|The ICD-10 Classification of Mental and Behavioural
World Health Organization, Geneva, 1992
F50.0 Anorexia Nervosa
Anorexia nervosa is a disorder characterized by deliberate
weight loss, induced and/or sustained by the patient. The disorder
occurs most commonly in adolescent girls and young women, but
adolescent boys and young men may be affected more rarely, as may
children approaching puberty and older women up to the menopause.
Anorexia nervosa constitutes an independent syndrome in the
(a) the clinical features of the syndrome are easily
recognized, so that diagnosis is reliable with a high level of
agreement between clinicians;
(b) follow-up studies have shown that, among patients who do not
recover, a considerable number continue to show the same main
features of anorexia nervosa, in a chronic form.
Although the fundamental causes of anorexia nervosa remain
elusive, there is growing evidence that interacting sociocultural
and biological factors contribute to its causation, as do less
specific psychological mechanism and a vulnerability of
personality. The disorder is associated with undernutrition of
varying severity, with resulting secondary endocrine and metabolic
changes and disturbances of bodily function. There remains some
doubt as to whether the characteristic endocrine disorder is
entirely due to the undernutrition and the direct effect of
various behaviours that have brought it about (e.g. restricted
dietary choice, excessive exercise and alterations in body
composition, induced vomiting and purgation and the consequent
electrolyte disturbances), or whether uncertain factors are also
For a definite diagnosis, all the following are required:
(a) Body weight is maintained at least 15% below that expected
(either lost or never achieved), or Quetelet's body-mass index is
17.5 or less. Prepubertal patients may show failure to make the
expected weight gain during the period of growth.
(b) The weight loss is self-induced by avoidance of
"fattening foods" and one or more of the following:
self-induced vomiting; self-induced purging; excessive exercise;
use of appetite suppressants and/or diuretics.
(c) There is body-image distortion in the form of a specific
psychopathology whereby a dread of fatness persists as an
intrusive, overvalued idea and the patient imposes a low weight
threshold on himself or herself.
(d) A widespread endocrine disorder involving the
hypothalamic-pituitary-gonadal axis is manifest in women as
amenorrhoea and in men as a loss of sexual interest and potency.
(An apparent exception is the persistence of vaginal bleeds in
anorexic women who are receiving replacement hormonal therapy,
most commonly taken as a contraceptive pill.) There may also be
elevated levels of growth hormone, raised levels of cortisol,
changes in the peripheral metabolism of the thyroid hormone, and
abnormalities of insulin secretion.
(e) If onset is prepubertal, the sequence of pubertal events is
delayed or even arrested (growth ceases; in girls the breasts do
not develop and there is a primary amenorrhoea; in boys the
genitals remain juvenile). With recovery, puberty is often
completed normally, but the menarche is late.
There may be associated depressive or obsessional symptoms, as
well as features of a personality disorder, which may make
differentiation difficult and/or require the use of more than one
diagnostic code. Somatic causes of weight loss in young patients
that must be distinguished include chronic debilitating diseases,
brain tumors, and intestinal disorders such as Crohn's disease or
a malabsorption syndrome.
ICD-10 copyright © 1992 by World
AZ Psychiatry copyright
by Dr. Manaan Kar Ray