55 EATING DISORDERS
Harrison’s Manual of Medicine
Anorexia nervosa is characterized by refusal to maintain normal body weight, resulting in a body weight < 85% of the expected weight for age and height. Bulimia nervosa is characterized by recurrent episodes of binge eating followed by abnormal compensatory behaviors, such as self-induced vomiting, laxative abuse, or excessive exercise. Weight is in the normal range or above.
Both anorexia nervosa and bulimia nervosa occur primarily among previously healthy young women who become overly concerned with body shape and weight. Binge eating and purging behavior may be present in both conditions, with the critical distinction between the two resting on the weight of the individual. The diagnostic criteria for each of these disorders are shown in Table 55-1 and Table 55-2.
Table 55-1 Diagnostic Criteria for Anorexia Nervosa
Table 55-2 Diagnostic Criteria for Bulimia Nervosa
Skin, hair, nails: alopecia, lanugo, acrocyanosis, edema
Cardiovascular: bradycardia, hypotension
Gastrointestinal: salivary gland enlargement, slow gastric emptying, constipation, elevated liver enzymes
Hematopoietic: normochromic, normocytic anemia; leukopenia
Fluid/electrolyte: increased BUN, increased creatinine, hyponatremia, hypokalemia
Endocrine: low luteinizing hormone and follicle-stimulating hormone with secondary amenorrhea, hypoglycemia, normal thyroid-stimulating hormone with low normal thyroxine, increased plasma cortisol, osteopenia
Gastrointestinal: salivary gland enlargement, dental erosion
Fluid/electrolyte: hypokalemia, hypochloremia, alkalosis (from vomiting) or acidosis (from laxative abuse)
Other: loss of dental enamel, callus on dorsum of hand
Anorexia Nervosa Weight restoration to 90% of predicted weight is the primary goal in the treatment of anorexia nervosa. The intensity of the initial treatment, including the need for hospitalization, is determined by the pt’s current weight, the rapidity of recent weight loss, and the severity of medical and psychological complications (Fig. 55-1). Severe electrolyte imbalances should be identified and corrected. Nutritional restoration can almost always be successfully accomplished by oral feeding. For severely underweight pts, sufficient calories should be provided initially in divided meals as food or liquid supplements to maintain weight and to permit stabilization of fluid and electrolyte balance (1500–1800 kcal/d intake). Calories can be gradually increased to achieve a weight gain of 1 to 2 kg per week (3000–4000 kcal/d intake). Meals must be supervised. Intake of vitamin D (400 IU/d) and calcium (1500 mg/d) should be sufficient to minimize bone loss. The assistance of psychiatrists or psychologists experienced in the treatment of anorexia nervosa is usually necessary. No psychotropic medications are of established value in the treatment of anorexia nervosa. Medical complications occasionally occur during refeeding; most patients transiently retain excess fluid, occasionally resulting in peripheral edema. Congestive heart failure and acute gastric dilatation have been described when refeeding is rapid. Transient modest elevations in serum levels of liver enzymes occasionally occur. Low levels of magnesium and phosphate should be replaced. Mortality is 5% per decade, either from chronic starvation or suicide.
Bulimia Nervosa Bulimia nervosa can usually be treated on an outpatient basis (Fig. 55-1). Cognitive behavioral therapy and fluoxetine (Prozac) are first-line therapies. The recommended treatment dose for fluoxetine (60 mg/d) is higher than that typically used to treat depression.
For a more detailed discussion, see Walsh TB: Eating Disorders, Chap. 78, p. 486, in HPIM-15.