Irritable Bowel Syndrome - Chapter 327 Flashcards
Definition of IBS
Irritable bowel syndrome (IBS) is
* a functional bowel disorder
* characterized by abdominal pain or discomfort and altered bowel habits
* in the absence of detectable structural abnormalities.
How to diagnose IBS
based on clinical presentation
IBS is a disorder that affects all ages, although most patients have their first symptoms before what age
before age 45
________ is a key symptom for the diagnosis of IBS.
pain is a key symptom for the diagnosis of IBS.
3 differenes of Rome IV criteria from Rome III
prerequisite clinical feature of IBS
vs
most consistent clinical feature in IBS
- abdominal pain – prerequisite clinical feature of IBS
- altered bowel habis – most consistent clinical feature in IBS
in IBS, abnormalities in the small bowel occur during the night
True or False
False….
abnormalities in the small bowel during the diurnal (waking) period; nocturnal motor patterns are not different from those of healthy controls.
colonic motor abnormalities are more prominent under unstimulated conditions in IBS.
True or False
FALSE…
* Studies of colonic myoelectrical and motor activity under unstimulated conditions have not shown consistent abnormalities in IBS.
* In contrast, colonic motor abnormalities are more prominent under stimulated conditions in IBS.
Inflation of rectal balloons BOTH in IBS-D and IBS-C patients leads to marked and prolonged distention-evoked contractile activity.
True or False
True
prolonged fasting in IBS patients is often associated with significant WORSENING of symptoms.
- IBS patients frequently exhibit exaggerated sensory responses to visceral stimulation.
- On the other hand, prolonged fasting in IBS patients is often associated with significant improvement in symptoms.
Lipids RAISE the thresholds for the first sensation of gas, discomfort, and pain in IBS patients.
True or False
Lipids lower the thresholds for the first sensation of gas, discomfort, and pain in IBS patients.
Apart from enhanced gut sensitivity, IBS patients also exhibit heightened sensitivity at what part of the body
In contrast to enhanced gut sensitivity, IBS patients do not exhibit heightened sensitivity elsewhere in the body
Functional brain imaging studies such as magnetic resonance imaging (MRI) have shown that in response to distal colonic stimulation THIS PART OF THE BRAIN shows greater activation in IBS patients.
Functional brain imaging studies such as magnetic resonance imaging (MRI) have shown that in response to distal colonic stimulation, the mid-cingulate cortex—a brain region concerned with attention processes and response selection—shows greater activation in IBS patients.
In addition to mid cingulate cortex, IBS patients also show preferential activation of the THIS PART OF BRAIN, which contains a vigilance network within the brain that increases alertness.
prefrontal lobe
Abnormal psychiatric features are recorded in up to 80% of IBS patients, especially in referral centers…. WHAT psychiatric diagnosis predominates.
Abnormal psychiatric features are recorded in up to 80% of IBS patients, especially in referral centers; however, no single psychiatric diagnosis predominates
Brain functional MRI studies show greater activation of the WHAT PART OF THE BRAIN of IBS patients with a past history of sexual abuse.
Brain functional MRI studies show greater activation of the posterior and middle dorsal cingulate cortex, which is implicated in affect processing in IBS patients with a past history of sexual abuse.
“postinfective” IBS occurs more commonly in males
True or False
“postinfective” IBS occurs more commonly
* in females
* and affects younger rather than older patients
“postinfective” IBS occurs more commonly in older people
True or False
“postinfective” IBS occurs more commonly
* in females
* and affects younger rather than older patients
Age older than ____years might protect against postinfectious IBS,
Age older than 60 years might protect against postinfectious IBS,
treatment with antibiotics has been associated with increased risk of postinfectious IBS
True or False
True
The microbes involved in the initial infection leading to postinfectious GBS are (3)
The microbes involved in the initial infection are
* Campylobacter
* Salmonella
* Shigella
Increased rectal mucosal enteroendocrine cells, T lymphocytes, and gut permeability are acute changes following THIS GUT INFECTION that could persist for more than a year and may contribute to postinfective IBS.
Increased rectal mucosal enteroendocrine cells, T lymphocytes, and gut permeability are acute changes following Campylobacter enteritis that could persist for more than a year and may contribute to postinfective IBS.
