Eating disorders are among the most common psychiatric problems that affect young women,¹ and these conditions impose a high burden of morbidity and mortality. Unfortunately, the diagnosis of eating disorders can be elusive, and more than one half of all cases go undetected.² The family physician's office is an ideal setting to identify eating disorders and initiate treatment in a timely fashion. This review focuses on recognition and diagnosis of eating disorders in primary care. A comprehensive review of treatment and other aspects of these conditions is available in the American Psychiatric Association's practice guideline on the treatment of eating disorders.³

Epidemiology

Eating disorders occur most commonly in adolescents and young adults and are 10 times more common in females than in males. They occur in all ethnic groups but are most common among whites in industrialized nations. The principal eating disorders are anorexia nervosa, bulimia nervosa, and nonspecified eating disorder. Anorexia has two subtypes—restricting type and binge-eating/purging type. Bulimia also has two subtypes—purging and nonpurging.

In young women, the risk of developing anorexia is 0.5 to 1 percent, and mortality is estimated at 4 to 10 percent.^4,5 In the same population, the risk of developing bulimia is 2 to 5 percent,^1,6 and the incidence of disordered eating that does not meet strict criteria for eating disorders may be twice that of the above conditions.² Frequent dieting and desire for weight loss occur much more commonly than overt eating disorders. In 1999, the Youth Risk Behavior Surveillance Survey⁷ reported that 58 percent of students in the United States had exercised to lose weight, and 40 percent of students had restricted caloric intake in an attempt to lose weight. Many adolescents and young adults who do not meet the strict diagnostic criteria for eating disorders have disordered eating patterns, which can have a significant adverse impact on health. The distinction between normal dieting and disordered eating is based on whether the patient has a distorted body image.

Etiology

Risk factors for developing an eating disorder include participation in activities that promote thinness, such as ballet dancing, modeling, and athletics,⁴ and certain personality traits, such as low self-esteem, difficulty expressing negative emotions, difficulty resolving conflict, and being a perfectionist.¹ Eating disorders are particularly common in young women with type 1 diabetes mellitus. Up to one third of women with type 1 diabetes may have eating disorders, and these women are at especially high risk of microvascular and metabolic complications.⁸

The role of family history in the development of eating disorders is not clear. Some studies⁹ of twins demonstrate a strong link, and others demonstrate no correlation. A family history of mood disorders in a first-degree relative also might be a risk factor.⁵

Diagnosis

Early diagnosis with intervention and earlier age at diagnosis are correlated with improved outcomes in patients who have eating disorders.⁵ Because family physicians serve as primary care providers for a large percentage of adolescents, they have an important role in diagnosing these disorders.

The hallmark of anorexia is a refusal to maintain body weight at or above 85 percent of expected weight, as defined by age-appropriate body mass index charts. Patients with anorexia use caloric restriction or excessive exercise to control emotional need or pain, and they are terrified of becoming overweight. Patients with nonpurging-type bulimia also might severely restrict calories or exercise excessively to lose weight but do not meet the weight criteria for diagnosis of anorexia.

Bulimia is characterized by uncontrollable binge-eating episodes, often followed by purging behaviors such as vomiting or the use of laxatives. Patients with binge-eating/purging-type anorexia also might binge and purge. Patients who have bulimia may be of normal weight, or they may be under- or overweight, whereas patients with binge-eating/purging-type anorexia are underweight.

Both of the major eating disorders are characterized by a disturbance in the perception of body shape, which is closely tied to self-image. Summaries of diagnostic criteria for anorexia and bulimia are provided in Tables 1 and 2.¹⁰ It is also important to aggressively treat patients who have traits of eating disorders but who do not meet the full criteria for anorexia or bulimia.¹¹

Differential Diagnosis

A wide variety of medical problems can masquerade as eating disorders. Hyperthyroidism, malignancy, inflammatory bowel disease, immunodeficiency, malabsorption, chronic infections, Addison's disease, and diabetes should be considered before making a diagnosis of an eating disorder. Most patients with a medical condition that leads to eating problems express concern over their weight loss. However, patients with an eating disorder have a distorted body image and express a desire to be underweight.¹⁰

Psychiatric comorbidity is extremely common; illnesses such as affective disorders, obsessive-compulsive disorder, somatization disorder, and substance abuse must be considered when patients present with such symptoms.¹²

Major depression is the most common comorbid condition among patients with anorexia, with a lifetime risk as high as 80 percent.⁵ Anxiety disorders, especially social phobia, also are common.⁵ Obsessive-compulsive disorder has a prevalence of 30 percent among patients with eating disorders.¹³ Substance abuse prevalence is estimated at 12 to 18 percent in patients with anorexia and 30 to 70 percent in patients with bulimia.¹⁴

Personality disorders (Axis II diagnoses) also are common, with comorbidity rates reported at 21 to 97 percent.¹⁵ The wide range is related to the complexity of evaluating these diagnoses. Patients with bulimia are more likely to have a cluster B diagnosis (dramatic/erratic), whereas patients with anorexia are more likely to have a cluster C diagnosis (avoidant/anxious).¹⁵

Screening Tools

All patients in high-risk categories for eating disorders should be screened during routine office visits.¹⁶ The medical history is the most powerful tool for diagnosing eating disorders. Physical examination and laboratory findings might be normal, especially early in the course of eating disorders.

A number of comprehensive psychiatric interviews can be used to diagnose eating disorders,^17,18 but these are impractical in the primary care setting. One promising screening tool is the SCOFF questionnaire (Table 3).¹⁹ Because of its 12.5 percent false-positive rate, this test is not sufficiently accurate for diagnosing eating disorders, but it is an appropriate screening tool.

