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Anorexia Nervosa: Clinical Features
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Although anorexia nervosa probably has more media attention it is much less common than bulimia nervosa, prevalence rates being found to be around 0.5 per 100,000. The incidence, however, in young females particularly those who are ambitious and 'perfectionistic' may be as high as 1 in 250. Anorexia nervosa has a high mortality and morbidity rate, mortality being estimated between 5 and 20%. Recovery is often slow, 50% of patients recovering at 6 years and 70% at 33 years, other patients will following a relapsing remitting course and a significant proportion will die from the disorder.
Characteristic clinical features of anorexia nervosa include:
- Maintenance of a low body weight less than a body mass index of 17.5.
- Amenorrhoea either primary or secondary in females, in males loss of libido.
- A severe fear of fatness and phobia of normal body weight.
- A distorted body image where the individual does not recognise the degree of their emaciation. In particular as weight is gained they misinterpret changes in body weight and shape.
There are many aetiological factors involved in anorexia nervosa these include genetic, social and environmental. There does seem to be a clustering of anorexia nervosa within families in particular identical twins. Other factors in the family that are thought to promote the development of anorexia nervosa include parental discord and a history of childhood sexual abuse.
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Anorexia Nervosa: Medical Complications
On examination of an anorexic their skin, typically, is dry with a covering of soft, downy hair (lanugo). Secondary sexual characteristics are maintained. Examination may also reveal hypothermia, hypotension, bradycardia and/or oedema. The oestrogen deficiency that can occur may result in osteoporosis, and secondary fractures, type II hyperlipoproteinaemia and hypercholesterolaemia.
Starvation and purging in particular may result in hypokalaemia and hypochloraemic alkalosis. As a consequence the severely ill anorexic is prone to arrhythmia's an possible cardiac arrest.
A full blood count may show a microcytic anaemia with a low white count (note that as there may be B12 as well as iron deficiency the anaemia may be normocytic). Endocrine investigations show
- Elevated basal cortisol and loss of diurnal variation.
- Gonadotrophins and gonadal steroids are reduced.
- Thyrotrophin-releasing hormone test is impaired and T3 is low.
- Elevated growth hormone.
The last abnormality is due to carbohydrate restriction, the former three to low body weight.
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Anorexia Nervosa: Treatment
Treatment of anorexia nervosa has to combine both re-feeding and psychological therapies. At very low body weights the capacity of the patient to use psychological treatments is often poor with concrete thinking and sometimes confusional states being evident. In patients developing anorexia under the age of 18 family therapy is found to be effective although its use in older age groups is less clear. In less severely effected patients out-patient or day-patient treatment is of benefit but in those whose body mass index is less than 13 in-patient treatment is frequently required. Most in-patient treatments have a multidisciplinary approach with assessments being carried out by nurses, psychiatrists, psychologists, occupational therapists and dieticians. The treatment combines individual work and group therapy some patients responding to a cognitive behavioural approach, others to a more long term psychodynamic approach.
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