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81 Cards in this Set

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 Frequent stools (> 3/day)
 Soft-liquid stools
Types of Diarrhoea

◦small bowel
◦large bowel
 goes on fasting
 osmotic gap in stool
 eg, lactase deficiency, laxatives,
 continues while fasting
 no osmotic gap
 eg, hormone-secreting tumours, ibd, infections
Abnormal motility
irritable bowel syndrome
Small bowel diarrhoea
large volume
brown or pale
no blood or mucus
may contain undigested food
audible borborygmi
Pain - periumbilical
Examples – coeliac disease, Crohn’s disease, lactase deficiency, drug-induced
Large bowel diarrhoea
small volume
may contain blood and mucus
straining, tenesmus
Pain - lower abdomen
Examples - ulcerative colitis, ischaemic colitis
Oily or greasy
Very offensive
Difficult to flush
Examples – pancreatic insufficiency, advanced coeliac disease and other small bowel mucosal disorders
Symptoms of malabsorption
an immunologically-mediated disorder of the small intestine caused by dietary exposure to triggering proteins in wheat, barley and rye
the hallmark is villous atrophy which resolves after removal of the offending proteins
The manifestat...
an immunologically-mediated disorder of the small intestine caused by dietary exposure to triggering proteins in wheat, barley and rye
the hallmark is villous atrophy which resolves after removal of the offending proteins
The manifestations are often non-gastrointestinal
Immunogenic proteins in coeliac disease

ALL generally refferred to as glutens
Genetics of coeliac disease
Coeliac disease in relatives
First degree 5-10%
HLA-identical siblings 30%
Identical twins >75% +
HLA DQ2 or DQ8 necessary but not sufficient
Coeliac disease and Tissue Transglutaminase
◦Found in gut mucosa as a repair enzyme (cross links extracellular matrix proteins)
◦Deamidates glutamine in gliadin to glutamate
◦Deamidation increases affinity of HLA DQ2/8 antigen-presenting cells for gliadin
◦The gliadin-transglutaminse complex is presented to T cells
◦Immune response leads to tissue

i.e THE COMPLEX is the antigen
Pathogenesis of coeliac disease
Clinical: 1:300 to 1:1000
Silent: 1:100
Occurs in Caucasians and non-Caucasians
The Syndrome of coeliac disease
Antibody Testing in Coeliac Disease
Small Bowel Biopsy Coeliac
Coeliac Disease
Small bowel biopsy is essential
Repeat biopsy after gluten-free diet (6 months or longer)
Gluten challenge and rebiopsy may be needed in children (to DDx viral gastro causes)
Coeliac Disease NON-Dx criteria
Coeliac Tx
• No wheat, barley, rye, (oats)
• Strict
• Life-long

