Diagnostic Features
The essential features of Anorexia Nervosa are that the individual refuses to maintain a minimally normal body weight, is intensely afraid of gaining weight, and exhibits a significant disturbance in the perception of the shape or size of his or her body. In addition, postmenarcheal females with this disorder are amenorrheic. (The term anorexia is a misnomer because loss of appetite is rare.)
The individual maintains a body weight that is below minimally normal level for age and height (Criterion A). When Anorexia Nervosa develops in an individual during childhood or early adolescence, there may be failure to make expected weight gains (i.e., while growing in height) instead of weight loss.
Criterion A provides a guideline for determining when the individual meets the threshold for being underweight. It suggests that the individual weigh less than 85% of that weight that is considered normal for that person's age and height (usually computed using one of the Metropolitan Life Insurance tables or pediatric growth charts). An alternative and somewhat stricter guideline (used in the ICD-10 Diagnostic Criteria for Research) requires that the individual have a body mass index (BMI) (calculated as weight in kilograms/height in meters squared) equal to or below 17.5kg/m^2. These cutoffs are provided only as suggested guidelines for the clinician, since it is unreasonable to specify a single standard for minimally normal weight that applies to all individuals of a given age and height. In determining a minimally normal weight, the clinician should consider not only such guidelines but also the individual's body build and weight history.
Usually weight loss is accomplished primarily through reduction in total food intake. Although individuals may begin by excluding from their diet what they perceive to be highly caloric foods, most eventually end up with a very restricted diet that is sometimes limited to only a few foods. Additional methods of weight loss include purging (i.e., self-induced vomiting or the misuse of laxatives or diuretics) and increased or excessive exercise.
Individuals with this disorder intensely fear gaining weight or becoming fat (Criterion B). This intense fear of becoming fat is usually not alleviated by the weight loss. In fact, concern about weight gain often increases even as actual weight continues to decrease.
Familial Pattern
There is an increased risk of Anorexia Nervosa among first-degree biological relatives of individuals with the disorder. An increased risk of Mood Disorders has also been found among first-degree biological relatives of individuals with Anorexia Nervosa, particularly relatives of individuals with Binge-Eating/Purging Type. Studies of Anorexia Nervosa in twins have found concordance rates for monozygotic twins to be significantly higher than those for dizygotic twins.
Differential Diagnosis
Other possible causes of significant weight loss should be considered in the differential diagnosis of Anorexia Nervosa, especially when the presenting features are atypical (such as an onset of illness after age 40 years)
. In general medical conditions (e.g., gastrointestinal disease, brain tumors, occult malignancies, and acquired immunodeficiency syndrome [AIDs]), serious weight loss may occur, but individuals with such disorders usually do not have a distorted body image and a desire for further weight loss. The superior mesenteric artery syndrome (characterized by postprandial vomiting secondary to intermittent gastric outlet obstruction) should be distinguished from Anorexia Nervosa, although this syndrome may sometimes develop in individuals with Anorexia Nervosa because of their emaciation. In Major Depressive Disorder, severe weight loss may occur, but most individuals with Major Depressive Disorder do not have a desire for excessive weight loss or excessive fear of gaining weight. In Schizophrenia, individuals may exhibit odd eating behavior and occasionally experience significant weight loss, but they rarely show the fear of gaining weight and the body image disturbance required for a diagnosis of Anorexia Nervosa.
The essential features of Anorexia Nervosa are that the individual refuses to maintain a minimally normal body weight, is intensely afraid of gaining weight, and exhibits a significant disturbance in the perception of the shape or size of his or her body. In addition, postmenarcheal females with this disorder are amenorrheic. (The term anorexia is a misnomer because loss of appetite is rare.)
The individual maintains a body weight that is below minimally normal level for age and height (Criterion A). When Anorexia Nervosa develops in an individual during childhood or early adolescence, there may be failure to make expected weight gains (i.e., while growing in height) instead of weight loss.
Criterion A provides a guideline for determining when the individual meets the threshold for being underweight. It suggests that the individual weigh less than 85% of that weight that is considered normal for that person's age and height (usually computed using one of the Metropolitan Life Insurance tables or pediatric growth charts). An alternative and somewhat stricter guideline (used in the ICD-10 Diagnostic Criteria for Research) requires that the individual have a body mass index (BMI) (calculated as weight in kilograms/height in meters squared) equal to or below 17.5kg/m^2. These cutoffs are provided only as suggested guidelines for the clinician, since it is unreasonable to specify a single standard for minimally normal weight that applies to all individuals of a given age and height. In determining a minimally normal weight, the clinician should consider not only such guidelines but also the individual's body build and weight history.
Usually weight loss is accomplished primarily through reduction in total food intake. Although individuals may begin by excluding from their diet what they perceive to be highly caloric foods, most eventually end up with a very restricted diet that is sometimes limited to only a few foods. Additional methods of weight loss include purging (i.e., self-induced vomiting or the misuse of laxatives or diuretics) and increased or excessive exercise.
Individuals with this disorder intensely fear gaining weight or becoming fat (Criterion B). This intense fear of becoming fat is usually not alleviated by the weight loss. In fact, concern about weight gain often increases even as actual weight continues to decrease.
Familial Pattern
There is an increased risk of Anorexia Nervosa among first-degree biological relatives of individuals with the disorder. An increased risk of Mood Disorders has also been found among first-degree biological relatives of individuals with Anorexia Nervosa, particularly relatives of individuals with Binge-Eating/Purging Type. Studies of Anorexia Nervosa in twins have found concordance rates for monozygotic twins to be significantly higher than those for dizygotic twins.
Differential Diagnosis
Other possible causes of significant weight loss should be considered in the differential diagnosis of Anorexia Nervosa, especially when the presenting features are atypical (such as an onset of illness after age 40 years)
. In general medical conditions (e.g., gastrointestinal disease, brain tumors, occult malignancies, and acquired immunodeficiency syndrome [AIDs]), serious weight loss may occur, but individuals with such disorders usually do not have a distorted body image and a desire for further weight loss. The superior mesenteric artery syndrome (characterized by postprandial vomiting secondary to intermittent gastric outlet obstruction) should be distinguished from Anorexia Nervosa, although this syndrome may sometimes develop in individuals with Anorexia Nervosa because of their emaciation. In Major Depressive Disorder, severe weight loss may occur, but most individuals with Major Depressive Disorder do not have a desire for excessive weight loss or excessive fear of gaining weight. In Schizophrenia, individuals may exhibit odd eating behavior and occasionally experience significant weight loss, but they rarely show the fear of gaining weight and the body image disturbance required for a diagnosis of Anorexia Nervosa.
Diagnostic criteria for 307.1 Anorexia Nervosa
A. Refusal to maintain body weight at or above a minimally normal weight for age and height (e.g., weight loss leading to maintenance of body weight less than 85% of that expected; or failure to make expected weight gain during period of growth, leading to body weight less than 85% of that expected).
B. Intense fear of gaining weight or becoming fat, even though underweight.
C. Disturbance in the way in which one's body weight or shape is experience, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
D.In postmenarcheal females, amenorrhea, i.e., the absence of at least three consecutive menstrual cycles. (A woman is considered to have amenorrhea if her periods occur only following hormone, e.g., estrogen, administration.)
Specify Type:
Restricting Type: during the current episode of Anorexia Nervosa, the person has not regularly engaged in binge-eating or purging behavior (i.t., self-induced vomiting or the misuse of laxatives, diuretics or enemas).
Binge-eating/Purging Type: during the current episode of Anorexia Nervosa, the person has regularly engaged in binge-eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas).
American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.
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