Anorexia nervosa, bulimia and binge eating disorder affect up to 5% of young women, are associated with high use of medical resources, but often go unrecognized in medical settings. Men with eating disorders are even more likely to elude detection. All physicians should be alert to signs and symptoms of these relatively common behavioral disorders. Most cases respond to specialist treatment, although rates of medical morbidity, functional impairment and mortality are high, especially for anorexia nervosa, which has the highest mortality of any psychiatric condition. Patients may deny they have an eating disorder; and some degree of symptom concealment is common, as these conditions are associated with high levels of ambivalence towards treatment, as well as feelings of shame, embarrassment and stigma. 

Patients frequently present to a variety of medical specialists including pediatricians, internists, gastroenterologists, endocrinologists, gynecologists, neurologists, cardiologists, orthopedic specialists and psychiatrists seeking help for medical or psychiatric complications of their eating behavior, whether or not they acknowledge their diagnosis. They may avoid treatments focused on normalizing their eating behavior, favoring instead medical interventions that address consequences of their behavior without altering the underlying problem. 

Medical professionals should be familiar with common presenting complaints, with diagnostic screening questions and with treatment options to optimally detect and manage these disorders. Collateral information from family is often very helpful in establishing the diagnosis. Onset of an eating disorder may be insidious, and may follow a viral or other illness. It is not uncommon for example for a bout of mononucleosis or viral gastroenteritis to evolve into anorexia nervosa or bulimia.

Complications of eating disorders are best thought of as consequences of starvation or of bingeing and purging behaviors. Patients who are underweight and who purge are therefore at highest risk for severe complications.

Eating disorders can affect all organ systems and presenting complaints are quite varied. The following Top 10 list reviews common medical presentations and laboratory values that may reflect an occult eating disorder. The vast majority of these symptoms reverse with normalization of weight and eating behavior, although symptomatic treatment alone is unlikely to alter their course, making identification and appropriate referral for treatment of the underlying behavioral disorder of paramount importance.

1. Metabolic or electrolyte abnormalities

• Rapid weight loss may indicate anorexia nervosa and rapid weight gain may result from new onset binge eating disorder
• Hypokalemia can be a sign of regular self-induced vomiting, especially in the presence of low chloride and elevated bicarbonate. Laxative abuse may also lead to hypokalemia and can result in either metabolic acidosis or alkalosis. Diuretic abuse can result in hypokalemia and contraction alkalosis. 
• Hypoglycemia may be starvation-related in anorexia nervosa
• Hyponatremia may result from excessive water intake, a behavior often used to suppress appetite and increase satiety or to artificially inflate weight gain.
• Hypophosphatemia may be detected on initial evaluation following weight loss, although more commonly a complication of refeeding

2. Gastrointestinal complaints

• Functional gastrointestinal disorders are present in the vast majority of inpatients with eating disorders treated on specialty behavioral units. Patients may also present with excessive and disabling preoccupations or idiosyncratic ideas regarding food intolerances or bowel regimens. Delayed gastric emptying and slowed whole gut transit times are typical of anorexia nervosa and gastroparesis is also commonly present in bulimia. 
• Abdominal bloating, pain and constipation and other symptoms typical of irritable bowel syndrome are frequently associated with starvation or with binge intake of food.
• Gastrointestinal reflux disease (GERD), esophageal Mallory Weiss tears, bilateral parotid gland enlargement, dental caries and enamel erosion are all associated with self-induced vomiting. Most individuals who vomit regularly have lost the gag reflex and many can vomit spontaneously without inducing a gag. 
• Transaminitis and elevated lipase and amylase are frequent consequences of anorexia nervosa and can be associated both with both starvation and refeeding.
• Acute gastric dilatation is a rare, life threatening presenting symptom in patients with anorexia nervosa who binge eat and may cause superior mesenteric artery syndrome.
• Rectal prolapse and hemorrhoids can be complications of laxative abuse.

3. Gynecologic and Obstetric complaints

• Hypothalamic amenorrhea and infertility are common in anorexia nervosa.
• Pregnancy may be associated with poor weight gain, intrauterine growth retardation or hyperemesis gravidarum in individuals who purge by vomiting.
• Postpartum rapid weight loss due to excessive breast pumping and milk wasting has been described. 

