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For further information, see CMDT Part 29-05: Anorexia Nervosa
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Essentials of Diagnosis
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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
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General Considerations
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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
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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
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Differential Diagnosis
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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
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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
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Therapeutic Procedures
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Poor dentition
Pharyngitis
Esophagitis
Aspiration
Gastric dilatation
Pancreatitis
Constipation
...