This cation channel play a central role to the initiation and persistence of visceral hypersensitivity.
cation channels such as TRPV1 (vanilloid) channels are central to the initiation and persistence of visceral hypersensitivity.
These cells have a prominent role in the pathogenesis of visceral hypersensitivity.
Mast cells
A high prevalence of small-intestinal bacterial overgrowth in IBS patients has been noted based on WHAT TEST
A high prevalence of small-intestinal bacterial overgrowth in IBS patients has been noted based on positive lactulose hydrogen breath test.
A high prevalence of small-intestinal bacterial overgrowth in IBS patients has been noted based on positive lactulose hydrogen breath test.
HOWEVER, Abnormal H2 breath test can occur because of ________ and may lead to erroneous interpretation
Abnormal H 2 breath test can occur because of small-bowel rapid transit and may lead to erroneous interpretation
IBS patients generally had decreased proportions of these bacteria
(2)
IBS patients generally had increased proportions of these bacteria
(3)
These bacteria are anti-inflammatory organisms (2) and may reduce mucosal inflammation in IBS patients
- Bifidobacterium
- Faecalibacterium
Bacteria capable of injuring epithelium lining and inducing mucosal inflammation via a lipopolysaccharide-dependent pathway
Bacteria that can produce toxin to dissolve glycoproteins and induce mucosal inflammation
Bacteria that can produce gas and organic acids from glucose and fructose fermentation, resulting in bloating and abdominal pain.
The serotonin-containing enterochromaffin cells in the colon are increased in a subset of IBS-C patients
True or False
False….
The serotonin-containing enterochromaffin cells in the colon are increased in a subset of IBS-D patients
WHAT is the rate-limiting enzyme in enterochromaffin cell serotonin biosynthesis
Tryptophan hydroxylase 1 (TPH1) is the rate-limiting enzyme in enterochromaffin cell serotonin biosynthesis
Effect of gut microbes on colonic serotonin production
gut microbes promote colonic serotonin production through an effect of short-chain fatty acids on enterochromaffin cells.
In IBS patients, the expression of THIS TRANSPORTER is downregulated due to gram negative gut dysbiosis.
In IBS patients, the expression of mucosal serotonin reuptake transporter (SERT) is downregulated due to gram negative gut dysbiosis.
4 clinical features that argue against the diagnosis of IBS
Postprandial pain accompanied by bloating, nausea, and vomiting suggests what 2 diseases
- gastroparesis
- or partial intestinal obstruction
this possibility should be ruled out before making a diagnosis of IBS
Patients with small intestinal bacteria overgrowth can present with abdominal pain, nausea, and bloating, and this possibility should be ruled out before making a diagnosis of IBS.
These 2 conditions are DDx for IBS-C. They can present with painful constipation as the major complaint
- Acute intermittent porphyria
- Lead poisoning
In patients with persistent diarrhea not responding to simple antidiarrheal agents, a sigmoid colon biopsy should be performed to rule out what disease….
In patients with persistent diarrhea not responding to simple antidiarrheal agents, a sigmoid colon biopsy should be performed to rule out microscopic colitis.
the possibility of lactase deficiency should be ruled out HOW (2)
the possibility of lactase deficiency should be ruled out with
* a hydrogen breath test
* or with evaluation after a 3-week lactose-free diet
Excessive gas with bloating also raises the possibility of small-bowel bacteria overgrowth and should be
ruled out with WHAT TEST
Excessive gas with bloating also raises the possibility of small-bowel bacteria overgrowth and should be
ruled out with a glucose hydrogen breath test
In patients with IBS with concurrent symptoms of dyspepsia, the ff tests are advisable (2)
- upper GI radiographs or
- esophagogastroduodenoscopy
In IBS patients with postprandial right upper quadrant pain, this imaging should be obtained.
In patients with postprandial right upper quadrant pain, an ultrasonogram of the gallbladder should be obtained.
Laboratory features that argue against IBS (4)
Laboratory features that argue against IBS include
* evidence of anemia,
* presence of leukocytes or blood in stool,
* elevated sedimentation rate,
* and stool volume >200–300 mL/d.
FODMAP stands for…
fermentable oligosaccharides, disaccharides, monosaccharides, and polyols
Stool-bulking agents bind water and thus prevent both excessive hydration and dehydration of stool.