Benefits of a gluten free diet
Improved nutrition
Reversal of metabolic deficiencies
Improvement in bone density
Reduction in malignancy risk
Inflammatory bowel disease - epidemiology
Prevalence up to 1:1000
Developed > developing countries
◦increased prevalence as countries “westernise”
Any age but maximal 15-35 and 50-70
Males = females
Ulcerative colitis
confined to colon
rectum always involved
continuous inflammation for a variable distance
•proctitis to pancolitis
mucosa only affected
Crohn’s disease
any part of GIT
•mostly ileum, colon or both
transmural inflammation
•mucosa + submucosa
•deep ulcers, fissures
discontinous inflammation
•“skip” lesions
strictures and fistulae
granulomas typical (70%)
Genetics and Crohn’s disease
Complex and non-Mendelian
Increased risk in families
– 3-20x increased risk in 1st degree relatives
Concordance for site and clinical type in families
Heterogeneity in HLA II studies
Crohn’s disease – NOD2, IL-23R, ATG16L1
Multiple loci identified in Crohn’s disease and ulcerative colitis
Ulcerative colitis
- bleeding
- diarrhoea
- constipation if proctitis (rectal)
- pain if severe
A mucosal disease
Crohn’s disease - distribution
Crohn’s disease
- abdominal pain - diarrhoea if colonic involvement - constipation if ileal disease - bleeding ~ 50% - weight loss - systemic symptoms – fever, malaise, etc - impaired nutrition, esp. children - stenosis/obstruction - fistulas
A transmural disease
Crohn’s disease - fistula
entero-enteric enterocutaneous enterovesical rectovaginal perianal
entero-enteric enterocutaneous enterovesical rectovaginal perianal
IBD – systemic complications
Ulcerative colitis –and cancer risk
Ulcerative colitis – increased cancer risk
Ulcerative colitis – increased cancer risk
Diagnosis of IBD
◦duration and nature of symptoms, F/H, etc
Stool examination and culture
◦exclude infection
Colonoscopy +/- other endoscopic modalities
◦CT, MR, barium studies, AXR
◦granulomas specific for Crohn’s disease but 70% only
◦acute and chronic changes
Management of ulcerative colitis
◦5 –aminosalicylic acid – sulphasalazine, mesalazine, olsalazine, balsalazide
◦corticosteroids - prednisone, budesonide
◦immunosuppressives - azathioprine/6-MP,methotrexate, cyclosporin, etc
◦biologics - infliximab, adalimumab
Surveillance for carcinoma
Severe or resistant disease – surgery (ileoanal pouch or ileostomy)
Ulcerative colitis surgical options
Management of Crohn’s disease
◦5 –aminosalicylic acid – sulphasalazine, mesalazine, olsalazine, balsalazide
◦corticosteroids - prednisone, budesonide
◦immunosuppressives - azathioprine/6-MP,methotrexate, cyclosporin, etc
◦biologics - infliximab, adalimumab
◦antibiotics if infection/abscess
◦perinal disease
Irritable bowel syndrome
A functional disorder of the gastrointestinal tract manifested by:
◦abdominal pain
◦disturbed defaecation
Irritable bowel syndrome
◦10-15% of the population affected
◦20-50% of referrals to gastroenterologist
◦Females > males 2:1
◦Any age
50% onset < 35years
90% onset <50 years
◦Important condition
time lost from work (2nd only to the common cold)
medical costs
Irritable bowel syndrome
Clinical features
◦Abdominal pain
◦Altered bowel habit
diarrhoea &/or constipation
◦Upper GI symptoms
◦Non-GI symptoms
Extraintestinal symptoms in IBS
so maybe a gut-brain syndrome
so maybe a gut-brain syndrome
Irritable bowel syndrome
Features against a diagnosis of IBS
◦rectal bleeding
◦weight loss
◦nocturnal symptoms
◦first symptom > 50 years of age
◦recent change in symptoms

Lactose intolerance/lactase deficiency
◦10% adults
◦Asians/Africans > caucasians
Can be secondary
◦gastroenteritis; giardiasis; coeliac disease, etc
Symptoms similar to IBS
◦diarrhoea, flatulence, bloating, rumbling
◦history, SB biopsy, lactose breath test, lactose-free diet
Treatment – lactose-free diet; lactase supplements
Chronic Diarrhoea
Basic Pathophysiology
• Imbalance between absorption and secretion
– Gut secretes ~9L of liquid /day
– Stool volume usually about 200mL/day
– Major function of the colon is to absorb liquid
• So…..
– Increased secretion
– Decreased absorption
– Increased transit
will all lead to increased liquid excretion
• Significant weight loss
• Bleeding
• Systemic symptoms (eg: fever, arthralgias)
• Evidence of inflammation
• 23 year old PhD student at Sydney University
• In Sydney (from Hong Kong) for 2 years
• Previously well
• Episodic diarrhoea for ~12 months
• Seems to be worse during term
– “my supervisor is a jerk”
• Characteristics:
– Mostly post-prandial
– Resolved during a 48hr fast
– Associated periumbilical cramping, rumbling
– “Mushy”
– No blood
– Up to 3-4 times per day
– Otherwise feels well, weight stable
– Good exercise tolerance, etc
– No significant family history
• Physical Examination
– Well
– Normal physique
– Afebrile
– Abdomen soft, non-tender
– Normal bowel sounds
– Otherwise normal
• Rigid sigmoidoscopy:
– Normal appearing rectal
• Investigations:
– Full blood count
– Erythrocyte sed. rate
– C-Reactive protein
– Thyroid function
– Stool microscopy/culture/sensitivity
-all normal
• Upper endoscopy:
– Normal upper gut appearance
– A diagnostic test was performed……
• Small bowel biopsy for disaccharridases:
– Lactase 3 (20-135 U/g prot.)
– Sucrase 80 (35-280 U/g prot.)
– Maltase 270 (60-930 U/g prot.)
Feels well after abstaining from milk products
• -That all took weeks and cost thousands
• Nothing wrong with a clinical approach
– Avoid lactose for two weeks
– Then challenge

