Irritable Bowel Syndrome

Kathryn Welp

Background

  • Diagnose by the Rome IV criteria, no longer a diagnosis of exclusion
    • Recurrent abdominal pain on average at least 1 day/week in the last 3 months with an onset at least 6 months prior, associated with two or more of the following criteria
      • Pain related to defecation
      • Change in frequency of stool
      • Change in form (appearance) of stool
    • Patient has none of the following warning signs: >50yrs, evidence of GIB, nocturnal pain or BMs, unintentional weight loss, family hx of colorectal cancer or IBD, palpable abdominal mass or LAD, IDA, +FOBT
    • Classified based on predominant bowel habits
      • Diarrhea: >25% BMs with Bristol stool types 6 or 7
      • Constipation: >25% BMs with Bristol stool types 1 or 2
      • Mixed: both of above

Evaluation

  • Thorough H&P for alarm symptoms as above
  • Consider limited testing with CBC, CMP, CRP, celiac serology (TTG, anti-gliadin, etc), fecal calprotectin

Management 

  1. Lifestyle/Dietary Modifications:
    • Increased physical activity, low FODMAP diet (I: Eliminate high FODMAP foods for 4-6 wks, II: Incorporate foods back into diet and see what’s tolerable)
    • No evidence for probiotics (can potentially worsen bloating 2/2 SIBO)
  2. Psychosocial Treatment:
    • CBT, psychotherapy, therapeutic physician-patient relationship
  3. Pharmacologic Treatment:
    • Pain: colicky abdominal pain, avoid opioids
      • Peppermint oil (smooth muscle relaxant) – IBGuard, Iberogast
      • Antispasmodics: Hyosciamine acts faster than Dicyclomine
      • TCAs (slow GI transit): Amitriptyline or nortriptyline (causes less constipation so better in IBS-C)
    • Diarrhea:
      • Ondansetron (8mg TID), Loperamide (up to 16g qd), Rifaximin (550mg BID for 2 wks), Eluxadoline (75-100mg BID); consider Lomotil if refractory
    • Constipation:
      • Fiber (Ispaghula husk orange), Miralax, Linzess (first line but can be expensive), Trulance, or Amitiza
    • Other:
      • SSRIs, SNRIs for concomitant mood disorders
      • Gabapentin, Lyrica
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