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For further information, see CMDT Part 29-05: Anorexia Nervosa

Key Features

Essentials of Diagnosis

  • Restriction of calorie intake leading to underweight BMI (BMI < 18.5 kg/m2)

  • Intense fear of gaining weight or behavior that prevents weight gain

  • Distorted perception of body image, with undue influence of weight on self-worth

  • Denial of the medical seriousness of underweight status

General Considerations

  • Begins in the years between adolescence and young adulthood

  • Two subtypes: binge-eating/purging type and restricting type

  • Cause not known, probably of primary psychiatric origin; comorbidity with depression, anxiety, or obsessive-compulsive disorder is not uncommon

  • Must exclude medical or psychiatric illnesses that can account for anorexia, weight loss

  • Severity is classified according to BMI

    • Mild, BMI 17–18.49 kg/m2

    • Moderate, BMI 16–16.99 kg/m2

    • Severe, BMI 15–15.99 kg/m2

    • Extreme, BMI < 15 kg/m2


  • Occurs most commonly in females (90%), predominantly middle and upper income

  • Estimated prevalence

    • 270 cases per 100,000 population for females

    • 22 cases per 100,000 population for males

Clinical Findings

Symptoms and Signs

  • Loss of body fat with severe emaciation

  • Dry and scaly skin

  • Increased lanugo body hair

  • Parotid enlargement and edema

  • In females of reproductive age, cessation of menstruation is common

  • In severe cases, bradycardia, hypotension, and hypothermia

  • Cold intolerance

  • Constipation

  • Amenorrhea

Differential Diagnosis

  • Endocrine and metabolic disorders

    • Panhypopituitarism

    • Addison disease

    • Hyperthyroidism

    • Diabetes mellitus

  • Gastrointestinal disorders

    • Malabsorption

    • Pancreatic insufficiency

    • Crohn disease

    • Gluten enteropathy

  • Chronic infections (eg, tuberculosis)

  • Cancer (eg, lymphoma)

  • Rare CNS disorders (eg, hypothalamic tumor)

  • Severe malnutrition

  • Depression

  • Obsessive-compulsive disorder

  • Body dysmorphic disorder

  • Malignancy

  • AIDS

  • Substance abuse


  • Check for anemia, leukopenia, electrolyte abnormalities, and elevations of blood urea nitrogen and serum creatinine

  • Serum cholesterol level often increased

  • Luteinizing hormone level depressed and impaired response to luteinizing hormone-releasing hormone



  • Tricyclic antidepressants, selective serotonin reuptake inhibitors, and lithium carbonate are effective in some cases

Therapeutic Procedures

  • Treatment goal: restoration of normal body weight and improvement in psychological comorbidities

  • Supportive care

  • Structured behavioral therapy

  • Intensive psychotherapy

  • Family therapy

  • Hospitalization may be necessary

  • Treatment by experienced teams successful in about two-thirds of cases



  • Poor dentition

  • Pharyngitis

  • Esophagitis

  • Aspiration

  • Gastric dilatation

  • Pancreatitis

  • Constipation

  • Hemorrhoids

  • Dehydration

  • Electrolyte abnormalities


  • 50% of patients continue to experience difficulties with underweight, eating behaviors, and psychiatric problems

  • 2–6% of patients die of the complications of the disorder or from suicide

When to Refer

  • Adolescents and young adults ...

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