Other screening questions that might be helpful are listed in Table 4.^18,20 Positive responses to any of these questions should prompt further investigation with a more comprehensive questionnaire. When screening patients, it is important to take their developmental stage into account; some questions might be inappropriate for younger patients.

History and Presenting Symptoms

Patients with eating disorders can have a wide range of symptoms. Those with milder illness might have nonspecific complaints, such as fatigue, dizziness, or lack of energy.⁴ Patients might deny that they have symptoms, but their family members might express concern. Patients who have anorexia typically will be unconcerned about significant weight loss. Other symptoms that might be reported or elicited include amenorrhea, sore throat, gastroesophageal reflux disease, abdominal pain, cold intolerance, constipation, polyuria, polydipsia, and palpitations. When taking a medical history, it is also important to take a dietary history to ask about the use of laxatives or diuretics. Table 5 compares important clinical features of anorexia and bulimia.

When obtaining a history, it is important to establish trust and rapport with the patient, especially when the patient does not perceive a problem. Talking to the family and patient together, as well as talking to the patient individually, is appropriate. If the patient is an adolescent, questions must be asked in a developmentally appropriate, precise, non-judgmental way.²¹

Physical Examination

Complications of anorexia and bulimia can affect nearly every organ system. However, many patients might have a completely normal physical examination, especially early in the disorder. It is important to explain to patients and their families that a normal physical examination does not rule out an eating disorder.

Accurate weight measurements are important in diagnosing an eating disorder. Abnormal growth curves, especially in children and adolescents, can be revealing. A patient who initially had normal growth parameters might stop gaining weight or might lose weight while height increases. Eventually, height will be affected, and growth will diminish.

To obtain accurate weight measurements, office staff must be trained to use standardized protocols to record consistent, reliable measurements. Scales should be located in a private area, and comments about weight should be minimized and made discreetly. Staff should be aware that some patients with eating disorders, to avoid revealing their true weight, might drink extra fluids, put weights in their pockets, or wear layers of heavy clothing before being weighed.¹

Vital signs might be abnormal, such as bradycardia, orthostatic hypotension, and hypothermia. Abnormal skin findings include dry skin, loss of subcutaneous fat, lanugo (fine body hair), and hypercarotenemia (an orange hue caused by increased ingestion of carrots). Patients who induce vomiting might have calluses on the dorsum of the dominant hand, as well as loss of dental enamel. Salivary gland enlargement is another sign of purging behavior.

Pulmonary complications of eating disorders are rare, but vomiting can cause a pneumomediastinum. Pulmonary edema may occur in patients who undergo refeeding. In addition to bradycardia, cardiac findings may include acrocyanosis and decrease in overall heart size and stroke volume. Cardiomegaly can indicate ipecac use. Electrocardiogram findings may include bradycardia, prolonged QT interval, and nonspecific ST-T changes.

The gastrointestinal system also can be adversely affected. There can be decreased bowel motility, leading to abdominal distension. Gastroesophageal reflux and pancreatitis can cause epigastric pain. If the patient is constipated, stool might be palpable in the left lower quadrant.

Laboratory Evaluation

Laboratory findings might be completely normal, but targeted laboratory testing can be helpful to rule out medical illness. In patients who have eating disorders, the complete blood cell count might be normal, but leukopenia is not uncommon, probably because of increased margination of neutrophils. Immune function does not appear to be impaired. In severe cases, pancytopenia might be present.¹² Blood glucose levels might be low.² Hypochloremic, hypokalemic, or metabolic alkalosis might be present in patients who purge. Hypokalemia also might result from diuretic and laxative use. Severe hypokalemia might lead to cardiac arrhythmias, muscle weakness, or confusion. Hyponatremia might occur with excessive water intake. Thyroid-function test findings might be consistent with the euthyroid sick syndrome, with low triiodothyronine and thyroxine levels and a normal thyroid-stimulating hormone level.

Osteopenia in eating disorders can result from several factors. Decreased estrogen levels and inadequate micronutrients, especially during adolescence when bone strength is typically increasing, can lead to clinically significant osteopenia after as few as six months of illness.² It is worthwhile to obtain dual-energy x-ray absorptiometry scans after six months of amenorrhea in patients with anorexia and in patients with bulimia who have a history of anorexia.¹²

Treatment

Treatment intensity and setting depend on the severity of the illness. Patients with mild illness can be managed on an outpatient basis. Patients who are medically or psychiatrically unstable require inpatient treatment (Table 6).³ [Evidence level C, expert opinion] Treatment goals include attainment and maintenance of a healthy weight, management of physical complications, management of comorbid psychiatric illness, and prevention of relapse. Eliciting cooperation from the patient, helping to change maladaptive thoughts, and educating the patient about proper health and nutrition also are important.³

Adequate treatment of eating disorders requires a multidisciplinary team approach. The family physician can and should be an integral member of that team. Early in the illness, frequent visits to the primary care physician's office are helpful for surveillance of medical conditions, as well as for nutritional re-education. The family physician also will be indispensable in the role of coordinating the entire team of professionals involved in the patient's care.

Prognosis

The prognosis of patients who have eating disorders is variable. The general consensus is that 50 percent of patients with anorexia have good outcomes, 30 percent have intermediate outcomes, and 20 percent have poor outcomes. The percentages are similar in bulimic patients, with 45 percent having good outcomes, 18 percent having intermediate outcomes, and 21 percent having poor outcomes. Patients with anorexia have a mortality rate six times that of peers without anorexia.⁵

Factors that predict improved outcomes for eating disorders include early age at diagnosis, brief interval before initiation of treatment, good parent-child relationships, and having other healthy relationships with friends or therapists.⁵

Because of the severity of these illnesses and the improvement in outcomes when diagnosis occurs earlier, the family physician can play a crucial role in helping patients recover from eating disorders by detecting them at an early stage.