IBS

Question 1

What are the functional bowel disorders? What are some examples?

Answer 1

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

Question 2

How are the functional GI disorders related? When should alternate diagnoses be considered?

Answer 2

• 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

Question 3

What are some hypotheses as to the pathophys of FGIDs?

Answer 3

Genetics

Psychosocial

Motor Disturbances

Visceral Hypersensitivity

Inflammation

Bacterial Flora

Brain-Gut Interaction

Question 4

Describe how genetics relates to FGIDs.

Answer 4

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

Question 5

How do psychosocial factors affect FGIDs?

Answer 5

• 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

Question 6

Describe some altered motor responses and which FGIDs they are associated with.

Answer 6

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)

Question 7

Describe how visceral hypersensitivity relates to FGIDs.

Answer 7

• 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

Question 8

Describe how inflammation relates to FGIDs.

Answer 8

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)

Question 9

Which FGID do bacterial flora relate to?

Answer 9

Most referable to IBS

Question 10

What is IBS? What is the ROME III definition?

Answer 10

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

Question 11

What are 4 categories of IBS? How are they differentiated?

Answer 11

• Diarrhea
• Constipation
• Mixed (alternating)
• Undifferentiated

Pattern is based on stool form

Question 12

What is the epidemiology of IBS?

Answer 12

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

Question 13

How should a diagnosis of IBS be made?

Answer 13

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

Question 14

Describe various steps and substeps for treating an IBS patient.

Answer 14

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

1. Increase dietary fiber (25 – 35 g per day) for constipation or add an osmotic laxative (e.g. polyethylene glycol 3350)
2. Try an anti-diarrheal for diarrhea, e.g. loperamide 2 mg before meals
3. Try an antispasmodic for cramps, bloating
4. Amitiza for constipation and bloating
5. Alosetron for moderate to severe diarrhea
6. Low dose tricyclic antidepressants to modulate pain
7. Consider antibiotic or probiotic therapy

Question 15

What are some objective alterations in function that IBS patients have? What is another associated factor?

Answer 15

 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