FCPS Paediatrics TOACS · Interactive Station EATING DISORDER

✅ Candidate's answer:
• Diagnosis: Bulimia nervosa (BN).
• DSM-5 criteria (all must be met):
1️⃣ Recurrent episodes of binge eating, characterized by: (a) eating a larger amount of food than most people would eat in a similar period under similar circumstances, and (b) a sense of lack of control over eating during the episode.
2️⃣ Recurrent inappropriate compensatory behaviors to prevent weight gain (e.g., self-induced vomiting, laxatives, diuretics, fasting, excessive exercise).
3️⃣ The binge eating and compensatory behaviors both occur, on average, at least once a week for 3 months.
4️⃣ Self-evaluation is unduly influenced by body shape and weight.
5️⃣ The disturbance does not occur exclusively during episodes of anorexia nervosa.
• Severity: Mild (1-3 compensatory episodes/week), Moderate (4-7), Severe (8-13), Extreme (14+).

✅ Candidate's answer:
• Anorexia nervosa (binge-purge subtype): Weight is significantly low (<85% expected body weight or BMI <18.5 for age). There is intense fear of gaining weight, and body image disturbance is prominent.
• Bulimia nervosa: Weight is typically within normal range or above. This patient’s BMI is 19.8 (45th percentile) – normal weight. If she lost significant weight, she might cross over to AN.
• Both conditions involve binge-purge behaviors, but BN does NOT require low weight. In fact, most BN patients have normal or slightly above-normal weight.
• If a patient meets criteria for both AN (low weight) and BN, the diagnosis is anorexia nervosa, binge-purge subtype – BN is not diagnosed concurrently.

✅ Candidate's answer:
• Russell sign: Calluses or scars on the dorsum of the hand (knuckles), typically over the metacarpophalangeal joints, caused by repeated self-induced vomiting (teeth scraping against the skin).
• Pathogenesis: The patient inserts fingers (often index and middle finger) into the pharynx to stimulate the gag reflex. The maxillary incisors abrade the dorsal skin of the hand.
• Significance: A pathognomonic physical sign of bulimia nervosa. It may also be seen in anorexia nervosa (binge-purge subtype).
• The patient in this case has calluses on her right hand – likely her dominant hand.

✅ Candidate's answer:
• Parotid (and submandibular) gland enlargement occurs in up to 50% of patients with bulimia nervosa.
• Pathophysiology: Chronic binge eating and self-induced vomiting → stimulation of salivary glands (increased sympathetic/parasympathetic tone) → hypertrophy and hyperplasia of glandular tissue → painless, bilateral parotid swelling.
• Differential diagnosis: Mumps, sialadenitis, Sjögren syndrome, sarcoidosis. In BN, it is usually bilateral, non-tender, and resolves with cessation of vomiting.
• Patients may complain of dry mouth (xerostomia) or sialadenosis.
• Can be confirmed with ultrasound (enlarged, echogenic glands).

✅ Candidate's answer:
• Perimolysis: Dental erosion caused by chronic exposure to gastric acid (pH 1.5-2.0) during self-induced vomiting.
• Characteristic findings:
- Loss of dental enamel on the lingual (palatal) surfaces of maxillary teeth (upper incisors, canines, premolars).
- Teeth become smooth, glassy, translucent, and shortened.
- Cupping or flattening of occlusal surfaces.
- Increased risk of dental caries, tooth fracture, and tooth loss.
• The mandibular teeth may be less affected because the tongue protects them.
• Advise patients to rinse with water or baking soda solution (not brush immediately) after vomiting to neutralize acid.

