Eating disorders are abnormalities in eating habits, in the context of a person’s distorted view of their body image. The common subtypes are anorexia nervosa (AN) and bulimia nervosa (BN). There is overlap in the symptom pattern. Some sufferers may have a clinical picture that is initially consistent with AN but becomes consistent with BN after a period of time. If all the diagnostic criteria are not fully met, the terms ‘atypical anorexia’, ‘atypical bulimia’ or ‘unspecified eating disorder’ may be used to describe the condition. The following article gives information about AN. Please refer to our separate article for [more information on BN](http://behindthemedicalheadlines.com/articles/eating-disorders-bulimia-nervosa). ####How common is anorexia nervosa? The prevalence of AN is 0.3% (three in 1,000) of young women,[1] and 80–90% of sufferers are women.[1] Anorexia nervosa has also been identified in non-Western societies.[2] ####Common myths * ‘Anorexia nervosa only affects women.’ In reality, up to 10% of people with AN are men. * ‘Anorexia nervosa only affects teenage girls.’ Anorexia nervosa is more common in younger age but can develop in all ages. * ‘Anorexia nervosa is a disorder of a higher social class.’ In reality, eating disorders are not shown to be more prominent in any particular social class,[3] but those that attend treatment tend to be from a higher social class. * ‘Anorexia nervosa is caused by families.’ In reality, lots of problems or difficulties in families arise due to looking after a person with AN. A study looking at family functioning in families with an AN or cystic fibrosis sufferer revealed that both groups showed higher emotional over-involvement than households who did not have sufferers of a chronic condition.[4] * ‘Anorexia nervosa is caused by trying to be thin, or is due to dieting that has gone out of control.’ In reality, the cause of AN is probably multifactorial. The majority of people that go on a diet do not develop AN. * ‘Anorexia nervosa is not serious.’ Anorexia nervosa can be difficult to treat, and can be life-threatening. Anorexia nervosa causes the highest mortality rate within psychiatric disorders. It is a serious condition. * ‘People with AN do not like food.’ In reality, people with AN are often preoccupied with food. They may spend lengthy periods of time preparing food for others, but do not eat a lot themselves. ####What causes it? The cause of AN is probably multifactorial. Anorexia nervosa can be found in families with obsessive, perfectionist and competitive traits. However, within the same family, there can be members that are affected by AN and others that are not. This implies that a genetic predisposition makes people more vulnerable to develop AN but that other factors also play a role. Common stressors that may precipitate AN are the onset of puberty, transitions, family conflict, academic pressures and other factors.[1] Media influences may also play a part in affecting people’s perception of body image but are not the whole story. ####Why is it important to recognise and treat AN? Anorexia nervosa causes the highest mortality rate within psychiatric disorders. It is associated with premature death (standardised mortality rate of 3.3).[5] It also causes a high morbidity in physical, psychological and social well-being. There is a higher risk of death if there are more weight fluctuations, a very low body mass index (BMI), purging or concurrent substance misuse, including alcohol.[1,5] ####Diagnosis People with AN often try to hide their symptoms from family or friends, so initially it may be hard for others to notice the illness. Anorexia nervosa is characterised by a distorted body image of oneself. Sufferers impose a low weight threshold on themselves. They dread being fat or putting on weight. They self-induce weight loss by different methods, for example avoiding food that they deem to be ‘fattening’; restricting the quantity of food they eat; purging with laxatives; the use of appetite suppressants, diuretics or slimming pills; excessive exercise; or self-induced vomiting. The body weight of people with AN is at least 15% below expected, or the BMI is 17.5 or less.[6] The hypothalamic-pituitary-gonadal axis is affected; this manifests in women as amenorrhoea (lack of menstruation) and in men as a loss of sexual interest and potency. Anorexia nervosa may cause delayed puberty, failure to achieve target height and osteoporosis.[7] The severity of AN is indicated by low or rapidly falling BMI and physical complications. In children, the use of BMI is less reliable than calculating the expected weight for a child’s height. Anorexia nervosa may present with depression, obsessive behaviour, amenorrhoea, infertility and gastrointestinal symptoms.[1] Sufferers may present to gastroenterologists or gynaecologists. It is important to recognise that AN sufferers can become pregnant even when they are amenorrhoeic or when they have a low BMI. Weight gain and body shape changes during pregnancy can provoke extreme distress in those with AN. There is also a higher prevalence of eating disorders and sub-threshold eating disorders in those with insulin-dependent diabetes.[8] Starvation alone can lead to physical and psychological symptoms. In a study using healthy volunteers, starvation led to many physical and psychological symptoms similar to those experienced by people with AN.