This is a 16 year old female who is brought to your clinic for her annual well teen exam. She denies any physical complaints, except for an occasional cold. Specifically, she denies any history of fatigue, fever, appetite or weight change. She is active and a review of symptoms is completely negative. A psychosocial (HEADSS) screening interview reveals no significant disagreements with her parents. She is a nearly straight "A" student at a public secondary school. She smokes an occasional cigarette but acknowledges no other substance use. She denies sexual activity with others and denies any history of abuse or suicidal ideation.

On physical exam, you note that she has lost 9 kg (20 lbs) since her last well teen exam a year ago. Her height is at the 50th percentile for age and her weight is now at the 10th percentile for age. Other than being very thin, the only other abnormality in her physical exam is a heart rate of 44 beats per minute. She had normal dentition, no lanugo hair, and a Sexual Maturity (Tanner) Rating of V. She denies any feeling of being too thin or too fat.

On a separate interview with her parents, you discover that they have been concerned about her losing weight since she began "eating healthier" over the past several months. She also seems "almost obsessive" in her physical activity, taking part in paddling, track, tennis and aerobic exercises at home. They believe she is no longer having menstrual periods. There has been no evidence of any binging or purging behaviors.

Eating disorders include anorexia nervosa, bulimia nervosa, binge-eating disorders and a number of disordered eating variants. The Diagnostic and Statistical Manual IV (DSM-IV) criteria for anorexia nervosa include an excessive concern with body weight and shape, an intense fear of gaining weight and an obsessional preoccupation with food and eating (1). Additional criteria include either excessive weight loss or failure to gain weight as expected in a pubertal child, accompanied by secondary amenorrhea or a failure to achieve menarche. Bulimia nervosa involves repeated episodes of binge eating, often accompanied by purging (self-induced vomiting, and laxative or diuretic use). Binge eating disorder consists of repeated consumption of very large amounts of calorie dense foods in a short period of time without subsequent purging. Variant eating disorders would include those in which an individual does not express dissatisfaction with weight or body shape or in which menstrual periods remain unaffected by weight loss. Anorexia nervosa and bulimia nervosa appear to represent a spectrum of disordered eating. At least half of the patients with anorexia nervosa engage in binge eating/purging and many patients with bulimia nervosa experience periods of significant caloric restriction.

It is believed that anorexia nervosa and bulimia nervosa have existed in Western societies for centuries. However, there has been an apparent increase in both since the late 1960's. They appear to be more prevalent in modern industrialized societies throughout the world. In the U.S., they occur in all socioeconomic classes and ethnic groups. Anorexia nervosa typically has an onset in adolescence or in early adulthood and is more common in females, with a prevalence rate of about 0.5% among 15 to 19 year old adolescent girls (2). The prevalence among adolescent males is much lower, although males make up as much as 40 percent of individuals with binge eating disorders. The prevalence of bulimia nervosa is less certain, but surveys indicate that 10 to 50 percent of young females engage in periodic self induced vomiting or binge eating. While about 3 percent of females have anorexia nervosa, bulimia nervosa or binge eating disorder based on strict DSM-IV criteria, at least 20 percent are considered to have some degree of disordered eating. This fact is important because the clinician should be prepared to intervene early, before all DSM-IV criteria are met.

The cause of eating disorders is multifactorial (3). Genetic predisposition, neurochemical factors, psychological factors and sociocultural influences all have been implicated in the onset of disordered eating.

It is also important to recognize the high incidence of psychiatric comorbidities among patients with eating disorders. These include mood disorders, obsessive-compulsive traits, perfectionist traits, social isolation, and impulsive tendencies (e.g., related to sex and drugs).

Signs and symptoms related to anorexia nervosa are primarily those resulting from starvation and malnutrition, and can affect nearly every organ system. For patients engaged in bulimic as well as restrictive eating behaviors, additional signs and symptoms related to binge eating and purging may be present. The most frequent and obvious physical sign of anorexia nervosa is significant weight loss leading eventually to profound cachexia. Other frequent signs include bradycardia, cardiac arrhythmia, hypotension, hypothermia and dehydration. Dry skin, brittle hair, and lanugo hair are also frequently noted. While many patients may deny any symptoms, despite significant cachexia, some will acknowledge weakness, fatigue, lightheadedness, headaches, palpitations, abdominal pain, constipation, cold intolerance and amenorrhea. Some patients will not express a distorted body image early in treatment, saying their weight loss is due to forgetting or being too busy to eat. However, as treatment begins and weight gain occurs, the underlying fear of gaining weight often becomes very evident. Pubertal delay and bone fractures due to osteopenia are possible, although infrequent sequelae to prolonged starvation. Laboratory studies, which are frequently normal, may reveal anemia, leukopenia, thrombocytopenia, hypercholesterolemia and mild elevation of hepatic enzymes. Hyponatremia secondary to water-loading is not uncommon.