✅ Candidate's answer:
• Hypokalemia (low potassium) – loss of potassium in gastric fluid (gastric juice contains 5-10 mEq/L K+).
• Hypochloremia (low chloride) – loss of HCl (hydrochloric acid) from stomach.
• Metabolic alkalosis (high HCO3, high pH) – loss of gastric acid (H+) leads to net gain of bicarbonate.
• Hypovolemia – volume depletion due to fluid loss, leading to compensatory aldosterone secretion → worsening hypokalemia (aldosterone causes renal K+ wasting).
• Paradoxical aciduria – despite systemic alkalosis, urine pH is <5.5 because the kidney retains Na+ and excretes H+ in response to volume depletion (RAAS activation).
• Hyponatremia (less common) – from water intake or ADH secretion.
• Elevated serum amylase (salivary type) – due to parotid hypertrophy.

✅ Candidate's answer:
• Cardiac complications (usually from electrolyte disturbances):
- Hypokalemia → U waves, flattened T waves, ST depression, and increased risk of ventricular arrhythmias (e.g., premature ventricular contractions, ventricular tachycardia, torsade de pointes).
- QT interval prolongation (especially with hypokalemia, hypocalcemia, or hypomagnesemia).
- Sudden cardiac death – rare but reported in severe BN.
- Hypotension and orthostatic intolerance – due to hypovolemia.
- Bradycardia – if there is concomitant malnutrition (less common in BN than AN).
• Tests to order:
- ECG (electrocardiogram) – to assess QT interval, rhythm, and signs of hypokalemia.
- Serum electrolytes (K+, Na+, Cl-, Ca2+, Mg2+).
- Monitor for QT prolongation before starting SSRIs (some SSRIs can prolong QT).

✅ Candidate's answer:
• Esophageal complications:
- Mallory-Weiss tears (linear lacerations at the gastroesophageal junction) → hematemesis.
- Esophageal rupture (Boerhaave syndrome) – rare but life-threatening (chest pain, subcutaneous emphysema, pneumothorax).
- Gastroesophageal reflux disease (GERD) – worsened by repeated vomiting.
• Gastric complications:
- Gastric dilatation or rupture (rare, from binge eating).
- Delayed gastric emptying (gastroparesis).
• Laxative abuse complications: (if present) – cathartic colon, chronic diarrhea, fluid-electrolyte imbalance.
• Constipation – common in BN, may be due to low fiber, dehydration, or laxative withdrawal.

✅ Candidate's answer:
• First-line psychotherapy: Cognitive-Behavioral Therapy (CBT) – specifically CBT-BN or CBT-Enhanced (CBT-E).
• Key components (typically 16-20 sessions over 4-5 months):
1️⃣ Psychoeducation – educate about BN, the binge-purge cycle, and the medical consequences.
2️⃣ Self-monitoring – track eating behaviors, binge episodes, purging, and triggers.
3️⃣ Establish regular eating patterns – three meals and 1-2 snacks/day (no skipping meals).
4️⃣ Identify and challenge dysfunctional thoughts about body shape, weight, and eating.
5️⃣ Exposure to “forbidden” foods – to reduce avoidance and anxiety.
6️⃣ Relapse prevention – develop coping strategies for high-risk situations.
• CBT is more effective than medication alone – and is recommended as first-line treatment (alone or with SSRIs).

✅ Candidate's answer:
• First-line medication: Fluoxetine (Prozac) – a selective serotonin reuptake inhibitor (SSRI).
• Recommended dose for BN: 60 mg/day (higher than the dose for depression).
• Target: Reduction of binge-purge episodes. Response may take 4-6 weeks.
• Other SSRIs (sertraline, escitalopram) may be used off-label, but fluoxetine has the strongest evidence.
• Mechanism: Serotonin dysregulation is implicated in binge-purge behaviors; SSRIs reduce impulsivity and improve mood.
• Important: SSRIs are adjunctive to CBT, not a replacement. Combined treatment (CBT + fluoxetine) is more effective than either alone.
• Monitor for side effects: nausea, insomnia, sexual dysfunction, and risk of suicidal ideation (black box warning for all SSRIs in young adults).

