Anorexia nervosa
A 14-year-old girl presents to the emergency department after 3 months of weight loss. She has refused all food and water for the past five days. She complains of feeling dizzy, cold and tired. On examination, she has a temperature of 35.8, HR 42, BP 85/40, RR 20. Her weight is 39kg, and her height is at the 50th centile for her age. She is cold peripherally, with thin lanugo. The physical exam is otherwise normal.
Definitions
- Anorexia nervosa – body weight 15% below expected for age and height, fear of gaining weight with a distorted perception of body size, and amenorrhoea
- Bulimia nervosa – recurrent episodes of binge eating and inappropriate compensatory behaviour to prevent weight gain
- Eating disorder not otherwise specified (ED-NOS)– disturbed eating patterns that do not meet the above criteria
Epidemiology
Anorexia affects 0.5-1% of adolescent females, while 2-5% have bulimia or ED-NOS.
Risk factors
- Genetic: female sex, first-degree relative with an eating disorder or mental illness (strong predictor for young children)
- Medical: type 1 diabetes, comorbid psychiatric disorder – particularly OCD in anorexia and alcoholism in bulimia
- Social: activities which emphasise leanness, e.g. dance, modelling, wrestling; criticism of body weight from peers; unrealistic media portrayal of women
- Family: high parental expectations, difficulty managing conflict, anxiety/perfectionist traits, weight/appearance important to parents
History
- Amount of weight loss/poor gain, rate of weight loss
- Estimated dietary intake, acute food refusal
- Vomiting, use of laxatives/diuretics, excessive exercise
- Amenorrhoea, dizziness, palpitations, cold intolerance
- Thoughts around body image
- Mental health exam
Examination
- Vital signs – postural BP drop, bradycardia/tachycardia, hypothermia
- Height, weight, head circumference, pubertal status, assessment of muscle mass/fat stores – Â plot centiles and calculate BMI
- Skin – pallor, dry scaly skin, lanugo (fine, downy) hair, acne, eczematous scaling secondary to zinc deficiency
- Hair – thinning, brittle hair;Â trichotillomania
- Stigmata of purging – bruised knuckles, dental enamel erosion, markers of self-harm
- Peripheral, pretibial and sacral oedema
- Careful general examination looking for evidence of cardiac, renal or hepatic compromise, and dehydration – if shocked, may require intensive care level support
- Mental state – often significant cognitive impairment, poor reasoning, and poor emotional processing
Investigations
- Bloods – Full blood count, urea and electrolytes, glucose, creatinine, eGFR, calcium, phosphate, zinc, liver function, thyroid function, LH/FSH/oestrodiol, venous blood gas (vomiting-induced metabolic alkalosis)
- ECG –Â bradycardia, ventricular tachyarrhythmias, low voltage QRS, P and T waves, presence of U waves, and QTc prolongation (associated with increased risk of arrhythmias and sudden death)
- DEXA scan
What are the criteria for hospitalisation?
- Medical instability – Â HR <50, BP <80/50, hypothermia, hypokalemia, hypophosphataemia, hypoglycemia, neutropenia, hypoalbuminemia (rare and should prompt a search for infection), dehydration, and cardiac/renal/hepatic compromise
- Rapid weight decline, food refusal, uncontrolled bingeing/purging
- Co-morbid psychiatric emergency, particularly suicidal ideation
- Not responding to outpatient treatment
Management: requires a multidisciplinary approach.
- Weight restoration through graduated re-feeding, often starting with continuous NG feeds, aiming for a gain of 0.5-1 kg/week. Dietitian input crucial with twice-weekly weighing.
- Behavioural/ward management – bed rest initially with restricted leave; Â may require bathroom supervision; meal supervision; restricted activity; discourage parents from bringing food and medications/supplements in the early phases of recovery
- Medical – Â correct electrolyte abnormalities prior to refeeding; commence phosphate, thiamine and multivitamin supplements; daily examination and bloods until medically stable; routine DEXA; bone age in those with primary amenorrhoea
- Medications – olanzapine reduces hyperactivity and overvalued ideas
- Psychological – Â family therapy is more effective than individual therapy in the paediatric population
- Physiotherapy – to address exercise motivation, relaxation strategies, graded activity, and constipation management. Massage, yoga, and meditation may be beneficial
- Discharge – Â depending on hospital guidelines, patients may be transferred from medical to psychiatric services when medically stable. Â Patients should reach 90% of their ideal body weight prior to discharge home.
Complications
Profound medical instability is more likely in children <13 years, especially if prepubertal.
What about refeeding syndrome?
- Occurs due to electrolyte and fluid shifts due to stimulation of metabolism following refeeding. Characteristically results in hypophosphatemia, hypomagnesiumia, and hypokalemia
- Risk factors: rapid weight loss, very low body weight, low phosphate/magnesium/potassium prior to refeeding, acute food refusal
- Features: weakness, fatigue, dyspnoea, peripheral oedema, hallucinations, seizures, arrhythmias
- Management: Bed rest, multivitamins including phosphate, thiamine, and zinc, potassium replacement, reduce nutrition, cardiac monitoring
Cardiovascular effects
- Physiological bradycardia is expected; telemetry should be considered for HR <40
- A sudden increase in HR to the normal range can be a red flag of impending heart failure
- Decreased cardiac mass results in reduced exercise capacity, fatigue and occasionally mitral valve prolapse
Endocrine effects
- Hypoglycemia can occur in the early morning and post-prandially due to low glycogen stores and abnormal insulin secretion
- Sick euthyroid with normal TSH. Thyroid replacement not beneficial
- Amenorrhoea may not resolve in 10-30% despite weight gain
- Osteoporosis occurs in 30% of patients. No evidence for treatment with medications/supplements
- Young patients may not reach their height potential or peak bone mass
Gastrointestinal effects
- Gastroparesis/bloating can be managed with liquid food supplements, smaller meals, and metoclopramide
- Constipation should be managed conservatively with fluids and fibre. Laxatives are a last resort
Renal effects
- Renal impairment can occur due to electrolyte imbalances, acute kidney injury (more likely if bingeing/purging), chronic renal impairment and nephrolithiasis
- eGFR should be measured. Â Creatinine may be within the normal range when renal impairment is present in patients with low muscle mass
Haematological effects
- Cytopenias can occur; a high index of suspicion for infection is required, as fever and tachycardia may be absent
What’s the prognosis?
- The paediatric population has a better prognosis than adults.
- Early hospitalisation may prevent multiple hospitalisations and a chronic course.
- 50% good outcome, 25% intermediate, 25% poor.
- 1/5 mortality rate at two decades from medical complications or suicide.
- Predictors of poor prognosis include: very low BMI, automated vomiting, long illness duration, failed treatment, concurrent psychiatric diagnoses, and strong fears of maturing.
Selected references
Australian and New Zealand clinical practice guidelines for the treatment of anorexia nervosa. Royal Australian and New Zealand College of Psychiatrists Clinical Practice Guidelines Team for Anorexia Nervosa.
Foreman S. Eating disorders : Epidemiology, pathogenesis, clinical features and course of illness. Uptodate.com
Gavin R. Starship Hospital Anorexia guidelines
Mehler P. Anorexia nervosa in adults and adolescents: Medical complications and their management. Uptodate.com
Mehler P. Anorexia nervosa in adults and adolescents: The refeeding syndrome. Uptodate.com.
