Recognizing, managing medical consequences of eating disorders in primary care
ABSTRACTEating disorders can lead to serious health problems, and as in many other disorders, primary care physicians are on the front line. Problems that can arise from intentional malnutrition and from purging affect multiple organ systems. Treatment challenges include maximizing weight gain while avoiding the refeeding syndrome.
KEY POINTS
- The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), released in 2013, has updated the criteria for some eating disorders and has added some new disorders.
- Starvation can cause cardiac, cerebral, gastrointestinal, and endocrine problems.
- Purging can lead to problems with oral health, electrolyte imbalances, and even renal failure.
- Refeeding poses the risk of refeeding syndrome, with fluid overload and electrolyte imbalances. Many patients undergoing refeeding are best managed in the hospital.
COMPLICATIONS OF PURGING
Oral complications of purging
Patients who purge by vomiting are at risk of complications from exposure of the esophagus, pharynx, and mouth to acidic gastric contents.
Dental problems. Over time, contact with gastric acid wears down enamel on the lingual and occlusal surfaces of teeth, resulting in dental caries and periodontal disease. Until they can give up purging, patients should be instructed to rinse with mouthwash or water immediately after vomiting to reduce the acidity in the mouth.41,42 We recommend that patients not brush their teeth after vomiting, because brushing can deliver acid to otherwise unreachable surfaces and thus worsen tooth erosion. For patients who are determined to brush after vomiting, a bicarbonate toothpaste might mitigate harm.42
Sialadenosis (hypertrophy of the salivary glands) is another consequence of repeated vomiting, with elevated salivary amylase. Both the size of the glands and the salivary amylase level generally normalize on their own after vomiting is stopped, but parotitis can take up to a year to resolve. Similar to smoker’s cough, parotitis may acutely worsen when the patient abruptly stops vomiting and may worsen before it improves.
To reduce discomfort, patients can use hot compresses or sugarless hard candies.44 However, the latter should not be substituted as a chronic habit in a patient with disordered eating. Patients need to be reassured that the swelling is not permanent, since they often interpret it as having fat cheeks (the “chipmunk sign”).
Hypokalemia, metabolic alkalosis, renal dysfunction
Chronic vomiting can cause electrolyte and acid-base imbalances, the most worrisome of which is hypokalemia. With repeated vomiting, loss of potassium and gastric acid causes metabolic alkalosis with hypokalemia, hypochloremia, and hypomagnesemia. Loss of water and the resultant volume contraction activates the renin-angiotensin-aldosterone system, and elevated aldosterone further decreases serum potassium.
In patients with eating disorders, who often have other factors contributing to electrolyte imbalance, vomiting-induced hypokalemia heightens the risk of cardiac arrhythmias.43
Hypokalemia can also cause rhabdomyolysis and kidney damage.41,43 Prolonged hypokalemia and reduced kidney perfusion in the setting of volume depletion causes acute kidney injury and impaired concentrating ability of the renal tubules. Hypovolemia can cause prerenal azotemia and increases the risk for nephrolithiasis and nephrocalcinosis.44,45
When a patient stops vomiting, elevated aldosterone from prior hypovolemia results in water retention and can manifest in significant edema associated with hypochloremic alkalosis. This condition, known as pseudo-Bartter syndrome, usually resolves without treatment. In the meantime, salt restriction and leg elevation can help reduce edema.26
Laxative abuse: A mode of purging
Many patients with eating disorders abuse laxatives to lose weight or to prevent weight gain. Believing that laxatives will prevent calorie absorption, patients commonly take them to compensate for caloric intake (eg, during a binge episode). The immediate weight loss, albeit artificial, is highly reinforcing for an eating-disorder patient. In some cases, patients with eating disorders also abuse laxatives to self-treat the constipation that results from chronic starvation.46
Over time, tolerance to laxatives develops, and patients use increasingly larger doses. This can lead to activation of the renin-angiotensin-aldosterone system.47 Patients interpret the resultant edema as true weight gain and again take laxatives to get rid of it. If laxatives are stopped abruptly, the patient may need inpatient and outpatient support for the resultant fluid shifts.
Gastrointestinal complications of laxative abuse include reflex hypofunction of the bowel, malabsorption, steatorrhea, and gastrointestinal bleeding.47 Reflex hypofunction during laxative withdrawal is a consequence of the bowel becoming tolerant of laxatives.48 Cathartic colon syndrome is a rare complication characterized by loss of the normal haustral markings and slowed or absent peristalsis in segments of the colon.49
Systemically, the major risk of laxative abuse relates to electrolyte and acid-base imbalance. Loss of potassium and water in the stool can cause hypokalemia and metabolic alkalosis.48 The disturbances caused by laxative abuse are similar to those caused by vomiting and diuretic use and have the same treatment.
The most important component of treating laxative abuse is giving patients realistic expectations to help them tolerate temporary discomfort and to help manage the edema and fluid shifts that can happen acutely with shifting of fluid into the intracellular space. In extreme cases, this may need to be managed in the hospital. To help relieve the initial anxiety, doctors should emphasize that any bloating the patient experiences is not true weight gain and will go away within a few days to weeks. In addition, explaining that laxatives reduce nutrient absorption only minimally may lessen the temptation to resume taking them.48
Diuretic abuse: Another form of purging
Diuretic abuse is yet another mode of purging, with its own set of medical complications. Like laxatives, diuretics are not effective weight-loss agents, and the weight reduction they cause is only temporary.
As with vomiting, there is a compensatory activation of the renin-angiotensin-aldosterone system, and therefore subsequent fluid intake will lead to water retention, which encourages further diuretic use.41 Diuretics can also contribute to hypokalemia, hypomagnesemia, hypochloremia, and metabolic alkalosis.
Ipecac abuse can lead to heart failure
Ipecac syrup has long been used to induce vomiting, but this practice has become much less common since ipecac has become harder to obtain in the United States.50 The emetine base contained in ipecac binds irreversibly to cardiac and skeletal muscle. With continued use, irreversible cardiomyopathy develops and can lead to heart failure. Treatment should include supportive care and immediate cessation of ipecac use.
Diabetic patients may skip insulin to lose weight
Patients with diabetes, especially those with type 1 that begins in childhood, are at greater risk of eating disorders over time.51 They may withhold insulin to lose weight, a practice referred to in the nonmedical literature as “diabulimia,” and they seem particularly more likely to develop bulimia nervosa than those without diabetes.52
The medical prognosis is poor for patients with diabetes who develop eating disorders and do not receive intensive treatment.51 In addition, if a diabetic patient on an insulin pump becomes depressed in addition to having an eating disorder, careful monitoring for suicidal thoughts and a rapid follow-up with mental health services are in order.