True or False
True
This fiber has been shown to reduce perception of rectal distention
Psyllium
Which type of fiber tend to produce less bloating and distention.
Insoluble or soluble
Compared to insoluble dietary fiber such as wheat bran, soluble fibers such as psyllium preparations tend to produce less bloating and distention.
Target dose of total dietary and supplementary fiber per day
targeted dose of 20–30 g of total dietary and supplementary fiber per day.
These 2 kinds of constipation do not respond to fiber supplementation
- drug-induced constipation
- slow colonic transit constipation
Best timing to give antispamsmodics in order to prevent or control postprandial pain
Physiologic studies demonstrate that anticholinergic drugs inhibit the gastrocolic reflex; hence, postprandial pain is best managed by giving antispasmodics 30 min before meals so that effective blood levels are achieved shortly before the anticipated onset of pain.
Most anticholinergics contain ____, which may cause xerostomia, urinary hesitancy and retention, blurred vision, and drowsiness.
Most anticholinergics contain natural belladonna alkaloids, which may cause xerostomia, urinary hesitancy and retention, blurred vision, and drowsiness.
Example of synthetic anticholinergics causing less effect on mucous membrane secretion and produce fewer undesirable side effects
Dicyclomine
Peppermint oil appears to reduce abdominal cramps by WHAT mechanism.
Peppermint oil appears to reduce abdominal cramps by some undefined mechanism.
The most commonly reported adverse event with the use of peppermint oil is …..
Heartburn
initial therapy of choice for IBS-D
Peripherally acting opiate-based agents
Usual dose of loperamide
vs
Max dose per day
Why is increasing the dose of opiates not required to maintain antidiarrheal potency
In general, the intestines do not become tolerant of the antidiarrheal effect of opiates, and increasing doses are not required to maintain antidiarrheal potency.
Why can cholestyramine resin be useful sometimes in diarrhea in IBS
up to 30% of IBS-D patients may have bile acid malabsorption.
cholestyramine is a bile acid binder
This tricyclic antidepressant slows jejunal migrating motor complex transit propagation and delays orocecal and whole-gut transit
imipramine
Tricyclic antidepressants are useful in both IBS-D and IBS-C patients
True or False
False.
The beneficial effects of the tricyclic compounds in the treatment of IBS appear to be dependent of their effects on depression.
True or False
FALSE…
The beneficial effects of the tricyclic compounds in the treatment of IBS appear to be independent of their effects on depression.
In contrast to tricyclic agents, THIS DRUG accelerates orocecal transit, raising the possibility that this drug class may be useful in IBS-C patients
In contrast to tricyclic agents, the selective serotonin reuptake inhibitor (SSRI) paroxetine accelerates orocecal transit, raising the possibility that this drug class may be useful in IBS-C patients
tricyclic antidepressant imipramine kasi slows jejunal migrating motor complex transit propagation and delays orocecal and whole-gut transit… TCAs known to be effective in IBS-D talaga
This antidepressant blunts perception of rectal distention and reduces the magnitude of the gastrocolonic response in healthy volunteers.
The SSRI citalopram blunts perception of rectal distention and reduces the magnitude of the gastrocolonic response in healthy volunteers.
____, an over-the-counter oral β-glycosidase solution, may reduce rectal passage of gas without decreasing bloating and pain.
Beano, an over-the-counter oral β-glycosidase solution, may reduce rectal passage of gas without decreasing bloating and pain.
____ reduce bloating, gas, and fullness during and after high-calorie, high-fat meal ingestion.
Pancreatic enzymes reduce bloating, gas, and fullness during and after high-calorie, high-fat meal ingestion.
These serotonin receptors (2) are found throughout the GI tract.
Serotonin 5-HT 3 and 5-HT 4 receptors are found throughout the GI tract.