✅ Candidate's answer:
• Complications of laxative abuse:
- Electrolyte disturbances: hypokalemia, hyponatremia, hypocalcemia, hypomagnesemia → metabolic alkalosis (vomiting) or metabolic acidosis (some laxatives).
- Dehydration and hypovolemia.
- Cathartic colon: loss of normal colonic motility, leading to chronic constipation (paradoxically).
- Melanosis coli (dark pigmentation of colonic mucosa from anthraquinone laxatives).
- Steatorrhea and malabsorption.
• Management of laxative abuse:
- Explain that laxatives do NOT cause weight loss – they only remove water and electrolytes (calories are absorbed in small intestine, laxatives act on colon).
- Gradual withdrawal (abrupt cessation may cause severe constipation and edema).
- Start a bowel regimen with fiber, stool softeners (docusate), and osmotic agents (polyethylene glycol).
- Educate and reassure that rebound edema is temporary.

✅ Candidate's answer:
• While Russell sign is highly suggestive of BN, other causes of knuckle calluses include:
- Occupational/recreational: Guitar playing, rock climbing, rowing, weightlifting, boxing.
- Knuckle pads (fibromas) – associated with Dupuytren contracture, Ledderhose disease.
- Chronic irritation/friction.
• However, in a young woman with normal weight, dental erosion, and parotid enlargement, the context strongly favors BN.
• The candidate should ask about the location, occupation, and handedness to differentiate.

✅ Candidate's answer:
• Laboratory tests:
- Complete blood count (CBC) – check for anemia (iron deficiency from poor diet).
- Comprehensive metabolic panel (CMP) – Na, K, Cl, CO2 (assess metabolic alkalosis), BUN, creatinine (renal function), glucose, calcium, magnesium, phosphorus, liver enzymes (may be elevated).
- Serum amylase and lipase – amylase (salivary) is often elevated in BN; lipase may be elevated if pancreatitis (rare).
- TSH, free T4 – to rule out thyroid disorders (weight changes).
- Pregnancy test – before starting any medication.
- Urinalysis – assess hydration status (specific gravity) and rule out laxative use (alkaline urine in vomiting).
• ECG:
- Assess for QTc prolongation (fluoxetine can cause QT prolongation; hypokalemia also causes QT prolongation).
- Normal QTc is <440 msec in males, <460 msec in females.
- Also look for U waves, flattened T waves, arrhythmias.
- If QTc >450-460 msec or if there are electrolyte abnormalities, correct electrolytes before starting SSRI.

✅ Candidate's structured answer:
• To the patient (privately first, if possible):
- “Thank you for being honest with me. What you are going through is very common, and it is not your fault. This is a medical condition called bulimia nervosa, not a lack of willpower.”
- “The cycle of binge eating and purging is driven by brain chemistry and stress. We have very effective treatments.”
- “I’m not here to judge you. I’m here to help you get better. We will work together.”
• To the mother (with patient):
- “Your daughter has bulimia nervosa. This is a serious eating disorder, but it is treatable. The behaviors she is engaging in (vomiting) are not a choice – they are a symptom of the illness.”
- “The physical signs we found (Russell sign, parotid swelling, dental erosion) confirm the diagnosis. We need to check her blood electrolytes and heart function because vomiting can cause dangerous low potassium levels.”
- “The most effective treatment is a type of therapy called cognitive-behavioral therapy (CBT), which teaches her to break the binge-purge cycle. Often we also use medication (fluoxetine) at a higher dose to reduce the urges.”
- “Nutritional rehabilitation – eating regular meals – is also critical. You can support her by not commenting on her weight, avoiding family meals that feel pressured, and encouraging her to see a therapist and dietitian.”
- “With treatment, most people recover fully. But untreated bulimia can lead to serious complications like heart problems, tooth loss, and even death.”
- “You are not alone. We will refer her to a therapist who specializes in eating disorders. Please encourage her, but do not blame her. This is a medical illness, not a character flaw.”