What is the initial management for a suspected eating disorder in a patient with low BMI, tachycardia, hypotension, and dental erosions?

Initial Management of Suspected Eating Disorder with Purging Behaviors

This 15-year-old girl with dental erosions (indicating purging behavior), borderline low blood pressure, and low-normal BMI requires immediate comprehensive assessment including vital signs with orthostatic measurements, complete blood count, comprehensive metabolic panel with electrolytes, and an electrocardiogram, followed by initiation of family-based treatment as the first-line psychotherapy. 1, 2, 3

Immediate Clinical Assessment

Vital Signs and Physical Examination

• Measure orthostatic vital signs immediately – check blood pressure and heart rate both supine and standing, as orthostatic hypotension and tachycardia indicate hemodynamic instability requiring urgent intervention 1, 2, 3
• Document current weight, height, and calculate BMI percentile for age (her BMI of 18 may be low for a 15-year-old depending on growth trajectory) 1, 2
• Examine for additional purging signs beyond dental erosions – look for Russell's sign (calluses on knuckles from self-induced vomiting), parotid gland enlargement, and oral/pharyngeal trauma 2, 4
• Assess temperature, as hypothermia can occur with malnutrition 1, 2

Urgent Laboratory Testing

• Order comprehensive metabolic panel immediately to detect hypokalemia, hypochloremia, hyponatremia, and metabolic alkalosis from purging, which can cause fatal cardiac arrhythmias 1, 2
• Obtain complete blood count to identify anemia and leukopenia from malnutrition 1, 2, 3
• Check liver enzymes and renal function (BUN, creatinine) as part of metabolic panel 1, 2

Cardiac Evaluation

• Obtain electrocardiogram urgently – patients with purging behaviors are at high risk for QTc prolongation and sudden cardiac death from electrolyte abnormalities 1, 2, 3
• Monitor QTc intervals closely, as this population requires ongoing cardiac surveillance 1, 2

Critical pitfall to avoid: Normal laboratory values do NOT exclude serious illness – approximately 60% of anorexia nervosa patients show normal routine labs despite severe malnutrition 2. Do not be falsely reassured by normal results.

Diagnostic Clarification

Detailed Behavioral Assessment

• Quantify purging frequency and methods (self-induced vomiting, laxative use, diuretic use) over the past week and month 1
• Document restrictive eating patterns, binge eating episodes, and compensatory exercise behaviors 1
• Assess weight history including maximum, minimum, and recent changes 1
• Evaluate percentage of time preoccupied with food, weight, and body shape 1
• Screen for co-occurring psychiatric conditions, particularly depression and suicidality (25% of anorexia nervosa deaths are from suicide) 2, 3, 5

The dental erosions strongly suggest bulimia nervosa or purging-type anorexia nervosa – this finding indicates chronic acid exposure from recurrent vomiting 4, 6, 7

Treatment Initiation

First-Line Psychotherapy

• Immediately refer for family-based treatment (FBT) – this is the first-line evidence-based treatment for adolescents with eating disorders, with remission rates of 48.6% at 6-12 months versus 34.3% with individual treatment (OR 2.08,95% CI 1.07-4.03) 1, 2, 3, 5
• FBT involves parental supervision of eating and caregiver education to normalize eating behaviors and restore weight 1, 3
• Central family involvement is essential for therapeutic success in this age group 3

Multidisciplinary Team Assembly

• Establish coordinated care team immediately including medical provider, psychiatrist, psychologist/therapist trained in eating disorders, and registered dietitian 1, 2, 3
• Create documented, comprehensive, person-centered treatment plan 1

Pharmacotherapy Considerations

• If bulimia nervosa is confirmed, add fluoxetine 60 mg daily either initially or if minimal response to psychotherapy alone by 6 weeks 1, 8, 5
• Fluoxetine decreases binge/purge episodes even in patients without depression (standardized mean difference -0.24, small effect size) 5

Hospitalization Criteria

Admit to acute care hospital if any of the following are present:

• Severe bradycardia (heart rate <50 bpm in adolescents) 2, 3
• Severe hypotension or orthostatic instability 2, 3
• Significant electrolyte abnormalities (particularly hypokalemia) 2, 3
• QTc prolongation on ECG 2, 3
• Suicidal ideation or intent 2, 3
• Severe malnutrition requiring refeeding (initiate slowly with phosphorus supplementation to prevent fatal refeeding syndrome) 2, 3

Critical pitfall: Do not delay hospitalization based on patient or family denial of illness severity – eating disorders are life-threatening conditions requiring aggressive early intervention 2

Ongoing Monitoring

• Weigh patient at each visit using standardized protocol (same scale, same time of day, after voiding, in gown) 3
• Monitor vital signs including orthostatics at every visit 1, 2, 3
• Repeat electrolytes weekly initially if purging continues 2
• Continue cardiac monitoring with repeat ECGs as clinically indicated 1, 2