Patients with bulimia nervosa are frequently normal weight for height or may be overweight. Those with periodic restriction may experience dramatic fluctuation in weight. Many patients with binge eating and purging behaviors may have a completely normal physical exam. Those signs and symptoms generally associated with these behaviors include dental erosions, parotid swelling, pharyngitis, chest pain (esophagitis), abdominal pain, hematemesis, and calluses or abrasions on the dorsum of the hand from self-induced vomiting. With significant purging behavior (vomiting, laxative, or diuretic use) electrolyte abnormalities, usually reflecting a hypochloremic hypokalemic metabolic alkalosis, and dehydration are common.

The differential diagnosis of weight loss in an adolescent is long (4). It includes malignancy and a variety of chronic illnesses including diabetes mellitus, hyperthyroidism, malabsorption syndromes, systemic lupus erythematosus, inflammatory bowel disease, and psychiatric disorders such as major depression and substance abuse. However, in most cases, information gathered from the history, physical examination and evaluative studies makes the diagnosis of anorexia nervosa relatively easy. For example, a patient (or patient's parents) who gives a history of a daily diet of only lettuce, tomatoes and rice cakes and who, despite a 10 kg (25 lb) weight loss, reports running 10 miles three times a week, is unlikely to have cancer or any of the other disorders listed above. On the other hand, it is important to remember that a patient with disordered eating may also develop diabetes or hyperthyroidism.

The differential diagnosis of binge eating with purging is much shorter, but may include other psychiatric conditions. If a patient denies willfully induced vomiting, the differential diagnosis includes a variety of gastrointestinal and metabolic disorders. Nevertheless, these latter conditions do not usually involve binge eating or lead to the kind of surreptitious vomiting engaged in by adolescents with bulimia nervosa.

In approaching the differential diagnosis it is important not to rely only on the adolescent patient's history. Many patients with anorexia nervosa will not report feelings of being fat or desiring to lose weight. Similarly, most patients with bulimia nervosa initially deny any bulimic behaviors. Parental observations of the patient's eating and purging behaviors or expressions of dissatisfaction with weight or body shape are invaluable on these cases.

Having made the diagnosis of an eating disorder, the first decision in treatment is whether the patient is in a life-threatening situation that requires either medical or psychiatric hospitalization. Medical hospitalization is generally indicated if there is evidence of significant cardiac compromise reflected in significant bradycardia, arrhythmia or hypotension. Electrolyte abnormalities such as hypokalemia or hyponatremia also place the patient at significant risk. Electrolyte disturbance and dehydration are relatively easy to correct through intravenous fluid and electrolyte supplementation. Continuous cardiac monitoring is also available in the hospital setting. Whether treatment begins in an ambulatory or an inpatient setting, an immediate goal is to increase nutrient intake. This can be done orally with a carefully devised meal plan or, if this is refused, through nasogastric feedings or hyperalimentation in the hospital setting. Treatment usually involves institution of an "Eating Disorder Protocol" in which normalized eating and weight gain is rewarded with increased privileges and non-compliance results in removal of privileges or hospitalization. The protocol also provides incentives for decreasing bulimic behaviors.

The treatment team often includes a psychiatrist, a pediatrician, a dietitian as well as the patient and her or his family. Because eating disorders are chronic in nature, the eating disorder team has a long term commitment to work with the adolescent patient and her/his family. The role of the pediatrician is to regularly monitor the patient's physical status during the stage of refeeding and weight gain. The dietitian provides counseling on appropriate nutrition and structural goals and guidelines to assure this occurs. The psychiatrist provides supportive care during the early stages of refeeding, and later begins the important work of facilitating increased self understanding as to the origins of the patient's disordered eating and provide therapy aimed at addressing those issues (5).

