Anorexia Nervosa

Related Subjects: |Depression |Mania |Schizophrenia |Suicide |Obsessive-Compulsive disorder |Wernicke Korsakoff Syndrome |Medically Unexplained symptoms |Cotard Delusion |Anorexia Nervosa

⚖️ The hallmark of anorexia nervosa is a persistent refusal to maintain even low-normal body weight, driven by an intense fear of weight gain and a distorted body image. It is a psychiatric disorder with profound systemic consequences.

📊 Epidemiology

• Prevalence: ~1 in 200 individuals.
• High mortality: ~5% per decade (often due to cardiac arrhythmia or suicide).
• More common in cultures where thinness is highly valued and among adolescent females.

🧾 Diagnostic Criteria (DSM-IV/5)

• Body weight <85% of expected for age/height (or BMI < 17.5 kg/m²).
• Intense fear of weight gain despite being underweight.
• Distorted body image or denial of illness severity.
• (DSM-IV) Amenorrhoea: ≥3 missed menstrual cycles (criterion removed in DSM-5).

📌 Summary

• Weight control behaviours: dieting, excessive exercise, purging, vomiting, diuretics, laxatives.
• Overlap with bulimia nervosa is common; patients may switch subtypes.
• Past trauma (including sexual abuse) may be a contributing factor – approach sensitively in therapy.

❤️ Cardiac & Arrhythmias

• Risk of torsades de pointes due to hypokalaemia, hypomagnesaemia, and prolonged QT interval.
• Bradycardia, hypotension, syncope are frequent findings.
• ⚠️ Avoid QT-prolonging drugs (e.g. macrolides, antihistamines, certain antipsychotics).

🔎 Types of Anorexia Nervosa

• Restricting type: Weight loss achieved by dieting, fasting, or excessive exercise; no regular purging.
• Binge-eating/purging type: Regular use of self-induced vomiting, laxatives, diuretics, or enemas.

🧪 Investigations

• Electrolytes: ↓ K⁺, Cl⁻, Ca²⁺, Mg²⁺, PO₄³⁻ → muscle weakness, arrhythmias, heart failure.
• Nutritional deficiencies: ↓ zinc, albumin, Hb, WCC, glucose, T3, LH/FSH; ↓ bone mineral density → osteoporosis risk.
• Other abnormalities: ↑ AST/ALT, ↑ amylase, ↑ cholesterol, ↑ cortisol, ↑ GH; hypochloraemic alkalosis; hypercarotinaemia.
• Imaging: CT brain may show cerebral “pseudo-atrophy,” reversible with nutrition.

👀 Clinical Features

• Severe weight loss, low BMI, loss of muscle bulk.
• Physical signs: hypothermia, lanugo hair, dependent oedema, bradycardia, neuropathy.
• Bulimic overlap: dental caries, halitosis, parotid enlargement.

⚠️ Poor Prognostic Indicators

• Prolonged illness duration.
• Severe weight loss or very low BMI.
• Older age at onset.
• Bulimic features, comorbid personality disorder, or significant relationship difficulties.

Cases — Anorexia Nervosa

• Case 1 — Adolescent onset 👩‍🎓: A 16-year-old girl presents with progressive weight loss, amenorrhoea, and excessive exercise. BMI 15.2 kg/m². Exam: lanugo hair, bradycardia (HR 44), and hypotension. She denies bingeing or purging but has intense fear of weight gain. Diagnosis: restrictive anorexia nervosa. Admitted for medical stabilisation and psychological therapy.
• Case 2 — Binge–purge subtype 🤮: A 20-year-old university student with BMI 16.0 reports cycles of strict dietary restriction followed by binge eating and self-induced vomiting. She uses laxatives regularly. Exam: dental enamel erosion, calluses on knuckles (Russell’s sign), and hypokalaemia on bloods. Diagnosis: binge–purge anorexia nervosa. Managed with electrolyte correction, CBT-E, and dietetic support.
• Case 3 — Severe medical complications ❤️: A 24-year-old woman with long-standing anorexia is admitted after a syncopal episode. BMI 13.5. Exam: peripheral oedema, prolonged QTc on ECG, and electrolyte disturbances (low potassium, phosphate). Diagnosis: anorexia nervosa with severe medical risk. Managed with cautious nutritional rehabilitation, phosphate supplementation, and continuous cardiac monitoring.

Teaching Point 🩺: Anorexia nervosa is a psychiatric disorder with systemic consequences. Hallmarks: low BMI, fear of weight gain, body image disturbance. Complications include amenorrhoea, osteoporosis, electrolyte imbalance, and sudden cardiac death. Management requires a multidisciplinary approach: medical stabilisation, psychotherapy, and nutritional rehabilitation.