Adolescence is defined by the World Health Organization as the period between 10 and 19 years, heralded by pubertal changes. Puberty is a highly programmed and biologically driven process that affects behaviour, emotional wellbeing and health. 

Introduction

The marketing of unhealthy products and lifestyles (eg. alcohol, tobacco and foods high in fat, sugar and salt) clearly targets young people. With increased pricing and tightening policy change, adolescent smoking has declined in the past 15 years. However, a major concern is the rise in female smoking. The expanded social environment provided by new forms of social media has been firmly embraced by adolescents. However, adolescents are susceptible to the physical effects of intense engagement with social media such as decreased physical activity and sleep disturbance, cyberbullying and exposure to pornography, and new behaviours such as sexting (sending sexually explicit messages or photographs by mobile phone). 

Copycat suicides are now more likely in view of the power of new media to emotionally and graphically publicise suicides. Social media has great potential to be used in health promotion to adolescents. Safe and supportive families, supportive schools and positive and supportive peers are all crucial to help adolescents to attain their full potential. The strongest determinants of adolescent health are national wealth, income inequality and access to education. Best outcomes are likely in countries with less income inequality and excellent access to secondary and tertiary education (eg. Norway). Gun control and road safety policies are very important to reduce morbidity and mortality in adolescence.

Eating disorders and management

Up to one in 200 adolescent girls have anorexia nervosa and between 1-2% have bulimia. It may also affect males, younger children and adults. There is a strong genetic component for anorexia nervosa and genetic effects seem to be ‘activated‘ by the onset of puberty. Dieting is also implicated in the later development of anorexia nervosa. Physical hyperactivity is a common feature which may manifest as compulsive exercise, and this hyperactivity seems to be mediated by leptin. Anorexia nervosa is associated with significant morbidity and mortality. Five per cent die from anorexia and 20% progress to chronic eating disorders. 

Death from suicide is 50 times more likely in patients with anorexia nervosa and 25-35% of bulimia patients report a history of attempted suicide or self-harm. 

Diagnostic criteria (adapted from DSM-IV)

• Refusal to maintain weight with a body weight of 85% or less than that expected
• Intense fear of gaining weight or becoming fat even though underweight
• Amenorrhoea in post-menarchal females
• Altered body image with undue influence of body weight or shape on self-evaluation 
• With bulimia, recurrent inappropriate behaviour to prevent weight gain such as self-induced vomiting, fasting, misuse of laxatives or excessive exercise. 

Key points in the history

Medical professionals should ask pointed questions about the patient’s desired weight (“what would you like to weigh?”), their exercise routine, current eating habits, whether binge eating or any history of self-induced vomiting. Ask for a family history, in particular, of obesity, eating disorders, other mental illness. Take a menstrual history. Ask about symptoms such as syncope, cold intolerance, dry skin or hair loss. 

Examination 

Look for bradycardia or orthostatic changes in the pulse rate (> 20 beats per minute) or blood pressure (> 10mmHg). Look for cachexia, facial wasting and dull, thinning scalp hair. Affect may be flat and anxious and extremities may be cold or oedematous. Look for delayed or interrupted pubertal development. 

Red flags

• Body mass index (BMI) < 13kg/m²
• > 1kg weight loss in one week
• Below second centile on BMI chart
• Blood pressure < 80/50 or orthostatic hypotension (10-20mmHg drop on standing)
• Pulse < 40 per minute
• Cold peripheries or hypothermia < 34.5°C
• Electrolyte abnormalities (potassium < 2.5mmol/l, sodium < 130mmol/l or phosphate < 0.5mmol/l 
• Prolonged QT interval on ECG.

Admission to hospital should be reserved for patients with complications of extreme malnutrition,  those determined at risk for re-feeding syndrome, those in whom outpatient treatment is failing or younger children. Medical management should take place alongside psychiatric treatment.

Differential diagnoses of eating disorders

Inflammatory bowel disease, coeliac disease, panhypopituitarism, Addison’s disease, hyperthyroidism and hypothyroidism and central nervous system (CNS) tumours involving the hypothalamus.

Investigations 

Initial laboratory assessment should include full blood count,  urea and electrolytes, glucose, calcium, magnesium and phosphate, liver function tests (LFTs) and thyroid function tests (TFTs). An ECG should be performed looking for QT interval prolongation. 

Management

The goals of management are stabilisation of vital signs, electrolyte correction, nutritional rehabilitation and motivation for recovery. The multidisciplinary team should review the treatment plan on a regular basis and clear boundaries should be set. 

Oral feeding is the preferred route for re-feeding. Continuous NG feeding may be required if caloric intake is insufficient. Weight should be regularly measured and patients should be monitored for signs of purging. Excessive exercise should be discouraged. Suggested target weight gains should be 0.5 to 1.0 kg per week. A balanced diet should be provided including 45-65% carbohydrate, 10-35% protein and 20-35% fat. Calcium intake should be 1200-1500mg per day. 

Patients should take daily multivitamin and iron supplements. Family-based interventions are important. Drug therapy is rarely indicated but selective serotonin reuptake inhibitors (SSRIs) may be helpful if symptoms of anxiety or depression. Fluoxetine has been shown to decrease binge eating and purging in bulimia patients. Topiramate has been also shown to reduce binge eating. Re-feeding syndrome occurs acutely in severely malnourished patients when feeding is started. The key biochemical abnormality is hypophosphataemia but hypoglycaemia, hypomagnesaemia and salt and water retention may occur. Key features of re-feeding syndrome are:

• Fluid overload with cardiac failure
• Muscle weakness
• Diarrhoea
• Delirium, hallucinations and a depressed level of consciousness 
• Electrolyte imbalance. 

To avoid re-feeding syndrome, keep initial caloric intake low, closely monitor gradual increase with dietetic supervision, monitor fluids and electrolytes and give multivitamin and thiamine supplements.  

Medical complications of anorexia nervosa 

Cardiac 

Malnutrition causes cellular changes within cardiac muscle leading to hypertrophy and reduced cardiac output. QT prolongation occurs in up to 15% of patients. Orthostatic hypotension is common and may lead to syncope. Most cardiac complications improve with re-feeding.

Fluid and electrolyte disturbance

Blood urea rises but creatinine remains low due to low muscle mass. Hypomagnesaemia and hypophosphataemia may both lead to muscle weakness. Hypokalaemia can lead to poor gut motility, myopathy and arrhythmias. Profound hyponatraemia can lead to seizures. 

Gastrointestinal

Increased risk of dental caries and oesophagitis.

Haematological

There may be a low neutrophil count with reduced cell-mediated immunity and complement activity, all increasing the risk of infection. Normochromic anaemia may occur, as may pancytopenia in severe cases.

Neurological

Neurological changes include poor concentration, apathy, muscle weakness and muscle cramps due to myopathy. MRI scans may show a degree of white matter changes generally correlating with the degree of malnutrition. 

Follow-up management

Patients with an earlier age of onset, shorter duration of symptoms and a better parent-child  relationship have a better prognosis. Purging behaviour, physical hyperactivity and more significant weight loss are all associated with a less favourable prognosis. Even after recovery, depression and anxiety symptoms may persist. 

Conclusion

Anorexia nervosa is characterised by sustained deliberate weight loss with secondary endocrine or metabolic change. Classical symptoms and signs should be looked for. Most can be managed in an outpatient setting but a multidisciplinary approach is required.