The long term prognosis for adolescent patients with anorexia nervosa is guarded at best (6). A recent review of follow-up studies of patients with this disorder found that only 44 percent had a good outcome (normalized weight for height and return of menstrual periods). Twenty-four percent had a poor outcome (failure to achieve normal weight for height and continued menstrual irregularities). Twenty-eight percent had an intermediate prognosis between "good" and "poor." Mortality was 5 percent overall. Suicide is the most frequent cause of death in patients with anorexia nervosa, followed by cardiac arrest and other medical complications related to starvation and/or binging or purging. The best prognosis occurs in patients with early onset of the disorder, less weight loss, no purging behavior, and healthy family functioning prior to onset of the disorder. Anorexia nervosa is often accompanied by other psychiatric conditions, and studies have found that patients responding well to treatment for their eating disorder may continue to experience depression, anxiety, obsessive-compulsive traits, social phobia and substance abuse.

Prognosis related to bulimia nervosa is less certain since many individuals with this disorder do not enter treatment. There is some evidence that even without treatment the rate of spontaneous remission may be as high as 30 to 40 percent over a one to two year period. With treatment, a positive outcome may be as high as 50 to 70 percent, although the relapse rate may also be high. One study of patients with bulimia nervosa who had successful results from intensive treatment showed that 60 percent continued to have good results at 6 years following treatment (7). Mortality was only 1 percent. Death is generally related to cardiac effects of hypokalemia due to purging behavior. Prognosis may be poor for patients with more frequent vomiting prior to entering treatment.

Questions

1. What is the leading cause of death in patients diagnosed with anorexia nervosa?

2. What is the most likely electrolyte abnormally in patients with bulimia nervosa who engage in self induced vomiting?

3. Name three indications for medical hospitalization of a patient with an eating disorder.

4. A teenaged female reports feeling healthy, denies feeling fat, and has normal menstrual periods. However, she has evidenced a 20 lb. weight loss. What is the most likely diagnosis?

5. Name six possible conditions or disorders on the differential diagnosis of excessive weight loss in an adolescent.

6. Which disorder is most likely to present with a normal physical exam, anorexia nervosa or bulimia nervosa?

References

1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, edition 4. 1994, Washington, DC: American Psychiatric Association.

2. Fisher M, Golden NH, Katzman DK, et al. Eating disorders in adolescents: A background paper. J Adol Health 1995;16(6):420-437.

3. Becher AE, Grinspoon SK, Klibanski A, et al. Eating disorders. New Engl J Med 1999;340(14):1092-1098.

4. DeZwaan M, Mitchell JE. Medical evaluation of the patient with an eating disorder. In: Mehler PS, Andersen AE (eds). Eating Disorders. 1999, Baltimore: The John Hopkins University Press, pp. 44-62.

5. American Psychiatric Association. Practice guidelines for the treatment of patients with eating disorders (revision). Am J Psychiatry 2000;157(1):1-30.

6. Kreipe RE, Uphoff M. Treatment and outcome of adolescents with anorexia nervosa. Adolescent Medicine: State of the Art Reviews 1992;3(3):519-540.

7. Keel PK, Mitchell JE. Outcome in bulimia nervosa. Am J Psychiatry 1997;154:313-321.

Answers to questions

1. Suicide is the leading cause of death in anorexia nervosa. The second highest cause of death is cardiac arrest.

2. Patients who self induce vomiting are most likely to develop a hypochloremic hypokalemic metabolic alkalosis.

3. Three indications for hospitalization of a patient with anorexia nervosa include: a) electrolyte abnormalities (hypokalemia, hyponatremia), b) cardiovascular abnormality (bradycardia, arrhythmia, hypotension), c) inability or refusal to engage in outpatient treatment.

4. The most likely diagnosis is anorexia nervosa. The point is that the most likely cause of significant weight loss in an adolescent female is an eating disorder, even if DSM-IV criteria are not completely met.

5. Disorders other than anorexia nervosa in the differential diagnosis of excessive weight loss in an adolescent include malignancy, diabetes mellitus, hyperthyroidism, malabsorption syndromes, systemic lupus erythematosus, inflammatory bowel disease, depression and substance use.

6. Bulimia nervosa is more likely to present with a normal physical exam. By definition, anorexia nervosa must show weight loss or a failure to gain weight appropriately during puberty.