Anorexia Nervosa

People with anorexia nervosa maintain a low body weight as a result of a preoccupation with weight, construed as either a fear of fatness or a pursuit of thinness

Aetiology

  • Higher incidence in females
  • Highest incidence 15-19 years

Clinical presentation

  • Eating over-controlled, possibly binge and purge behaviours
  • Exercise usually obsessive
  • Relationships often isolated, usually conflict-avoidant
  • Common traits: anxious, obsessional, risk avoidant, may avoid independence

Investigations

  • An ESR and TFTs are useful screens for other causes of weight loss
  • Other tests will depend on the individual presentation
  • MARSIPAN/MARSIPAN junior scoring system can be used to assess physical risk

Management

Under 18 years

  • First line - anorexia-nervosa-focused family therapy
  • If patient is severely ill (severe malnutrition, very low BMI etc.), inpatient treatment may be required

Adults

  • Psychological treatment options include:
    • Individual eating-disorder-focused cognitive behavioural therapy (CBT-ED)
    • Maudsley Anorexia Nervosa Treatment for Adults (MANTRA)
    • Specialist supportive clinical management (SSCM)
  • If patient is severely ill (severe malnutrition, very low BMI etc.), inpatient treatment may be required

Complications - refeeding syndrome

  • Potentially fatal metabolic response to too rapid re-feeding after a period of starvation

Pathophysiology

  • Most at risk - severely underweight, rapid weight loss, or minimal intake in preceding 7-14 days
  • Body switches from carbohydrate to fats and protein as its energy source
  • Intracellular minerals become depleted but serum levels may remain normal
  • Re-feeding stimulates insulin production which causes potassium/magnesium and phosphate to be taken into cells whilst serum levels fall
  • The rapid change in BMR together with serum electrolyte depletion causes the physical syndrome of re-feeding syndrome

Management

  • Be aware of the risk
  • Start with low level energy replacement, with high phosphate content e.g. milk, and build up every 2-3 days
  • Supplement with multivitamin e.g. forceval and thiamine for at least 10 days
  • Daily monitoring of bloods
  • Correct electrolyte and fluid imbalances e.g. phosphate sandoz, sando K
    • IV replacement may be necessary but careful monitoring of bloods and patient's physical presentation should allow early treatment