Etiology and Pathogenesis

In the United States, it is estimated that the lifetime prevalence of anorexia nervosa is 0.5% and 1% to 3% for bulimia nervosa. Ten percent of all eating disorder patients are males. The current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) outlines the criteria for the diagnosis of anorexia nervous and bulimia nervosa as summarized in Box 85-1. Although a main feature of the diagnosis of anorexia nervosa is a body weight that is below 85% of that expected for age and height, for younger patients, the diagnosis can be made without weight loss from previous visits if the patient fails to make the expected weight gains of normal growth. The DSM-IV criteria for bulimia nervosa require recurrent episodes of regular binge eating with inappropriate compensatory behaviors to avoid weight gain. Eating disorder not otherwise specified encompasses eating disorders that do not meet full DSM-IV criteria for either anorexia or bulimia nervosa. Some reports show that more than 50% of adolescents with eating disorders fall into this category; these patients still require appropriate treatment because they have the same underlying eating behaviors and can develop the same life-threatening complications.

Clinical Presentation

Pediatricians may be alerted to the early stages of an eating disorder during their evaluations at the patient’s routine and acute visits. Weight loss or failure to gain weight may be an initial finding. Vital signs may also reveal bradycardia, a lower blood pressure, or hypothermia compared with previous visits. A patient with anorexia nervosa may present with thinning of scalp hair, lanugo or fine hair growth on the extremities, dry skin, acrocyanosis, and bruising or calluses related to overexercising. Bulimia nervosa may be considered if the pediatrician notes scarring or abrasions in the back of the mouth, parotid gland hypertrophy, dental enamel erosions, or calluses on the dorsum of the fingers known as Russell’s sign, which result from self-induced vomiting. Some of the symptoms of patients with bulimia nervosa are summarized in Figure 85-1.

Figure 85-1 Signs and symptoms of bulimia nervosa.

If a pediatrician becomes concerned that a patient may be at risk for an eating disorder, screening for known risk factors may be helpful. Although patients and even their parents or guardians may not be fully able to report the degree of restriction or purging during the early stages of weight loss, reports of changing eating patterns, such as giving up favorite foods or eating away from family members, may be useful information. In addition to changing eating patterns, pediatricians should screen for known risk factors, including history of dieting, childhood or family concerns regarding weight gain, participation in competitive sports that focus on maintaining a specific weight such as gymnastics or wrestling, or participation in sports that can result in lower body fat stores such as cross-country running or swimming. Social history will shed light on other psychiatric diagnosis that could increase the risk of an eating disorder, including obsessive-compulsive symptoms associated with anorexia nervosa and substance use or alcohol misuse associated with bulimia. Difficulties in family communication, ability to manage conflict, or marital tension may also be risk factors.

The family history may be notable for a first-degree relative with an eating disorder as studies have found that adolescents whose first-degree relatives have eating disorders are 6 to 10 times more likely to develop an eating disorder.

Differential Diagnosis

The differential diagnosis of eating disorders includes other medical and psychiatric conditions that can account for the symptoms of weight loss or, in the case of bulimia, chronic vomiting or electrolyte abnormalities (Box 85-2). These diagnoses need to be excluded by history or laboratory evaluation because the resulting malnutrition associated with these chronic conditions can look very much like an eating disorder.

Laboratory evaluation will also help to assess the degree to which an adolescent is affected by the disorder. Laboratory evaluation includes a complete blood count, erythrocyte sedimentation rate, electrolytes, calcium, magnesium, phosphorus, serum glucose, blood urea nitrogen, creatinine, and urinalysis. If the patient has amenorrhea, pregnancy should be ruled out; in addition, thyroid function tests, serum prolactin, follicle-stimulating hormone level, luteinizing hormone level, and estradiol can be obtained. A morning screening serum cortisol and adrenocorticotrophic hormone level will help to exclude Addison’s disease, which has been reported to present similarly to anorexia nervosa. An electrocardiogram (ECG) should be obtained to assess any changes that may result from electrolyte shifts and to document the degree of bradycardia. Patients with long-standing amenorrhea may benefit from a bone densitometry study.

