Anorexia nervosa

Making a diagnosis

In order to establish a diagnosis of anorexia nervosa either the classification suggested by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) or by the World Health Organization's International Statistical Classification of Diseases and Related Health Problems(ICD) should be used.

There is no biochemical or haematological test for anorexia nervosa, however every case that is suspected should have a Diagnostic work up, to exclude other causes of weight loss and to check for biological parameters that may be affected by the illness itself. The diagnosis relies on a combination of exploring the beliefs of the patient, the experience of the patient and others and the physical characteristics exhibited by the patient.  Notably, diagnostic criteria are intended to assist clinicians, and are not intended to be representative of what an individual sufferer feels or experiences in living with the illness.

The diagnostic criteria used in the DSM-IV-TR are:-

  • A refusal to maintain body weight at or above a minimally normal weight for age and height: weight loss leading to maintenance of body weight <85% of that expected, or failure to make expected weight gain during period of growth.
  • An intense fear of gaining weight or becoming fat, even though underweight.
  • A disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
  • The absence of at least three consecutive menstrual cycles (amenorrhea) in women who have had their first menstrual period but have not yet gone through menopause(postmenarce, premenopausal females)

Furthermore, the DSM-IV-TR specifies two subtypes:

  • Restricting Type: during the current episode of anorexia nervosa, the person has not regularly engaged in binge-eating or purging behaviour (that is, self-induced vomiting, or the misuse of laxatives, diuretics, or enemas). Weight loss is accomplished primarily through dieting, fasting, or excessive exercise.
  • Binge-Eating Type or Purging Type: during the current episode of anorexia nervosa, the person has regularly engaged in binge-eating OR purging behaviour (that is, self-induced vomiting, or the misuse of laxatives, diuretics, or enemas).

ICD-10 criteria are similar, but in addition, specifically mention:

  • The ways that individuals might induce weight-loss or maintain low body weight (avoiding fattening foods, self-induced vomiting, self-induced purging, excessive exercise, excessive use of appetite suppressants or diuretics).
  • Certain physiological features, including "widespread endocrine disorder involving hypothalamic-pituitary-gonadal axis is manifest in women as amenorrhoea and in men as loss of sexual interest and potency. There may also be elevated levels of growth hormones, raised cortisol levels, changes in the peripheral metabolism of thyroid hormone and abnormalities of insulin secretion".
  • If onset is before puberty, that development is delayed or arrested.

How does anorexia nervosa present?

Anorexia nervosa particularly in its early stage may be difficult to spot both for healthcare professionals and for close members of the family. Once established the physical, psychological and social effects of the condition may lead to a number of conditions:

Physical conditions that may be associated with anorexia nervosa Psychological symptoms that may be associated with anorexia nervosa Social behaviours that may be associated with anorexia nervosa
Significant weight loss Obsessional thoughts/actions regarding food and weight Excessive exercise
Postural hypotension Distorted body image thinking they are fat even when they are under weight Being secretive about behaviours e.g. eating or exercise
Body mass index below 17.5 in adults Low self-esteem Social withdrawal
Anaemia Phobic thoughts about weight gain Deliberate self harm
Less than 85% of expected weight in children/adolescents Poor insight into condition Substance abuse
Reduced white cell count Depressed mood, clinical depression, mood swings and anxiety Short tempered and argumentative or even aggressive around the subject of food
Amenorrhoea Difficulty interacting with others either being short tempered or socially withdrawn Frequently checking body shape in a mirror or weight on a scales
Reduced function of the immune system Obsessive-compulsive disorder  
Slow heart rate, reduced metabolic rates which may lead to hypotension Refusal to accept the concept of a normal weight even in the context of a dangerously low weight  
Stunted growth Feeling that control over their weight gives them control over their life  
Electrolyte disturbance Evaluating themselves mainly in terms of their body shape and weight  
Dental caries    
Mineral deficiency notably zinc    
Poorly developed secondary sexual characteristics    
Weak or brittle fingernails    
Thinning of the hair    
Decreased sexual drive in males    



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