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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
Key points
- Binge eating + compensatory behaviors at least weekly for 3 months
- Patients are usually normal weight or overweight; significantly low weight suggests anorexia
- Purging causes hypokalemic hypochloremic metabolic alkalosis, arrhythmias, dental erosion, parotid enlargement
- First-line: eating-disorder-focused CBT; fluoxetine 60 mg/day is FDA-approved
- Assess suicide, self-harm, substance use, and medical instability
Overview
Bulimia nervosa features recurrent binge eating with loss of control followed by vomiting, laxatives/diuretics, fasting, or excessive exercise. DSM-5-TR requires at least weekly episodes for 3 months and self-evaluation dominated by weight/shape.
Epidemiology
Bulimia often starts in adolescence/young adulthood and is associated with depression, anxiety, borderline traits, substance use, trauma, and impulsivity. Symptoms are often concealed and patients may present with dental, GI, or electrolyte problems.
Clinical Features
Symptoms
Binge episodes with loss of control
Vomiting, laxatives, diuretics, fasting, or excessive exercise
Shame, secrecy, guilt, weight/shape preoccupation
Sore throat, reflux, abdominal pain, constipation
Syncope, palpitations, hematemesis, severe weakness, suicidality
Signs
Normal weight or overweight common
Parotid enlargement, dental enamel erosion, Russell sign
Orthostasis, dehydration, arrhythmia, weakness from hypokalemia
Signs of laxative misuse
Investigations
First-line
DSM-5-TR assessmentBinge/purge frequency, duration >=3 months, loss of control, weight/shape overvaluation
LabsCMP including potassium/chloride/bicarbonate, Mg, phosphate, renal function, pregnancy
ECGHypokalemia, syncope, palpitations, QT risk, severe purging
Second-line
Dental/GI assessmentDental erosion, esophagitis, Mallory-Weiss tear, reflux, constipation
Psychiatric screenDepression, suicide, trauma, substance use, borderline traits
Food logs/scalesTreatment planning and monitoring
Specialist
Emergency/inpatient careSevere electrolytes, arrhythmia, syncope, hematemesis, suicidality
Eating disorder specialistCBT-E, dietitian, medical monitoring, medication
1
Medical
- Correct hypokalemia/dehydration; ECG monitoring when significant
- Treat esophagitis, dental complications, constipation
- Assess suicide and substance use
2
Psychotherapy
- Eating-disorder-focused CBT first-line
- Interpersonal psychotherapy alternative
- Family-based approaches for adolescents
3
Medication/nutrition
- Fluoxetine 60 mg/day reduces binge/purge behavior
- Avoid bupropion due to seizure risk
- Structured regular meals reduce restriction-triggered binges
Complications
- Hypokalemic metabolic alkalosis:
- Arrhythmias:
- Esophagitis/Mallory-Weiss tears:
- Dental enamel erosion:
- Depression/self-harm/substance use:
USMLE Step 2 CK Exam Tips
- 1Bulimia = binge/purge with normal/high weight; anorexia = significantly low weight
- 2Vomiting causes hypokalemic hypochloremic metabolic alkalosis
- 3Fluoxetine 60 mg/day is classic medication
- 4Bupropion contraindicated
- 5Russell sign = knuckle calluses
- 6Parotid enlargement/dental erosion are purging clues
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