Refeeding Syndrome

OVERVIEW

• Refeeding Syndrome = a group of clinical findings that occur in severely malnourished individuals undergoing nutritional support.
• underecognised
• occurs in the setting of prolonged starvation followed by provision of nutritional supplementation from any route.
• chronic malnutrition leads to protein catabolism with total body phosphate depletion despite normal serum phosphate
• introduction of carbohydrates leads to an anabolic state which unmasks total body phosphate depletion and leads to precipitous drop in serum phosphate
• insulin + glucose = massive uptake of phosphate, K+ and Mg2+ into cells

RISK FACTORS – anyone who may be malnourished:

Decreased intake

• eating disorders (especially anorexia nervosa)
• alcoholism
• depression
• fasting
• vomiting
• dysphagia
• chemotherapy
• prolonged NBM
• post-operative
• chronic malnutrition

Decreased absorption

• Oncology patients
• Postoperative patients
• Elderly patients (comorbidities, decreased physiological reserve)
•  uncontrolled diabetes mellitus (electrolyte depletion, diuresis)
• chronic malnutrition:
  • marasmus
  • prolonged fasting or low energy diet
  • morbid obesity with profound weight loss
  • high stress patient unfed for >7 days
• Long term users of antacids (magnesium and aluminium salts bind phosphate)
• Long term users of diuretics (loss of electrolytes)

Decreased absorption

• Malabsorptive syndrome (such as inflammatory bowel disease, chronic pancreatitis, cystic fibrosis, short bowel syndrome)

Increased catabolism

• inflammatory process (infectious and non-infectious)
• cancer

CLINICAL FEATURES

• CVS: arrhythmia, HT, CHF
• GI: abdo pain, constipation, vomiting, anorexia
• MUSC: weakness, myalgia, rhabdomyolysis, osteomalacia
• RESP: SOB, ventilator dependence, respiratory muscle weakness -> requiring intubation and ventilation
• NEURO: weakness, paraesthesia, ataxia, delirium, coma, central pontine myelinosis, seizures, Korsakoff syndrome or Wernicke encephalopathy (confusion, ataxia, ophthalmoplegia)
• METABOLIC: infections, thrombocytopaenia, haemolysis, anaemia
• HAEM: reduced 2,3 DPG production -> left shift of oxyHb dissociation curve
• OTHER: ATN, Wernicke encephalopathy, liver failure

INVESTIGATIONS

• hypophosphataemia
• hypokalaemia
• hypomagnesaemia
• hyperglycaemia
• thiamine deficiency (erythrocyte transketolase or thiamine level)
• trace elements deficiencies

MANAGEMENT

Summary of Management

(1) recognize patients at risk
(2) provide adequate electrolytes, vitamin (thiamine, water and fat soluble) and micronutrient (Zn, Fe, Se) supplementation
(3) careful fluid resuscitation to avoid fluid overload
(4) cautious and gradual energy restoration
(5) monitoring of critical laboratory indices

Resuscitate

• A – may need intubation for encephalopathy and bulbar dysfunction with aspiration
• B – ventilation because of respiratory muscle weakness with hypercapnic respiratory failure
• C – correction of electrolytes c/o arrhythmias, cautious slow volume resuscitation, central access and invasive monitoring if haemodynamically unstable
• D – may have profound weakness, cerebellar dysfunction, delirium and coma -> responds to slow correction of electrolytes

Electrolyte abnormalities + Acid Base Disturbance

• Hypophosphataemia
• Hypokalaemia (<3.5mmol/L) – replace IV or PO
• Hypomagnesaemia (<0.7mmol/L) – replace IV or PO
• Hyponatraemia – don’t correct rapidly unless symptomatic (less than 10mmol/L/day)
• Hyperglycaemia – monitor -> insulin if required

Supportive care and monitoring

Underlying cause

• screen those at risk

Feed

• 100mg/day
• Vitamin B6 (pyridoxine) – 1.7mg/day
• Vitamin B12 (cobalamin) – IM injection
• Folate – 400mcg/day
• Fat soluble vitamins – DEKA – can be replaced via feed

Micronutrients

• Selenium – 100-400mcg/day LD -> 20-70mcg/day
• Zinc – 10-30mg/day LD -> 2.5-5mg/day
• Iron – no loading dose required -> 10mg/day PO

Disposition

• managed in an HDU/ICU environment if severe

References and Links

• Khan LU, Ahmed J, Khan S, Macfie J. Refeeding syndrome: a literature review. Gastroenterol Res Pract. 2011;2011. PMC2945646.
• Mehanna HM, Moledina J, Travis J. Refeeding syndrome: what it is, and how to prevent and treat it. BMJ. 2008 Jun 28;336(7659):1495-8. PMC2440847.