Anorexia Nervosa
Definition | Aetiology | Pathophysiology | Risk factors | Signs and symptoms | Investigations | Management
Definition
Anorexia Nervosa is an eating disorder characterised by an intense fear of gaining weight, distorted body image, and persistent restriction of food intake, leading to significantly low body weight and nutritional deficiencies.
Aetiology
- Genetic factors: familial predisposition to eating disorders and mood disorders.
- Neurobiological factors: serotonin and dopamine dysregulation affecting appetite and impulse control.
- Psychosocial factors: perfectionism, low self-esteem, and societal pressure regarding body image.
- Environmental factors: childhood trauma, bullying, or exposure to media promoting thinness.
Pathophysiology
- Hypothalamic-pituitary dysfunction leading to hormonal imbalances (e.g., amenorrhoea due to low oestrogen).
- Altered serotonin pathways affecting mood, satiety, and anxiety regulation.
- Increased ghrelin levels due to prolonged caloric restriction.
- Cardiac atrophy and bradycardia due to prolonged malnutrition.
Risk factors
- Family history of eating disorders or obsessive-compulsive traits.
- Personality traits such as perfectionism, rigidity, and high self-criticism.
- Exposure to environments with a strong emphasis on weight control (e.g., ballet, modelling, athletics).
- History of dieting or restrictive eating patterns.
- Psychiatric comorbidities such as depression, anxiety, or OCD.
Signs and symptoms
- Severe weight loss and low BMI (<18.5 kg/m²).
- Intense fear of gaining weight despite being underweight.
- Distorted body image with persistent belief of being overweight.
- Amenorrhoea or irregular menstruation in females.
- Bradycardia, hypotension, and cold intolerance.
- Lanugo (fine body hair) due to hypothermia.
- Dry skin, brittle nails, and hair thinning.
- Osteopenia or osteoporosis due to chronic malnutrition.
Investigations
- Clinical assessment: full eating disorder history, including dietary intake and exercise patterns.
- Screening tools: SCOFF questionnaire, Eating Disorder Examination Questionnaire (EDE-Q).
- Blood tests: U&Es, FBC, LFTs, TFTs, glucose, lipid profile, calcium, phosphate.
- ECG: to assess for bradycardia and prolonged QT interval.
- Bone density scan (DEXA): to assess for osteoporosis if prolonged malnutrition.
Management
1. Psychological therapies:
- Cognitive Behavioural Therapy for Eating Disorders (CBT-E) as first-line treatment.
- Maudsley Family-Based Therapy (FBT) for adolescents.
- Motivational interviewing to enhance treatment engagement.
2. Nutritional rehabilitation:
- Structured meal plans to restore weight gradually.
- Monitoring for refeeding syndrome with careful electrolyte correction.
- Dietitian-led guidance on balanced nutrition.
3. Pharmacological management:
- SSRIs (e.g., fluoxetine) if comorbid depression or OCD is present.
- Avoid bupropion due to increased seizure risk.
- Consider olanzapine for severe weight gain resistance.
4. Medical stabilisation:
- Inpatient admission if BMI <15 kg/m², severe electrolyte imbalances, or high suicide risk.
- Monitoring for cardiovascular complications and bradycardia.
5. Referral:
- Specialist eating disorder services: for multidisciplinary support.
- Dietitian: for nutritional rehabilitation.
- Psychiatrist: if severe psychiatric comorbidities or treatment resistance.