ESSENTIALS OF DIAGNOSIS
Disturbance of body image and intense fear of becoming fat.
Weight loss leading to body weight 15% below expected.
In females, absence of three consecutive menstrual cycles.
Anorexia nervosa typically begins in the years between adolescence and young adulthood. Ninety percent of patients are female, most of middle and upper socioeconomic status.
The prevalence of anorexia nervosa is greater than previously suggested. In Rochester, Minnesota, for example, the prevalence per 100,000 population is estimated to be 270 for females and 22 for males. Many adolescent girls have features of the disorder without the severe weight loss.
The cause of anorexia nervosa is not known. Although multiple endocrinologic abnormalities exist in these patients, most authorities believe they are secondary to malnutrition and not primary disorders. Most experts favor a primary psychiatric origin, but no hypothesis explains all cases. Comorbidity with depression or anxiety is not uncommon and can be particularly pernicious. The patient characteristically comes from a family whose members are highly goal-oriented. The parents may be directive and concerned with slimness and physical fitness, and family conversation often centers around dietary matters. One theory holds that the patient’s refusal to eat is an attempt to regain control of one’s body in defiance of parental control. The patient’s unwillingness to inhabit an “adult body” may also represent a rejection of adult responsibilities and the implications of adult interpersonal relationships. Patients are often perfectionistic in behavior and exhibit obsessional personality characteristics.
Patients with anorexia nervosa may exhibit severe emaciation and may complain of cold intolerance or constipation. Amenorrhea is almost always present. Bradycardia, hypotension, and hypothermia may be present in severe cases. Examination demonstrates loss of body fat, dry and scaly skin, and increased lanugo body hair. Parotid enlargement and edema may also occur.
Laboratory findings are variable but may include anemia, leukopenia, electrolyte abnormalities, and elevations of blood urea nitrogen (BUN) and serum creatinine. Serum cholesterol levels are often increased. Endocrine abnormalities include depressed levels of luteinizing and follicle-stimulating hormones and impaired response of luteinizing hormone to luteinizing hormone-releasing hormone.
DIAGNOSIS & DIFFERENTIAL DIAGNOSIS
The diagnosis is based on weight loss to a body weight 15% below expected, distorted body image, fear of weight gain or of loss of control over food intake and, in females, absence of at least three consecutive menstrual cycles. Other medical or psychiatric illnesses that can account for anorexia and weight loss must be excluded.
Behavioral features required for the diagnosis include intense fear of developing obesity, disturbance of body image, and refusal to exceed a minimal normal weight.
The differential diagnosis includes endocrine and metabolic disorders (eg, panhypopituitarism, Addison disease, hyperthyroidism, and diabetes mellitus); ...