4. Neurologic presentations

• Syncopal or presyncopal episodes and orthostasis due to fluid restriction or diuretic and laxative abuse may be presenting symptoms.
• Somatoform pain disorders especially abdominal pain complaints or headaches are common.
• Seizures may be due to hypoglycemia or to excessive water intake and resultant hyponatremia.
• Wernicke-Korsakoff’s syndrome can be a complication of refeeding in very low weight anorexia nervosa, especially when comorbid with alcohol abuse. Preventative thiamine supplementation is critically important in these cases.

5. Cardiac presentations

• Bradycardia is often detected in anorexia nervosa and can be severe with heart rates of 30 or below and may be associated with QTc prolongation and increased risk of cardiac arrest.
• Orthostatic hypotension or tachycardia may reflect dehydration from purging or fluid restriction or from impaired vagal tone.
• A starvation cardiomyopathy and heart failure may occur in severe and chronic AN.
• Mitral valve prolapse due to atrophic cardiac muscle may be evident on exam.
• Arrthymias may occur due to electrolyte abnormalities or caffeine or ephedrine diet suppressant abuse.

6. Endocrine presentations

• Hypothalamic amenorrhea and infertility, as well as osteoporotic fractures are complications of anorexia nervosa. 
• Sick euthryoid labs are commonly seen in anorexia nervosa with low T3 and rT3 and ration of T4 to rT3 is elevated. TSH and T4 may be suppressed. 
• Hypercortisolemia is common in anorexia nervosa as a result of starvation related activation of the HPA axis and may contribute to bone loss and osteoporosis.
• Frequent ketoacidosis in a diabetic may reflect purging by underdosing insulin or insulin omission in order to waste calories.

7. Hematological presentations

• Anemia, leukopenia and thrombocytopenia are all seen in severe anorexia nervosa as starvation is associated with bone marrow hypocellularity and fatty infiltration.

8. Psychiatric complications

• Major depression, anxiety disorders and substance abuse are commonly comorbid with eating disorders and tend to worsen with the severity of the eating disorder.

9. Renal presentations

• Although relatively uncommon, renal failure can be seen in cases of severe laxative and or diuretic abuse. Contraction alkalosis and dehydration may be evident. In starvation, blood urea nitrogen may be very low due to low protein intake and 24-hour creatinine clearance is often decreased and is lower for laxative abusers than for pure restrictors.

10. Opportunistic Infections

• At severely low BMIs patients with anorexia nervosa can present with opportunistic infections. Case reports include mycobacterial infections and aspergillosis.

Tips to Diagnosing an Eating Disorder

• Asking questions about eating behavior and weight concerns is critical to making the diagnosis when an eating disorder is in the differential, the history should include direct questions that assess dieting behavior, binge eating, self-induced vomiting or regular laxative, diuretic or diet pill use in the service of weight control. Affirmative answers should be followed by clarifying questions regarding frequency and severity of each behavior. Collateral history from family regarding changes in exercise, dieting, bingeing or purging behaviors and weight or shape concern can be very helpful in confirming the diagnosis.
• Several screening instruments exist. The SCOFF is a rapid four question screening tool with good sensitivity and specificity that is easily included in a routine medical history. 
• Additional probes for anorexia nervosa include questions regarding desired weight --- “What would you like to weigh?” and dietary habits -- “Tell me what you eat at each meal on a typical day”. A desired maximum weight below a BMI of 19 in an adult is suggestive of anorexia nervosa. In anorexia nervosa and in bulimia the dietary repertoire is characterized by skipped meals and limited food choices, typical food choices are of low calorie density and fat content. In patients who binge, binges are usually secretive and involve intake of large quantities of high calorie density foods associated with a sense of loss of control over eating. 
• Patients usually have tried and failed to change on their own. They may be demoralized and discouraged. The physician should reinforce that treatment is effective and refer patients to an eating disorder specialist. As an integral member, and often the coordinator of the treatment team, physicians can be instrumental in engaging the reluctant or anxious patient in seeking appropriate treatment. 

The ‘‘SCOFF’’  

S   Do you make yourself SICK (vomit) because you feel uncomfortably full?

C   Do you worry that you have lost CONTROL over how much you eat?

O   Have you recently lost more than ONE stone (14 pounds) in a 3-month period?

F    Do you believe yourself to be FAT when others say you are thin?

F    Would you say that FOOD dominates your life?

Cut off: 2 or more abnormal responses has sensitivity of 100%, specificity of 87.5% for an eating disorder.

Reference: Morgan JF1, Reid F, Lacey JH., The SCOFF questionnaire: assessment of a new screening tool for eating disorders. BMJ. 1999 Dec 4;319(7223):1467-8.