____, a dihydrobenzo-furancarboxamide derivative, is a new selective agonist of 5-HT4 .
Prucalopride, a dihydrobenzo-furancarboxamide derivative, is a new selective agonist of 5-HT4 . Used for constipation. Parang Tegaserod
Advantage of Prucalopride from Tegaserod
Prucalopride was approved by the European Medicines Agency and the U.S. Food and Drug Administration (FDA) for treatment of ……
chronic constipation
In 2007, this 5-HT4 receptor agonist was voluntarily withdrawn from the market after a greater number of cardiovascular complications
Tegaserod
____ is the only major side effect of Tegaserod
Tegaserod a 5-HT4 receptor agonist
Diarrhea
Tegaserod was withdrawn initially from the market but in 2019 the FDA approved the use of tegaserod in women provided they meet these 3 conditioons
secretagogues that stimulate net efflux of ions and water into the intestinal lumen and thus enhance transit and facilitate ease of defecation (3)
Lubiprostone, linaclotide, and plecanatide are secretagogues that stimulate net efflux of ions and water into the intestinal lumen and thus enhance transit and facilitate ease of defecation.
Secretagogues increase intestinal secretion of this electrolyte
Secretagogues increase intestinal chloride secretion
This secretatgogue is a bicyclic fatty acid derived from prostaglandin E 1 that activates type 3 chloride channels in the apical membrane of intestinal epithelial cells.
These secretagogouges are minimally absorbed 14-amino-acid peptide guanylate cyclase-C (GC-C) agonists that bind to and activate GC-C on the luminal surface of intestinal epithelium. (2)
Oral lubiprostone was effective in the treatment of patients with IBS-D
True or False
False….
Oral lubiprostone was effective in the treatment of patients with IBS-C
recommended daily dose of lubiprostone
Lubiprostone recommended daily dose is 24 mg twice daily
major side effects of lubiprostone (2)
nausea and diarrhea
These drugs are similar to endogenous peptides secreted by the small intestine (uroguanylin) or colon (guanylin).
(2)
Linaclotide and plecanatide
Differentiate Lubiprostone, Linaclotide, and Plecanatidde in terms of dosing
This secretagogue is small-molecule inhibitor of GI sodium-hydrogen exchange-3
Tenapanor
Dose of secretagogue Tenapanor
small-molecule inhibitor of GI sodium-hydrogen exchange-3
Tenapanor 50 mg BID
How is PEG-based solution different from other osmotic laxatives in terms of action
polyethylene glycol (PEG)–based solution is iso-osmotic and induces bowel movement by high-volume lavage.
chronic use of THIS LAXATIVE may result in severe hypermagnesemia in patients with renal impairment.
chronic use of magnesium hydroxide may result in severe hypermagnesemia in patients with renal impairment.
Frequent sodium phosphate–based bowel cleansing should be avoided as this is associated with 3 elec abnormalities
Frequent sodium phosphate–based bowel cleansing should be avoided as this is associated with
* Hyperphosphatasemia
* Hypocalcemia
* Hypokalemia
Frequent use of this LAXATIVE should be avoided as this is associated with hyperphosphatasemia , Hypocalcemia, Hypokalemia
sodium phosphate–based bowel cleansing
most thoroughly studied antibiotic for the treatment of IBS.
Rifaximin
Dosing of Rixamin vs Neomycin for patients with IBS
These are nondigestible food ingredients that stimulate growth and/or activity of bacteria in the GI tract.
Prebiotics
only antibiotic with demonstrated sustained benefit beyond therapy cessation in IBS patients
Rifaximin
live microorganisms that when administered in adequate amounts in IBS patients confer a health benefit on the host.
Probiotics
These 3 bacteria are used or found in probiotic agents
- Bifidobacterium breve
- Bifidobacterium longum
- Lactobacillus acidophilus
Effect of probiotics in each the ff IBS symptoms:
* abdominal pain
* bloating
* stool frequency
* stool consistency
These FODMAPs (2) induce IBS symptoms in a dose-dependent manner.
Fructose and fructans
For patients with more severe constipation, may use these drugs (3)
- chloride channel opener (lubiprostone)
- GC-C agonist (linaclotide or plecanatide)
For IBS patients with predominant gas and bloating, may give these… (3)
For IBS patients with predominant gas and bloating, a
* low-FODMAP diet
* Probiotics
* Rifaximin
Prevalence of mild vs moderate vs severe IBS
3 drugs that can be given for diarreha predominant IDS
3 drug classes that can be given for abdominal pain predominant IDS
3 drug classes that can be given for bloating predominant IDS
