Anorexia Nervosa

Essentials of Diagnosis

• Restriction of calorie intake, leading to underweight BMI (BMI < 18.5)

• Intense fear of gaining weight or behavior that prevents weight gain despite underweight BMI

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

• Denial of the medical seriousness of underweight status

General Considerations

• Characterized by underweight BMI, intense fear of gaining weight and distorted perception of body image

• Begins in the years between adolescence and young adulthood

• Cause not known, probably of primary psychiatric origin

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

• The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) classifies the severity of anorexia according to BMI:

  • Mild: BMI 17–18.49

  • Moderate: BMI 16–16.99

  • Severe: BMI 15–15.99

  • Extreme: BMI < 15

• DSM–5 defines two subtypes of anorexia nervosa

  • Binge-eating/purging type is characterized by recurrent episodes of binge-eating or purging (ie, self-induced vomiting and/or abuse of diuretics, laxatives, enemas, cathartics)

  • Restricting type is characterized by dieting, fasting or excessive exercising without associated binge-eating or purging

Demographics

• 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

Symptoms and Signs

• Loss of body fat with severe emaciation

• Dry and scaly skin

• Increased lanugo body hair

• Parotid enlargement and edema

• In severe cases, bradycardia, hypotension, and hypothermia

• Cold intolerance

• Constipation

• Amenorrhea

Differential Diagnosis

• Bulimia nervosa, binge eating disorder

• 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

Laboratory Tests

• 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 gonadotropin-releasing hormone

Medications

• 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 difficulties

• Therapeutic modalities

  • Supportive care

  • Structured behavioral therapy

  • Intensive psychotherapy

  • Family therapy

  • Hospitalization may be necessary

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

Complications

• Poor dentition

• Pharyngitis

• Esophagitis

• Aspiration

• Gastric dilatation

• Pancreatitis

• Constipation

• Hemorrhoids

• Dehydration

• Electrolyte abnormalities

Prognosis

• 50% of patients continue to experience difficulties with eating behavior and psychiatric problems

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

When to Refer

• Adolescents and young adults with otherwise unexplained weight loss should be evaluated by a psychiatrist

• All patients with diagnosed anorexia nervosa should be co-managed with a psychiatrist

When to Admit

• Signs of hypovolemia, major electrolyte disorders, and severe protein-energy malnutrition

• Failure to improve with outpatient management