Medical aspects of anorexia nervosa and bulimia nervosa

Eating disorders (EDs) have a lifetime prevalence of 8.4% for women and 2.2% for men. Anorexia nervosa (AN) and bulimia nervosa (BN) are commonly encountered in medical practice. The main medical issue for BN and the binge-purge subtype of AN is electrolyte disturbance associated with purging and vomiting, which untreated can be fatal. This loss of K+ and Cl− with associated hypovolaemia may lead to hypokalaemic alkalosis. Treatment is by fluid and electrolyte replacement. Damage to the upper gastrointestinal (GI) tract, including reflux oesophagitis, dental problems, aspiration and, occasionally, oesophageal rupture, can occur. In patients with the restrictive form of AN, the biggest risks are weight loss and malnutrition, which can have profound effects on the heart, gut, endocrine system and bone. Safe refeeding is essential. The risk to the person should be assessed using comprehensive, graded, multifactorial assessment tools, for example, Medical Emergencies in Eating Disorders (MEED). There is increasing evidence that patients can be safely refed at higher rates than was previously recommended, but it is important to assess the risk of refeeding syndrome and reduce the rate of refeeding if it is high. Underfeeding syndrome, where patients fail to establish an adequate intake, is equally important. It is critical to manage anorexic behaviour on the ward to prevent it from frustrating the process of refeeding and stabilisation. Using established protocols, communicating effectively with the patient and their family, and being aware of the methods that may be used to avoid weight gain is important, as is an understanding of mental health legislation if the least-restrictive measures fail. Recognising that the ED drives the behaviour of the patient and externalising the disorder, rather than blaming the patient, is important. Patients with EDs have high rates of functional GI disorders and bone problems. A multidisciplinary approach to treatment is essential.