac arrhythmias
- Heart failure
- Sudden cardiac death
Respiratory
- Respiratory failure
Neurological
- Wernicke's encephalopathy
- Seizures
- Delirium
With Prevention
- Refeeding syndrome is largely preventable
If Occurs
- High mortality if not recognised and treated
Key Guidelines
- NICE CG32: Nutrition Support for Adults
- MARSIPAN: Management of Really Sick Patients with Anorexia Nervosa
What is Refeeding Syndrome?
Refeeding syndrome is a dangerous condition that can happen when someone who has been starving starts eating again. The body's chemistry becomes unbalanced, which can affect the heart and other organs.
Who is at Risk?
- People with eating disorders (like anorexia nervosa)
- Anyone who hasn't eaten properly for a long time
How is It Prevented?
- Starting nutrition slowly ("low and slow")
- Giving vitamins (especially thiamine) before feeding
- Checking and replacing minerals like phosphate, potassium, and magnesium
Is It Serious?
Yes, it can be life-threatening if not managed properly. However, with careful monitoring and prevention, it can be avoided.
Primary Guidelines
- NICE. Nutrition Support for Adults: Oral Nutrition Support, Enteral Tube Feeding and Parenteral Nutrition (CG32). 2006. nice.org.uk/guidance/cg32
Key Studies
- Stanga Z, et al. Refeeding syndrome: illustrative cases and guidelines for prevention and treatment. Eur J Clin Nutr. 2008;62(6):687-694. PMID: 17609717