Bulmia Nervosa

 

• Definition and presentation

  Key features:

  • Binging: eating large amount of food with a subjective loss of control.
  • Purging: starving, inducing vomiting, extreme exercise, or laxative use.
  • Preoccupation with weight control.
  • BMI >17.5.

  Other signs and symptoms:

  • Fatigue and lethargy.
  • GI: bloating, constipation, abdo pain, gastric dilatation (which carries a risk of rupture).
  • Occasional swelling of hands and feet.
  • Irregular menstruation.
  • Parotid enlargement.
  • Tetany

  Effects of repeated vomiting:

  • Dental enamel erosion.
  • Oesophagitis
  • Russell's sign: tooth mark calluses on back of hands.
  • Metabolic alkalosis.
  • Electrolyte changes: ↓Cl-,↓K+ (which may lead to arrhythmia).

  Effects of repeated laxative use:

  • Cardiomyopathy
  • Oedema
  • Metabolic acidosis.

• Risk factors

  • Demographic: 10 times commoner in women. Mean onset is 18 years.
  • Family history of bulimia.
  • Past history of anorexia nervosa.
  • Urban living.

• Investigations

  Use the SCOFF screening tool in those whom you suspect of an eating disorder.

  Measure height and weight.

  Metabolic and renal tests. Usually normal, but may show:

  • ↓K+ from vomiting or laxatives.
  • Alkalosis from vomiting, or acidosis from laxatives.
  • ↑Urea and ↑creatinine due to hypovolaemia.

• Management

  Psychological:

  • Psychoeducation for patients and families.
  • Structured eating plan with dietician input.
  • Enhanced CBT (CBT-E) is specifically designed for eating disorders. Weekly sessions for 20 weeks. Interpersonal therapy is an alternative, but takes longer. Guided self-help can be attempted first in milder cases.
  • Family therapy for children.

  Biological:

  • Pharmacotherapy can reduce binging and purging. Benefits should be apparent in first 2 weeks, otherwise they are unlikely to be appear.
  • Should be offered if psychotherapy is unavailable or ineffective.
  • 1st line: SSRI, high-dose fluoxetine (60 mg) or sertraline.
  • 2nd line: venlafaxine.
  • Continue for at least 12 months if effective.

  Managing purging behaviours:

  • Monitor electrolytes if they are using large amounts of laxatives. Encourage them to stop, and inform them that they have little effect on caloric intake as they mainly act on the large bowel, after most calories are absorbed.
  • Regular dental reviews if they vomit regularly. Advise to rinse with non-acid mouthwash after vomiting but avoid immediately brushing.

• Prognosis

  • 50% recover.
  • 30% follow relapsing remitting course.
  • 20% remain chronic.