Diagnosis = lactose intolerance
• The main clue is that the diarrhoea resolved
after a 48 hour fast
– osmotic diarrhoea
• Confirmed by
– Normal endoscopy with selective intestinal
lactase deficiency
– Response to lactose reduced diet
Lactase Deficiency
• Congenital
• Acquired (primary Adult)
• Secondary
Acquired Lactase Deficiency
• Usually develops before age 6
• 50% will develop symptoms with 200 ml milk
• Bloating, discomfort, flatulence, diarrhoea
Lactase Deficiency World-Wide
• Northern European: 2 to 15%
• Latino patients: 50 to 80%
• Ashkenazi Jews: 60 to 80%
• African Americans: 60 to 80%
• American Indians: 80 to 100%
• Asians: 95 to 100%
Diagnosis of Lactase Deficiency
• Association of typical symptoms with lactose
intake, relief by 1 week lactose free diet and
+ve re-challenge
Special tests (usually not necessary)
• Hydrogen breath test
• Specific lactase assay of small bowel biopsy
Lactase Def. Mx
• Intolerance (due to enzyme def.) is not
• Reduce diary products
– Small amounts of milk are OK
– Lactase tablet or liquid
– Lactose free milk
– Soy milk
• Maintain calcium intake
– Tinned fish with bones (are you kidding???)
– Calcium supplements
Chronic Diarrhoea
4 basic mechanisms
• Exudation (bowel disease)
• Osmotic
• Secretory
• Motility
Osmotic Diarrhoea
• Poorly absorbed osmotically active agent
within lumen
• Faecal H2O rises in parallel
• Diagnosis:
– Stops when solute removed (or total fast)
– Increased Osmotic gap
Osmotic gap
• Osmotic gap = 290 - 2 x (Na+K)
• Stool cannot sustain osmotic gap with plasma
so rather than osmolality rising, Na/K
concentrations fall in presence of osmotic
Causes of osmotic diarrhoea
• Carbohydrate malabsorption
– Excessive ingestion of poorly absorbed CHO (lactulose,
sorbitol, mannitol, fructose, fibre)
– Malabsorption (lactase or other enzyme deficiency)
• Other solutes
– Bowel prep (PEG, citrate, sulfate, phosphate)
Case 2
• 56 year old with 2-3 loose BMs per day
• Slowly progressive over 2 years
• Feels lethargic but ~well
• Good appetite
• Lost 10kg over past year
• Past history:
– 6 hospitalisations with abdominal pain in 1990s
• Diagnosis of recurrent acute pancreatitis
• No episodes of pain for >1year
– Recent diagnosis of diabetes mellitus
• On oral Rx
– Practising Barrister
– Smokes 50 cigs/day
– Drank ~100g alcohol/day until mid 90’s
• ~10 standard drinks
• Characteristics of diarrhoea:
– Minimal hypogastric cramping
– 3-4 times/day
– Large volume with oil droplets
– Wife makes him use outside loo:
• “Smells like someone cut a dog in half”
– Difficult to flush
– No blood
– Confirmation of the “type” of diarrhoea
– Confirmation of the underlying process
• Confimation of the “type” of diarrhoea
– 72 hour faecal fat determination (yuk):
• 90 g fat (Normal <5g/day)
• Confirmation of the underlying process:
– Options:
• Pancreatic exocrine function testing
• Pancreatic imaging
• Progress
– Started on pancreatic enzyme replacement with each
– Resolution of diarrhoea
– Gaining weight
Rumbing noise
means inc peristalisis
Hypogastric cramping
means clonic sounding
Mechanism of diarrhoea in
chronic pancreatitis
• Maldigestion - failure to digest fat when
<10% function remains. Protein/cho
maldigestion is lesser problem
• Presentation
– abdominal pain (pancreatic),
– weight loss,
– Diarrhoea, vitamin deficiencies, and
– Diabetes often co-exists
Maldigestion v Malabsorption
• Maldigestion
– Digestion takes place within the lumen
– Requires enzymes, bile salts, correct pH, appropriate
motility/contact time
– eg pancreatic failure
• Malabsorption
– Absorption is a mucosal function
– Requires intact mucosa, brush border enzymes
(transport, disaccharidases), blood & lymph
– eg coeliac disease
Management of chronic alcoholic
• Abstinence from alcohol
• Enzyme supplementation
• Acid suppression
• Analgesia
– Significant risk of opioid dependence
• Endoscopic therapy?
• Surgery?
When someone says they are a barister
think alcholic
Case 3
• 25yr old with long history of intermittent
“nagging” symptoms:
– Bloating
– Loose stools
– Lethargy
– Preesented when rejected from donating blood
due to anaemia
• Hb:110; microcytic
Coeliac Disease (Sprue)
• Hypersensitivity to gluten (protein)
