347.3 🏥 內科專科考前版

347.3.1 Mechanistic Deep Dive

347.3.1.1 Visceral Pain Pathways

  • Splanchnic nerves
  • Convergence with somatic afferents → referred pain
  • A-delta + C fibers

347.3.1.2 CTZ + Vomiting Center

  • Area postrema (outside BBB)
  • Inputs: vestibular, GI vagal, cortical
  • Antagonists: 5-HT3, dopamine, NK1, muscarinic

347.3.2 Recent Trials & Updates

347.3.2.1 Prucalopride for Chronic Constipation

  • 5-HT4 agonist
  • Long-term studies

347.3.2.2 Plecanatide, Linaclotide for IBS-C

  • Guanylate cyclase C agonists

347.3.2.3 Tenapanor for IBS-C

  • NHE3 inhibitor

347.3.2.4 Pyrazinamide-Containing Regimens

  • Beyond TB (other inflammatory)

347.3.3 High-Yield Specialist Points

347.3.3.1 Mesenteric Ischemia

  • Acute: arterial embolism > thrombosis > venous
  • Chronic: postprandial pain (“intestinal angina”)
  • CT angiography
  • Surgery / endovascular
  • Heparin acute

347.3.3.2 Acute Mesenteric Ischemia

  • Pain out of proportion
  • Elderly with AF (embolic)
  • Lactate elevated
  • CT angio
  • Emergent surgery often

347.3.3.3 Endoscopy Practical

  • Sedation considerations
  • Anticoagulation management
  • ASGE guidelines

347.3.3.4 Capsule Endoscopy Considerations

  • Small bowel evaluation
  • Contraindications: known stenosis, obstruction
  • Retention risk

347.3.3.5 ICP-Vomiting Triad

  • Severe headache + projectile vomiting + papilledema
  • Imaging

347.3.3.6 Bilirubin Metabolism

  • Heme → biliverdin → bilirubin (unconjugated)
  • Liver conjugation (UGT)
  • Biliary excretion
  • Enterohepatic recirculation

347.3.3.7 Hepatocellular vs Cholestatic LFT Pattern

  • AST/ALT > 5x with mild ALP: hepatocellular
  • ALP > 3x ULN + GGT: cholestatic
  • Bilirubin variable

347.3.3.8 Lactose Intolerance Testing

  • Hydrogen breath test
  • Lactose tolerance test
  • Lactase genetic testing

347.3.3.9 SIBO (Small Intestinal Bacterial Overgrowth)

  • Small bowel bacterial overgrowth
  • Bloating, diarrhea, malabsorption
  • Hydrogen + methane breath test
  • Treatment: antibiotics (rifaximin)

347.3.3.10 Pancreatic Insufficiency Testing

  • Fecal elastase < 200 ÎŒg/g
  • Pancreatic enzyme replacement (PERT)

347.3.3.11 Celiac Workup

  • Anti-tTG IgA (preferred screen)
  • Total IgA (rule out deficiency)
  • Anti-DGP IgG (if IgA deficient)
  • EGD with duodenal biopsy

347.3.3.12 Helicobacter Testing

  • Urea breath test (sensitive, non-invasive)
  • Stool antigen (sensitive)
  • Histology (gold standard with biopsy)
  • Serology (less specific; doesn’t distinguish current)
  • CLO test on biopsy

347.3.3.13 IBD Markers

  • Fecal calprotectin (sensitive for inflammation)
  • ANCA + ASCA (some)
  • CRP, ESR
  • Colonoscopy + biopsy gold standard

347.3.3.14 Constipation Subtypes

  • Normal transit
  • Slow transit (colonic inertia)
  • Outlet dysfunction (anorectal manometry)

347.3.3.15 Encopresis vs Constipation

  • Pediatric mostly
  • Stool impaction + overflow incontinence

347.3.3.16 COVID-19 + GI

  • Diarrhea, anorexia, nausea
  • Anosmia/ageusia
  • LFT abnormalities
  • GI inflammation

347.3.4 Pearls

  • Visceral pain: poorly localized, midline
  • Parietal pain: sharp, localized, peritonitis
  • Referred pain: shared embryology
  • Dysphagia workup: oropharyngeal vs esophageal; modified barium or EGD
  • Functional GI: Rome IV criteria
  • Alarm features in dyspepsia: ≥ 60 yo, weight loss, bleeding, dysphagia → EGD
  • Stool calprotectin distinguishes IBD vs IBS
  • Acute mesenteric ischemia: pain out of proportion + AF + lactate ↑
  • Jaundice workup: LFT + US first