Eating Disorders

1. THE 2-MINUTE PHYSIOLOGY (Rapid Pathophysiology)

• The Hemodynamic Collapse: In severe malnutrition associated with eating disorders, the core mechanical failure is a profound reduction in cardiac output secondary to myocardial atrophy and starvation.
• Pseudo-Bartter Syndrome: Repeated purging (vomiting) directly causes volume depletion and loss of gastric acid, leading to a classic triad of metabolic alkalosis, hypokalemia, and secondary hyperaldosteronism.
• Refeeding Syndrome: When nutrition is abruptly reintroduced to a starved patient, a massive insulin surge causes rapid intracellular shifts of electrolytes (especially phosphorus, potassium, and magnesium). This critical cellular depletion drives severe tissue hypoxia (shock), myocardial dysfunction, and respiratory failure due to the diaphragm's inability to contract.
• Binge Eating Metabolic Shifts: Binge eating disorder independently drives an increased risk of dyslipidemia, profound glucose dysregulation, and type 2 diabetes mellitus.

2. THE BEDSIDE ACTION PLAN (Rapid ER Management)

• Immediate Stabilization: Rapidly assess and support ventilation and circulation (ABCs).
• Judicious Fluid Resuscitation: Correct volume depletion and metabolic/electrolyte derangements with intravenous fluids. However, because cardiac output is significantly reduced in severe malnutrition, fluid replacement must be highly judicious to avoid precipitating acute iatrogenic heart failure or pulmonary edema.
• Psychiatric Safety: Immediately implement safety protocols and continuous observation if there is any concern for suicidality. Anorexia nervosa is the most lethal mental disorder, with 1 in 5 patients dying by suicide.
• Toxidrome Screening: Specifically screen for the occult abuse of over-the-counter weight-loss agents, including caffeine, herbal stimulants (e.g., ma-huang/ephedra), and thyroid supplements, which may require specific toxicological management.

3. THE DIAGNOSTIC GRID (Differential Diagnosis & Workup)

Medical illnesses perfectly mimic eating disorders and must be excluded in the ED.

• Critical "Can't-Miss" Differentials:
• Pregnancy (Classic mimic for amenorrhea and vomiting).
• Endocrine emergencies (Hyperthyroidism, Addison's disease, Diabetes Mellitus, Hypopituitarism).
• Central Nervous System (CNS) or other occult malignancies.
• Gastrointestinal malabsorption (Inflammatory Bowel Disease, Celiac disease).
• Prioritized Diagnostic Workup:
• Beta-hCG: Mandatory in females to rule out pregnancy as the cause of amenorrhea/vomiting.
• Comprehensive Metabolic Panel (CMP): Screen for hypokalemia, hypomagnesemia, and hypophosphatemia (critical in refeeding risk).
• Complete Blood Count (CBC): Look for anemia, mild leukopenia, thrombocytopenia, or increased hemoglobin reflecting severe hemoconcentration/dehydration.
• Urinalysis: Evaluate for severe dehydration or occult "water loading" (used by patients to artificially inflate scale weight).
• Toxicology: Serum/urine screening for illicit drugs, acetaminophen, salicylates, tricyclics, or ipecac if intentional ingestion or self-harm is suspected.

4. THE VISUAL BOARD (ECG / POCUS / Imaging)

An ECG is absolutely mandatory for patients who are severely symptomatic, malnourished, have electrolyte abnormalities, or have a history of ipecac abuse. Look explicitly for:

• Sinus Bradycardia: The most common cardiovascular abnormality.
• Prolonged QTc Interval: A rare but potentially lethal complication predisposing the patient to Torsades de Pointes.
• ST-Segment Depression: Often secondary to severe underlying electrolyte abnormalities (e.g., profound hypokalemia).
• Ischemic Changes: If ischemic ECG changes are seen in a young patient with an eating disorder, immediately suspect ipecac cardiotoxicity.
• Dysrhythmias: Evaluate for supraventricular ectopic beats and ventricular tachycardia.

