IBS Flashcards
What are the functional bowel disorders? What are some examples?
Symptoms referable to the GI
tract not explained by
structural or biochemical
abnormalities
- Irritable Bowel Syndrome
- Functional Dyspepsia
- Functional Constipation
- Functional Diarrhea
- Functional Heartburn
- Cyclic Vomiting Syndrome
How are the functional GI disorders related? When should alternate diagnoses be considered?
- Syndromes can overlap
- Over time, syndromes can change from one predominant
symptom complex to another
• Consider alternative diagnoses when symptoms change
significantly and/or warning symptoms develop
What are some hypotheses as to the pathophys of FGIDs?
Genetics
Psychosocial
Motor Disturbances
Visceral Hypersensitivity
Inflammation
Bacterial Flora
Brain-Gut Interaction
Describe how genetics relates to FGIDs.
Most work has been done in IBS and functional dyspepsia (FD)
• Family and twin studies
About 1⁄2 the liability for developing a FGID relates to genetic factors
- Serotonin metabolism
- Local mucosal immune function
- Cytokine levels
- Alteration of GI transit
- G-protein polymorphism
Early childhood experiences also influence the development of
FGIDs
How do psychosocial factors affect FGIDs?
- FGIDs are not psychosomatic disorders!
- Most have no greater psychosocial stressors
than controls
- Stress affects GI function
- Motor, sensory changes
- Individuals with higher degrees of
psychosocial stress have poorer outcomes
• FGIDs affect one’s ability to work, socialize,
and eat
Describe some altered motor responses and which FGIDs they are associated with.
A variety of altered motor responses have been described in
the FGIDs
- Rapid transit, increased contractions
- IBS-D, Functional diarrhea
- Slow transit, reduced contractions
- IBS-C, Functional constipation
- Altered accommodation response
- Functional dyspepsia
- Pronounced gastrocolic response
- IBS (diarrhea, cramps)
Describe how visceral hypersensitivity relates to FGIDs.
• Normal physiologic stimuli result in
exaggerated symptoms
• Reduced threshold to cause
symptoms
- Altered somatic referral patterns
- Modulated on multiple potential
areas
- ENS
- CNS
- Spinal pathways
- Autonomic responses
Describe how inflammation relates to FGIDs.
A preceding infectious illness predisposes
individuals to the development of a FGIDs
- Functional dyspepsia
- Irritable bowel syndrome
Mechanisms:
- Persistent mucosal inflammation
- Changes in cytokine expression
- Changes in secretion
- Up regulation of sensory pathways
- Psychosocial Stressors – (more likely if illness is
severe)
Which FGID do bacterial flora relate to?
Most referable to IBS
What is IBS? What is the ROME III definition?
It is chronic and episodic abdominal pain or discomfort
associated with altered bowel habit.
- Constipation
- Diarrhea
- Alternating
Recurrent abdominal pain or discomfort > 3 days per month in The past 3 months*
With 2 of 3 features:
Improved withdefecation
Onset associated with a change in stool frequency
Onset associated with a change in stool form
- Symptom onset at least 6 months before diagnosis
What are 4 categories of IBS? How are they differentiated?
- Diarrhea
- Constipation
- Mixed (alternating)
- Undifferentiated
Pattern is based on stool form
What is the epidemiology of IBS?
IBS prevalence: 10 – 20% in the US
More common in women than men
Onset from age 20s to mid-40s
Accounts for a third of visits to gastroenterologists and 12%
of visits to PCPs
Increased healthcare utilization
- Nearly twice as many abdominal surgeries
- IBS patients incur more healthcare costs
Reduced quality of life
How should a diagnosis of IBS be made?
Diagnosis is based on the presence of typical symptoms, an absence of red flags and exclusion of other common diseases with similar presentations. One strategy is as follows:
A. Document symptoms
B. Limited screen for organic disease if moderate to severe symptoms or warning symptoms
CBC
Erythrocyte sedimentation rate
Chemistry panel (including albumin, calcium, glucose, renal and hepatic)
TSH
Stool ova and parasite (diarrhea & bloating; also consider giardia antigen)
Colonoscopy if age of onset > 40 and colonoscopy if strong FH of colon cancer
Tissue transglutaminase or Endomysial Antibodies (Celiac is more common in individuals with IBS symptoms than in the general population).
Consider hydrogen breath testing (especially for bloaters)
*Identified abnormalities during screening require further investigation and treatment
C. Determine predominant symptom:
Constipation predominant
Diarrhea predominant
Mixed
Describe various steps and substeps for treating an IBS patient.
A. Develop an effective physician-patient relationship! (see below)
B. Review diet history for potential exacerbating patterns and recommend changes
e.g. modify lactose, fructose, fiber intake, fat intake etc.
C. Review medications and eliminate offending agents:
e.g. NSAIDs, narcotics, metformin
C. Provide education and reassurance
D. Begin a therapeutic trial based on main symptoms
- Increase dietary fiber (25 – 35 g per day) for constipation or add an osmotic laxative (e.g. polyethylene glycol 3350)
- Try an anti-diarrheal for diarrhea, e.g. loperamide 2 mg before meals
- Try an antispasmodic for cramps, bloating
- Amitiza for constipation and bloating
- Alosetron for moderate to severe diarrhea
- Low dose tricyclic antidepressants to modulate pain
- Consider antibiotic or probiotic therapy
What are some objective alterations in function that IBS patients have? What is another associated factor?
Abnormal motor function: small intestine and colon
Abnormal visceral perception
Patients with IBS are more sensitive to gut distension than normal.
Psychological distress
May be more an associated exacerbating factor than causation
• The role of post-infectious diarrhea is well established