[9] ####Referral It is very important to prepare patients prior to a referral, to improve the attendance rate. Referrals should be made to the nearest eating disorder service. The referrer should provide height, weight (ideally at least two weights over time to show the rate of weight change) and recent blood results. If an eating disorder service is not available locally, referrals should be made to a mental health service. A referral to a dietician with expertise in eating disorders should also be made. ####Investigations The following investigations should be made: * Height and repeated weights; * A thorough physical examination (look for skin breakdown and purpuric rash; check for erect and supine blood pressure, pulse, temperature; perform cardiovascular, respiratory, gastro-intestinal and neurological examinations); * Sit up and squat tests (is the person with AN able to sit up without using their arms as leverage? Is the patient able to squat and get up without using their arms for balance?); * Blood tests (full blood count, urea and electrolytes, calcium, albumin, magnesium, phosphate, liver function tests, creatine kinase, glucose, erythrocyte sedimentation rate, thyroid function tests, vitamin B12 and folate); * Electrocardiogram (look for QT interval, arrhythmias or changes associated with abnormal electrolytes); * A bone scan may be needed to look for osteoporosis. ####Treatment The management of AN is complex and often requires a multidisciplinary approach. People with AN should be advised against harmful activities such as purging, or activities that consume energy, such as exercising. Most treatment takes place in the outpatient setting. This usually involves gradual refeeding with dietician input, psychotherapy and medical assessments of the patient’s physical state. Weight gain is aimed at 0.5 kg per week in the outpatient setting, and 0.5–1 kg per week in the inpatient setting.[10] People with AN often have bradycardia, low white cell count and neutropenia. They are more at risk of infections when they have a low white cell count. However, those with a low white cell count do not always require hospital admission since there is a risk of hospital-acquired infections. White cell counts improve with refeeding and weight gain. Infections should be treated vigorously without delay. There are many types of psychotherapies that may be useful for AN, with no clear evidence-based best treatment. Commonly used types of psychotherapy are cognitive-behavioural therapy, interpersonal therapy, cognitive analytical therapy and family therapy.[10] Patients may need to be hospitalised if there are physical complications. Sometimes the use of Mental Health Act legislation may be required to detain patients when the situation is life-threatening, if they are not willing to engage in treatment voluntarily or if they do not make progress with outpatient treatment. ####Complications People with AN may suffer from the following complications: * Electrolyte disturbance (for example, low potassium) from purging; * Neurological complications, such as fits from purging; * Cardiac complications, such as arrhythmias due to prolonged corrected QT interval from low weight, exacerbated by deranged electrolytes; * Overwhelming infection secondary to a compromised immune system, due to low neutrophil count; * Dental erosion from self-induced vomiting; * Osteoporosis; * Renal failure; * Hypothermia; * Death. ####Illness course and prognosis Treatment is lengthy. Fifty per cent of patients do not recover completely and have a fluctuating course.[11,12,13] Recovery can take six years from the time of diagnosis.[11,12] Anorexia nervosa is usually managed in the outpatient setting. However, for those who are very ill with complications, hospital admissions can be life-saving. ####Advice to family members or carers Family arguments often happen surrounding the symptoms of AN and the difficulties caused by condition. It is important to get involved in the care plan of the person with AN, and provide firm and assertive care together. Do bear in mind that recovery can take years. ####Useful links * Royal College of Psychiatrists. [Eating disorders](http://www.rcpsych.ac.uk/mentalhealthinfoforall/problems/eatingdisorders/eatingdisorders.aspx) (an information leaflet on anorexia and bulimia) * Quality Improvement Scotland. [Eating disorders in Scotland – recommendations for management and treatment]( http://www.nhshealthquality.org/nhsqis/qis_display_findings.jsp?pContentID=3255&p_applic=CCC&p_service=Content.show) * National Institute of Clinical Excellence. [*Eating disorders: core interventions in the treatment and management of anorexia nervosa, bulimia nervosa and related eating disorders.*](http://www.nice.org.uk/CG009) * Self help websites: [Beat eating disorders](http://www.b-eat.co.uk) (B-EAT) and [Disordered eating](www.disordered-eating.co.uk/) 2009-10-01T13:02:09Z Dr Wong has received funding from Wyeth for the research project 'Functional Imaging Biomarkers of Cognitive Enhancer Efficacy', led by Prof. Stephen Lawrie. 115 2009-10-01T00:00:00Z 2009-10-19T08:51:51Z eating-disorders-anorexia-nervosa 2009-10-19T08:51:51Z

Anorexia nervosa is an eating disorder characterised by a distorted body image, resulting in a self-imposed low-weight threshold. In the first of two linked articles on eating disorders, Drs Dichelle Wong and Katharine Logan review this serious and potentially life-threatening illness, and discuss common myths surrounding the condition, as well as its causes, diagnosis, treatment and prognosis.

2009-10-19T08:51:51Z