– Wheat
– Barley
– Rye
• Corn and rice (but not oats) are OK
• Broad Spectrum of Disease
– Australian Study (Busselton, WA):
– 1:250
– 50% asymptomatic
Pathogenesis of Coeliac
• DQ2: 90% of coeliacs
20% of general population
• 10% have a first degree relative with CD
• Autoantigen: Transglutaminase (tGT)
– Catalyses glutamine to glutamate
– Deamidates glutamine at posn 65 of A-gliadin
– The tGT-gliadin complex stimulates an immune
response in coeliac disease
Common Features of Coeliac
• Steatorrhoea (most do NOT have this)
• Osteomalacia / osteoporosis
• Anaemia (Fe def. / Folate def.)
• Miscarriages
• Splenic atrophy
• Angular stomatitis
• Weight loss
• Abdominal pain, bloating
• Depression
• Lethargy
Case 4
• 22 year old medical student
• 3 month history of diarrhoea
• Associated generally unwell
– Lethargic
– Lost ~2kg
• Characteristics:
– Up to x10 per day
– Small amounts
– Assoc. hypogastric cramping
– Mushy, “slimey”
– Noticed small amount of blood ~50% of time
– Feeling on incomplete evacuation
• No recent travel or antibiotics
• Investigations:
– Full blood count Mild normocytic anaemia
Mild leucocytosis
– Eryth. sed. Rate 50mm/Hr (N: <10mm/Hr)
– C-Reactive protein 60 U/L (N: <5U/L)
– Stool Examination:
• No parasites
• Profuse RBCs and WBCs
• Normal culture
• A diagnostic test was performed…….
– Ulcerative colitis
– Crohn’s colitis
– Infective colitis
• Biopsies consistent with ulcerative colitis
• Rx:
– rectal steroid foam
– Oral sulphasalazine
Sigmoidoscopy in IBD
Diarrhoea in IBD
• Exudative
• Associated with inflammation
• Stool contains mucus, exudate and blood
• Continues despite fasting
• Poor rectal compliance
= frequent, small stools
Approaches to diarrhoea
1. Are we sure this is diarrhoea?
eg: incomplete evacuation = ???? Rectal mass
1. Does it fit a common disorder?
3. Pathophysiological approach
Commonest causes of “diarrhoea”
• Irritable Bowel Syndrome
• CHO malabsorption (lactose intolerance)
• Recent antibiotics (C. difficile or
• Drugs (and alcohol)
Irritable Bowel Syndrome
• Clinical hallmark:
– abdominal pain associated with altered bowel
habit, pain relieved by defaecation
• Absence of other pathology
• Pathophysiology:
– altered motility of unknown cause (minimal
inflammation, altered CCK, serotonin and
neurokinins) with abnormal sensitivity to
• Beware of patients with water bottles
Alcohol and diarrhoea
• Altered motility
• Altered permeability
• Small intestinal mucosal injury separation of
the tip of the villus epithelium forming blebs
(malabsorption of various nutrients)
• Pancreatic disease (malabsorption)
• Faecal impaction may also present
with diarrhoea
• Some people with normal stool
volume complain of diarrhoea
Faecal Incontinence
• May accompany diarrhoea
– Severe &/or
– Elderly
• Many report “diarrhoea” rather than
incontinence due to embarrassment
– Careful history taking
– Assess rectal tone, neurological examination
Pathophysiological Approach to
• Altered bowel integrity
• Osmotic
• Secretory
• Motility
Altered bowel integrity
• Bowel diseases, eg inflammation, neoplasia,
infection (eg HIV)
• Fistula (eg: s. bowel to colon)
• Short bowel
– BUT diarrhoea is not usually a prominent
feature of small bowel Crohn’s disease
• Localise to site (eg large vol-small bowel)
• Endoscopy/biopsy/ barium studies
Osmotic diarrhoea
• Commonest example is lactose intolerance
• Sorbitol
• NB: Lactulose
• Non-absorbable solutes attract water into lumen
• Surreptitious laxative abuse
Secretory diarrhoea
• Hallmark is continuing diarrhoea despite
complete fast
• May need to admit and keep nil by mouth with IV fluids
• Absence of blood or inflammation
• Usually acute diarrhoea, not chronic
Commoner secretory diarrhoeas
(none are common)
• Luminal secretogogue
– Bile salt diarrhoea
• Loss of <100cm terminal ileum
– Bacterial toxins
• Cholera toxin
• Circulating secretogogue
– Tumours (VIPoma, MTC, Carcinoid, Z-E syndrome)
• Too fast
– Thyrotoxicosis
– Post-abdominal surgery
– IBS/ just before a viva exam
• Too slow (produce bacterial overgrowth)
– Primary intestinal hypomotility (elderly)
– Scleroderma, diabetic autonomic neuropathy
• Abnormal
– Irritable bowel syndrome