350.3 🏥 內科專科考前版

350.3.1 Mechanistic Deep Dive

350.3.1.1 Visceral Hypersensitivity

  • Reduced threshold for pain
  • Central + peripheral sensitization
  • Cortical processing differences (fMRI studies)

350.3.1.2 Brain-Gut Axis

  • Vagal afferents
  • Cortical-subcortical interactions
  • HPA axis
  • Microbiome influence

350.3.1.3 Microbiome in IBS

  • Reduced diversity
  • Specific patterns
  • Probiotic vs antibiotic (rifaximin) effects

350.3.2 Recent Trials & Updates

350.3.2.1 Tenapanor (Ibsrela) for IBS-C

  • NHE3 inhibitor
  • Reduces small bowel Na absorption
  • ↑ Intestinal fluid
  • FDA 2019 (IBS-C); 2021 (hyperphosphatemia)

350.3.2.2 Plecanatide for IBS-C

  • Similar to linaclotide
  • FDA 2017

350.3.2.3 Rifaximin for IBS-D

  • Non-absorbed antibiotic
  • 14-day course
  • Re-treatment possible if relapse
  • FDA 2015

350.3.2.4 Eluxadoline

  • Mu-opioid agonist + delta antagonist
  • Restricted use (avoid pancreatitis, cholecystectomy)

350.3.2.5 FMT (Fecal Microbiota Transplant) for IBS

  • Multiple trials mixed results
  • Maybe specific subtypes benefit
  • Investigational

350.3.2.6 Gut-Directed Hypnotherapy

  • Manchester model
  • ↑ Evidence
  • Multidisciplinary clinics

350.3.3 High-Yield Specialist Points

350.3.3.1 Low FODMAP Diet

  • 3 phases: restriction → reintroduction → personalization
  • Dietitian guidance ideal
  • Not lifelong (restriction)

350.3.3.2 Probiotics in IBS

  • Specific strains may help (Bifidobacterium infantis 35624)
  • VSL#3 for IBS-D
  • Limited evidence overall

350.3.3.3 Rifaximin Re-Treatment

  • TARGET-3 study: re-treatment effective
  • 14-day course
  • Up to 3 courses studied

350.3.3.4 Anti-Diarrheal Considerations

  • Loperamide: peripheral mu-opioid; safe
  • Eluxadoline: be careful with pancreatitis, cholecystectomy history (Viberzi REMS)
  • Alosetron: ischemic colitis risk; REMS program (women only)

350.3.3.5 IBS Subtypes + Mental Health

  • High comorbidity with anxiety, depression
  • Treat both
  • CBT effective

350.3.3.6 IBS in Pregnancy

  • Symptoms may improve or worsen
  • Safe options: dietary, antispasmodics, low-dose TCA
  • Avoid: alosetron, prucalopride, lubiprostone

350.3.3.7 IBS Refractory Cases

  • Multidisciplinary
  • Combination therapies
  • Specialist referral
  • Trials of newer agents

350.3.3.8 Pelvic Floor Dyssynergia

  • Anorectal manometry + balloon expulsion
  • Treatment: biofeedback (effective)

350.3.3.9 Slow Transit Constipation

  • Sitz marker study
  • Treatment: prucalopride, lubiprostone, linaclotide
  • Surgery rarely (colectomy + IRA for severe)

350.3.3.10 IBS-Like Conditions to Differentiate

  • IBD (calprotectin)
  • Celiac
  • Microscopic colitis
  • SIBO
  • Bile acid diarrhea
  • Endocrine (hyperthyroid, DM)
  • Chronic infection

350.3.3.11 Psychological + IBS

  • CBT > placebo
  • Gut-directed hypnotherapy effective
  • Mindfulness, acceptance + commitment therapy

350.3.3.12 Childhood IBS

  • Different presentation
  • Less medication evidence
  • Diet + behavioral focus

350.3.4 Pearls

  • IBS Rome IV: pain + 2 of (defecation, frequency, form)
  • Alarm features → colonoscopy + workup
  • Fecal calprotectin distinguishes IBD from IBS
  • Low FODMAP: most evidence dietary
  • IBS-C: linaclotide, lubiprostone, plecanatide, tenapanor, prucalopride
  • IBS-D: rifaximin, eluxadoline, alosetron, loperamide, bile acid sequestrants
  • TCAs for IBS-D pain; SSRIs for IBS-C
  • CBT strongest psychological therapy evidence
  • CHS: heavy cannabis + hot shower relief; cessation cure