Subjective: Chief Complaint (CC): Abdominal pain and bloating. HPI: H.M. is a 28-year-old Caucasian female who presents with complaints of intermittent abdominal pain and bloating for the past six months. Her mother reports observing unusual eating patterns since H.M. moved back home three months ago after a breakup. H.M. attributes her recent weight gain to her job as a catering manager, where she is constantly exposed to food. Six months ago, H.M. began vomiting after eating large meals to prevent weight gain, which she continues to do at least three times a week. She also exercises rigorously, attending yoga and exercise classes six times a week. Despite being on a low-calorie diet, H.M. reports a loss of control over her eating habits and feels bad when she overeats. PMHx: H.M. has no significant past medical history reported. Demographics: 28-year-old Caucasian female. PSHx: None reported. Allergies: None reported. Lifestyle: H.M. works as a catering manager at a resort hotel. She exercises rigorously, participating in yoga and exercise classes six times a week. She has a history of self-induced vomiting to control weight. Objective:

• General: H.M. appears well-nourished but has a history of recent significant weight gain.
• Abdomen: Soft, non-distended, with mild tenderness on palpation. No rebound tenderness or guarding. Bowel sounds are normal.
• Skin: No rashes or lesions.
• Psychiatric: H.M. appears anxious when discussing her eating habits and weight gain.

Assessment: Primary Diagnosis:

1. Bulimia Nervosa (ICD-10: F50.2)
   • Pathophysiology: Bulimia nervosa is an eating disorder characterized by recurrent episodes of binge eating followed by compensatory behaviors such as self-induced vomiting, fasting, excessive exercise, or misuse of laxatives. The disorder is associated with psychological distress and a preoccupation with body weight and shape.
   • Rationale: H.M. exhibits key symptoms of bulimia nervosa, including binge eating, self-induced vomiting, and excessive exercise. Her reported feelings of loss of control and guilt after eating further support this diagnosis.

Differential Diagnoses:

1. Gastroesophageal Reflux Disease (GERD) (ICD-10: K21.9)
   • Pathophysiology: GERD occurs when stomach acid frequently flows back into the tube connecting the mouth and stomach (esophagus). This backwash (acid reflux) can irritate the lining of the esophagus, leading to symptoms such as heartburn, regurgitation, and abdominal pain.
   • Rationale: H.M.’s symptoms of abdominal pain and bloating could also be related to GERD, especially considering her history of vomiting, which can aggravate or cause GERD.
2. Irritable Bowel Syndrome (IBS) (ICD-10: K58.9)
   • Pathophysiology: IBS is a common disorder that affects the large intestine, causing symptoms like cramping, abdominal pain, bloating, gas, and diarrhea or constipation. The exact cause of IBS is unknown, but it is believed to involve a combination of gut-brain interaction, altered gut motility, and increased sensitivity to pain.
   • Rationale: The chronic nature of H.M.’s abdominal pain and bloating could be indicative of IBS, particularly if stress and dietary factors exacerbate her symptoms.

Comparison of Differential Diagnoses:

• Occurrence:
  • Bulimia Nervosa is more common in young females and often occurs in those with a history of body image issues and dieting.
  • GERD can occur in individuals of all ages but is particularly prevalent in those with a history of obesity, poor diet, or frequent vomiting.
  • IBS is a functional gastrointestinal disorder that affects about 10-15% of the adult population worldwide, with a higher prevalence in women.
• Pathophysiology:
  • Bulimia Nervosa involves psychological and behavioral components leading to physical symptoms like abdominal pain due to repeated vomiting.
  • GERD is a result of acid reflux damaging the esophageal lining.
  • IBS involves a complex interaction between the nervous system and the gastrointestinal tract, leading to altered bowel habits and abdominal pain.
• Presentation:
  • Bulimia Nervosa presents with signs of repeated bingeing and purging, alongside psychological distress and concerns about weight.
  • GERD typically presents with heartburn, acid regurgitation, and sometimes abdominal pain, which may worsen after eating or lying down.
  • IBS presents with chronic abdominal pain, bloating, and changes in bowel habits, often exacerbated by stress or specific foods.

Diagnostic Testing:

1. Bulimia Nervosa:
   • Psychiatric Evaluation: To assess the presence of eating disorders and associated psychological issues.
   • Electrolyte Panel: To check for imbalances due to frequent vomiting.
   • Esophagogastroduodenoscopy (EGD): To evaluate any damage to the esophagus or stomach lining caused by repeated vomiting.
2. GERD:
   • Upper Endoscopy: To visualize the esophagus and stomach and assess for damage caused by acid reflux.
   • 24-hour pH Monitoring: To measure acid levels in the esophagus and confirm GERD.
3. IBS:
   • Stool Studies: To rule out infections or inflammatory conditions.
   • Colonoscopy: To rule out other causes of chronic abdominal pain and assess for IBS-related changes.

National Guidelines:

• Bulimia Nervosa: The American Psychiatric Association (APA) recommends a comprehensive evaluation for eating disorders, including psychological assessment and monitoring of medical complications such as electrolyte imbalances.
• GERD: The American College of Gastroenterology (ACG) recommends an empirical trial of proton pump inhibitors (PPIs) for symptomatic relief and upper endoscopy for patients with alarm symptoms or chronic GERD.
• IBS: The American College of Gastroenterology (ACG) guidelines suggest a symptom-based approach to diagnosis, with testing directed by clinical presentation, and recommend dietary modifications and psychosocial therapy as initial treatment strategies.