Management

Adolescents with eating disorders are best cared for by an interdisciplinary treatment team, including a pediatrician or medical clinician, a nutritionist, and a mental health provider. Having a system of communication that allows for the three providers to update one another regarding progress and concerns will greatly improve coordination of the team’s care plan.

The pediatrician should monitor weight gain; vital sign stability, including bradycardia; electrolyte abnormalities that may result from dehydration, refeeding, or purging; and long-term concerns, including amenorrhea and osteopenia. The pediatrician should schedule weekly visits to assess vital signs and weight gain. Expected rates of weight gain depend on the patient’s percent ideal body weight. Outpatient treatment for an adolescent who is medically stable typically aims to increase weight at 1 to 2 lb per week. During the period of initial weight gain, the medical provider may prescribe multivitamins and additional calcium. Clinicians vary in their comfort in providing short-term promotility agents and osmotic laxatives to enhance gut motility and minimize the symptoms of constipation.

The nutritionist will educate patients regarding balanced nutrition, assist patients in making specific dietary choices, and help patients to gain weight following a controlled plan.

Ensuring that the patient receives care from a mental health provider with experience in treating eating disorders in adolescent patients is essential for long-term healing. Effective treatment strategies include cognitive behavioral approaches, interpersonal psychotherapies, and family-based therapies, including the Maudsley method.

Pharmacotherapy for anorexia nervosa has not demonstrated significant efficacy, but comorbid disorders such as obsessive-compulsive disorder may benefit from treatment. Antidepressants such as selective serotonin reuptake inhibitors can reduce binge-eating and purging behaviors and reduce relapse rates in bulimia nervosa.

Inpatient hospitalization or psychiatric residential treatment may be required for severely affected adolescents who are dehydrated, have significant bradycardia, demonstrate risk for arrhythmia on ECG (i.e., a prolonged QTc), have electrolyte abnormalities, are poorly motivated for recovery, or express suicidality. A major complication of the treatment of anorexia nervosa or any patient who is severely malnourished is refeeding syndrome. This occurs when rapidly refeeding leads to hypophosphatemia, which can affect multiple organ systems, producing cardiac, neurologic, neuromuscular, pulmonary, and hematologic complications, and may present as confusion, coma, convulsions and death. Thus, refeeding must be performed carefully with close monitoring and potential supplementation of phosphate, as well as other electrolytes.

Prognosis

Almost half of patients with anorexia nervosa recover without long-term sequelae. An estimated 25% of patients improve but remain symptomatic, and approximately another 25% of patients may have chronic symptoms of anorexia nervosa. Long-term mortality may be as high as 10% and usually results from malnutrition, suicide, or other physiologic complications. The majority of adolescents with bulimia recover with effective treatment. Patients with a history of high frequency of pretreatment vomiting, longer duration of symptoms before initiation of treatment, and substance abuse are at increased risk for developing relapsing bulimic behaviors.

Conclusion

In the past decade, pediatricians have been challenged to balance messages related to the risks of obesity with prevention messages related to the risks of unhealthy dieting to achieve thinness. Having regular visits with children and adolescents allows pediatricians to observe weight trends and health behavior patterns over the course of the patient’s development. Being attuned to the adolescent’s concerns related to his or her body, screening for risk factors associated with an eating disorder, and addressing potential eating disorders early will help to minimize the long-term risks associated with an eating disorder. Developing an interdisciplinary team to address patients who have eating disorders is essential in ensuring recovery. Advocating for access to effective care if the patient requires hospitalization or long-term care may be time consuming for the pediatrician but is extremely important. With the support of informed and effective pediatricians, adolescents at risk for an eating disorder will have a much better chance of avoiding significant risks and developing safe and healthy eating and exercise patterns for life.