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CDHB

Eating Disorders

General comments

When patients with eating disorders (anorexia nervosa, bulimia nervosa, and eating disorder not otherwise specified) are medically unstable they may require medical admission. The most common causes of admission will be complications of malnutrition or the refeeding syndrome.

Common presenting complaints include:

• Acute medical complications of malnutrition: syncope, seizures/confusion, pancreatitis, cardiac failure, gastric dilatation.
• Dehydration.
• Symptomatic hypoglycaemia (<2.5 mmol/L).
• Physiological instability:
  • Bradycardia - heart rate <50/min.
  • Hypotension - systolic BP <80 mm Hg.
  • Hypothermia - temp <35.5°C.
  • Significant postural drop in BP (>20 mm Hg) or rise in heart rate (increase by > 30 bpm).
• Electrolyte imbalance:
  • Hypokalaemia (<2.5 mmol/L).
  • Hypophosphataemia (<0.5 mmol/L).
• Haematology:
  • Symptomatic anaemia.
  • Pancytopaenia.
• Abnormal ECG:
  • Arrhythmia.
  • Diminished amplitude of QRS complex and T waves.
  • Prolonged QTc (>450).
• Arranged admission for refeeding that requires medical management (in conjunction with Eating Disorders Team Physician).

Management

• All patients with heart rate less than 40, QTc >500, arrhythmia, or potassium <2.5 should be on bed rest, and telemetry.
• For all patients requiring admission, give:
  • Thiamine 200 mg BD, IV, IM or PO.
  • Vitamin B Complex 2 tabs PO BD. This preparation contains vitamins B1, B2, B3, and B6.
  • A multivitamin preparation once daily.
• If confused, drowsy or signs of Wernicke’s encephalopathy, give:
  • Thiamine 400 mg IV or IM TDS for 2 days and then 200 mg daily IV or IM for a further 5 days.
  • Vitamin B Complex 2 tabs PO BD. This preparation contains vitamins B1, B2, B3, and B6.
  • A multivitamin preparation once daily.
• Avoid over-treating hypoglycaemia, as any glucose level above physiological will worsen the refeeding syndrome by stimulating insulin release. This will drive consumptive loss of phosphate and thiamine and glucose, and intracellular shifts of potassium and magnesium.
• Rehydrate and correct any electrolyte imbalance. Avoid IV glucose pre thiamine.
• Do not use a Bair Hugger for hypothermia as this will increase metabolic rate and cause peripheral vasodilation, and may worsen physiological instability.
• Contact the Eating Disorders Team (Physician and Eating Disorders Liaison Nurse) and consult the ward Dietitian to establish a feeding plan as soon as possible, to avoid delays in establishing adequate nutrition.
• Patients may require nasogastric feeding in the initial phase of treatment if unstable with the refeeding syndrome. General principles of nasogastric feeding include: starting slowly and gradually increasing feed rates to target over 2-3 days to control the refeeding syndrome. When on nasogastric feeding all nutrition should be through the nasogastric tube and the patient should not eat extra food (unless symptomatic hypoglycaemia occurs). Once stable at target caloric intake, the nasogastric tube can be spigoted and transition to oral nutrition should occur. This may require the Eating Disorders Team support if the patient is struggling.
• Routine daily cares in addition to standard care should include daily electrolytes (request Na, K, Ca, PO₄, Mg), ECG, and lying and standing blood pressure and pulse.
• On admission also consider:
  • Creatine kinase, looking for evidence of excessive exercise.
  • LH/FSH, oestradiol, TSH and T4, looking for evidence of hypothalamic dysfunction.
  • Beta-hydroxybutyrate, looking for evidence of starvation related ketoacidosis (increased risk with co-existent alcohol abuse).
  • LFTs are commonly deranged.

Reference: CDHB Department of General Medicine - Green Book.

Topic Code: 72808