Case
A 20 year old lady comes to see the GP as she has not menstruated for some time. She has always been of slim build but over the last few years her weight has gradually reduced, and although she recognises that she is underweight, she does not believe that this is a problem. On questioning, there is evidence of calorie counting, food group restriction and excessive exercise. She describes no problems with her physical health. The GP decides to measure her BMI and notes it as 15.5kg/m2.
The problem
The WHO defines anorexia nervosa as an eating disorder ‘characterised by deliberate weight loss, induced and sustained by the patient’.1 It has an increased mortality rate when compared to other eating disorders and the subtype where the dominant method of weight loss is diet restriction and excessive exercise (‘restrictive’ subtype) is diagnosed most frequently. 2 The other subtype, ‘binge-eating/purging’, is also seen and often there is an overlap. The overall lifetime prevalence rate is reported to be in the range of 0.5 to 1%, although this is lower in males.3 There is also evidence that, while not meeting full diagnostic threshold, disordered eating is seen with greater frequency in the adolescent population.
Its etiology is multifactorial but the disorder is characterised in most by a persistent, intrusive and overvalued fear of gaining weight or of fatness. A number of predisposing factors have been identified including being female, the presence of certain personality traits including obsessive and perfectionistic traits, perceptual abnormalities in how sufferers view themselves physically and having previously been overweight, although this list is not exhaustive.4 It is, however, the interaction of such factors that lead to the development of the disorder in an individual. Often, anorexia nervosa manifests itself in adolescence or early adulthood, with it being postulated that the challenge of moving away from being dependent on one’s parents and being more autonomous may play a role for some.
Diagnosis and clinical features
ICD-10 diagnostic criteria include weight loss, or in children a lack of weight gain, leading to a body weight of at least 15% below the normal. In adults this is usually represented by a BMI <17.5 kg/m2.1 Weight loss is self-induced via intake restriction and is secondary to a self-perception of being too fat, with an intrusive dread of fatness, leading to a self-imposed low weight threshold. There is an associated endocrine disturbance, which presents as amenorrhoea in females and loss of sexual interest and potency in males. There may also be evidence of the use of other methods to restrict weight such as self-induced vomiting or purging, excessive exercise, use of appetite suppressants or diuretics.
Other psychological features may be present, including viewing weight loss as an achievement, difficulty recognising the extent and seriousness of the problem and its consequences, and ambivalence regarding change. Sufferers may have little insight and a reluctance to engage with health services. These factors may lead to a delay in recognition, diagnosis and referral to appropriate services and treatment.
It is not uncommon for sufferers to present to general practice complaining of other (but related) problems such as lethargy, dizziness, gastrointestinal disturbances and poor sleep. They may also present with tooth decay and erosion if self-induced vomiting is recurrent. The physical effects of anorexia nervosa are potentially life-threatening and should not be underestimated. Symptoms often include significant fatigue and cold intolerance as well as symptoms secondary to hypotension, such as dizziness and syncope. Physical signs are often identified on examination and may include evidence of cachexia (including a reduction in muscle-mass and subcutaneous adipose), acrocyanosis (red-purple discolouration of the extremities), peripheral oedema, dry skin, hair loss or the development of lanugo hair (downy hair on the face and upper body), bradycardia and hypotension.5
Management
Depending on the age of onset, sufferers of anorexia nervosa may be in contact with a variety of services including education, social and health. Those in adolescence are at the greatest potential risk of adverse outcomes and so particular caution should be exercised if an eating disorder is suspected in a young person. For all ages, NICE recommends that if anorexia nervosa is suspected after initial assessment in primary care, referral to an appropriate community-based eating disorder service should be considered.6 Initial assessment should determine the nature and duration of symptoms, the severity of physical health sequelae, basic physical measurements (blood pressure, pulse, weight, height and BMI), and investigations where appropriate (ECG to monitor for bradycardia or QTc prolongation and blood tests to establish the level of malnutrition or electrolyte abnormalities). It is also crucial to assess the impact on day to day function and screen for comorbid mental disorders such as depression and anxiety, which are not uncommon. If physical health is severely compromised then inpatient admission to a specialist eating disorder unit should be organised. On occasion it may be valid and necessary to consider detention under the Mental Health Act to achieve this.7
Psychological treatment
This is the mainstay of treatment but may take a number of forms. Family therapy is often utilised in younger sufferers due to the importance of the role of parents and the family unit as a whole in the recovery process. In adults, up to 40 sessions of eating disorder-focussed CBT may be recommended. This utilises the same approaches as non-focussed CBT and aims to explore the links between thoughts, feelings and eating behaviours, enhancing self-confidence and setting homework to be completed outside the therapeutic environment. Maudsley Anorexia Nervosa Treatment for Adults (MANTRA) is also recommended by NICE and usually consists of over 20 sessions of focussed therapy based around the associated workbook.6 Specialist supportive clinical management (SSCM) is available in some areas and again therapy continues for over 20 weeks. Both MANTRA and SSCM revolve around the development of an effective therapeutic relationship to set goals and achieve change. A psychodynamic approach may be considered for those who have failed to respond to other therapy modalities.
Physical treatment
It is important at the start of treatment to set the key goal of achieving a healthy body weight and clearly defining what this is. Weight should be monitored on a regular basis and progress discussed. Weight gain should be slow and ideally not exceed 0.5kg per week. Dietetic input will be invaluable in determining how weight gain may be practically achieved using a variety of strategies. This may include increasing overall daily calorie intake via snacks or fortifying meals and drinks. NICE recommends that a multivitamin and mineral supplement should also be taken orally.
Fluid and electrolyte balance should be regularly assessed and include blood tests taken for U&Es, LFTs, magnesium, inorganic phosphate, glucose and FBC. The lower the starting BMI, the more frequently monitoring should be performed and initially this may need to be biweekly in the community setting. There is a risk of refeeding syndrome (seen as a rapid reduction in magnesium, phosphate or potassium levels) when oral intake is increased too rapidly, hence the need for monitoring. If malnutrition is severe, feeding via nasogastric tube in hospital may be necessary. If there are cardiovascular complications or a positive family history of significant cardiac disease, serial ECGs, at least on a monthly basis or more frequently if there are concerns, should be performed until an adequate and stable weight is achieved.
Pharmacological treatment
There is no licenced pharmacological treatment specifically for anorexia nervosa. Benzodiazepines are first-line if there is a significant level of agitation that cannot be managed successfully via other means. Comorbid mental disorders should be treated according to usual guidance, taking physical health and the potential for side effects into consideration. An SSRI would usually be recommended for anxiety or depression. Olanzapine and other antipsychotics are sometimes prescribed at a small dose either for their sedative or appetite-stimulating effects.
Dr Laura Stevenson is a higher trainee in psychiatry North Staffordshire Combined Health Care NHS Trust. Dr Ravindra Belgamwar is a consultant psychiatrist and honorary lecturer North Staffordshire Combined Health Care NHS Trust.