5. THE SCORING MATRIX (Risk Stratification & Guidelines)

• The SCOFF Questionnaire: A validated 5-question rapid ED screening tool. >2 "yes" responses strongly suspect an eating disorder:
• Sick: Do you make yourself sick because you feel uncomfortably full?
• Control: Do you worry you have lost control over how much you eat?
• One stone: Have you recently lost more than one stone (14 lbs / 6.35 kg) in a 3-month period?
• Fat: Do you believe yourself to be fat when others say you are too thin?
• Food: Would you say that food dominates your life?
• Strict Admission Criteria (Physiologic Instability):
• Severe bradycardia: Heart rate < 50 bpm (or < 45 bpm while asleep).
• Hypotension: Blood pressure < 80/50 mm Hg.
• Severe hypothermia: Temperature < 96°F (< 35.6°C).
• Presence of orthostatic vital sign changes.
• Acute medical complications of malnutrition (syncope, seizures, pancreatitis) or uncontrollable multiple daily binge/purge episodes.

6. THE DANGER ZONE (Pitfalls & Critical Actions)

• The "Normal Lab" Premature Closure: A deadly cognitive trap is assuming a patient is medically stable because their blood work is unremarkable. The physical exam and laboratory tests can be entirely normal, especially early in the course of the illness.
• Aggressive Fluid Resuscitation: Administering standard rapid, large-volume IV fluid boluses (e.g., 30cc/kg) to a severely malnourished patient is a dangerous action that can rapidly precipitate cardiogenic shock due to an atrophied heart and reduced cardiac output.
• CRITICAL ACTION: Board examiners mandate that you perform a formal suicide risk assessment. Anorexia is the most lethal psychiatric disorder, and missing occult suicidality or severe comorbid depression leads to catastrophic outcomes.

7. MCQ MASTERCLASS (Written Exam Tips)

• High-Yield Buzzword: The presence of "Pseudo-Bartter syndrome" in a question stem (hypokalemia, metabolic alkalosis, and elevated aldosterone) is the classic biochemical signature of chronic vomiting/purging.
• The ECG Trap: A stem features a 19-year-old female with known bulimia presenting with chest pain, and her ECG shows acute ST-segment depressions and ischemic changes. The most likely cause is Ipecac abuse causing direct cardiotoxicity.
• The Distractor: A patient presents with a 3-month history of amenorrhea, vomiting, and weight loss. Distractor options will aggressively push you toward diagnosing an eating disorder or ordering a psychiatry consult. The correct first-line action is always to order a Beta-hCG to rule out pregnancy and a basic metabolic panel to assess for immediate electrolyte life threats.

8. THE BOARDROOM SCRIPT (OSCE & Oral Board Tips)

• The Opening Salvo: "Examiner, my immediate priority is assessing this patient's airway, breathing, and circulatory status. Given her history of an eating disorder and severe weight loss, I recognize her cardiac output may be profoundly reduced. I am ordering cautious, judicious IV fluid replacement rather than aggressive boluses to avoid precipitating heart failure."
• The Medical Rule-Out: "I am ordering a comprehensive metabolic panel to screen for hypokalemia and hypophosphatemia, a serum Beta-hCG to rule out pregnancy as a cause for her amenorrhea and vomiting, and an immediate 12-lead ECG to screen for a prolonged QTc, bradycardia, or ischemic changes suggesting ipecac toxicity."
• The Handoff: "With the patient medically stabilized, I am evaluating her using the SCOFF questionnaire to risk-stratify her eating disorder. Because she meets the strict admission criteria for physiologic instability with a heart rate of 42 bpm and a temperature of 35.2°C, and due to the high mortality rate associated with anorexia, I have placed her on suicide precautions. I am admitting her to a medical unit capable of telemetry monitoring and specialized refeeding protocols."