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Am Fam Physician. 2002;65(3):476-478

Patients with anorexia nervosa, characterized by abnormal eating habits that cause weight loss, can present with symptoms that range from mild and nonspecific weakness to substantial weight loss and lack of energy. They are frequently unconcerned about their weight loss, and family members often bring them to the physician because of observed weight loss or amenorrhea. The criteria for diagnosing anorexia nervosa are defined in Table 1. Two subtypes include “restricting,” in which food intake is voluntarily limited, and “purging,” in which patients engage in purging behaviors. Mehler reviews the diagnosis and care of these patients.

The most common presentation is an adolescent or young woman with profound cachexia. Other anorexia-associated characteristics include higher socioeconomic class, participation in modeling and athletics, and type 1 diabetes. Proposed psychologic risk factors include perfectionism and overprotective parenting. Although both bulimic and anorectic patients have abnormal eating habits and often exercise excessively, bulimia can be determined by the habit of binge eating and purging (Table 2). Symptoms and signs of purging habits include reflux esophagitis, abdominal cramping, diarrhea, and rectal bleeding. Electrolyte abnormalities and metabolic alkalosis signal extreme purging habits in a bulimic patient. Patients with anorexia generally have laboratory test results within normal limits until the very late stage of the condition.

Intense fear of weight gain
Undue emphasis on body shape
Body weight less than 85 percent of predicted
Amenorrhea for three consecutive months

The initial course of treatment for patients with anorexia nervosa involves determining the level of treatment: outpatient, acute inpatient, or acute psychiatric. Patients with mild cases who are within 10 percent of ideal body weight and have a relatively normal body image actually have a not-otherwise-specified eating disorder rather than anorexia nervosa. These patients, and those with weight 25 to 30 percent below ideal body weight who are relatively asymptomatic and functional, can be treated as outpatients. Inpatient care becomes more appropriate in patients with greater weight loss, marked symptoms of hypotension or dizziness, or arrhythmias. Involvement of an experienced mental health professional is useful in helping patients alter the thought processes that result in abnormal behaviors. The primary care physician should monitor physical status and weight, and discourage athletic activity until relative normalization of weight is achieved.

Recurrent episodes of binge eating characterized by either a larger amount of food than most people would eat in a discrete period or a sense people would eat in a discrete period or a sense of having no control over eating during the episode
Recurrent, inappropriate, compulsive behavior to prevent weight gain, such as self-induced vomiting; abuse of laxatives, diuretics, or other medications; or excessive exercise
Bingeing and purging at least twice per week for three months
Self-evaluation unduly influenced by body shape and weight

Caloric need is calculated by identifying the target weight and adjusting the diet to gain lb (0.45 kg) per week in outpatients and to 3 lb (0.9 to 1.35 kg) per week in inpatients. After starting a low-calorie diet of 800 to1,000 kcal per day, gradual increments of 200 to 300 kcal every three to four days as tolerated are indicated until 3,000 to 3,500 kcal per day is reached. Refeeding syndrome, in which cardiovascular collapse occurs after early high caloric intake, results in phosphate depletion and is a potential complication that can be avoided by monitoring serum electrolyte levels during the early phase of treatment. Cardiac monitoring is appropriate when the heart rate falls below 40 beats per minute, but some bradycardia and hypotension are normal, energy-saving mechanisms and simply require observation. A prolonged QT interval is a marker for sudden-death risk.

Metoclopramide may relieve bloating caused by increased dietary intake. Secondary amenorrhea results from low levels of follicle-stimulating hormone and luteinizing hormone in the presence of low estrogen levels. Therapy requires nutritional improvement and weight gain. Withdrawal bleeding cannot be stimulated because of low estrogen. Menstruation will usually resume when the patient approaches 90 percent of ideal body weight. Patients can become pregnant despite amenorrhea. Osteopenia, resulting in osteoporosis, is caused by low turnover with increased bone resorption and cannot be reversed with estrogen. Calcium and vitamin D supplementation are appropriate. The utility of bisphosphonates and calcitonin is uncertain, and these agents should be reserved for use in the patient with ongoing, deteriorating bone density.

The author concludes that anorexia nervosa is a common and serious condition requiring a multidisciplinary approach to treatment. The treatment goal is to prevent continued weight loss and physical deterioration. Long-term therapy may include cognitive behavioral psychotherapy, family counseling, and judicious use of psychopharmacology.

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