Diarrhoea & Malabsorption Flashcards by Jason Hsu

where is most fluid in GI absorbed?

proximal small bowel

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Why pain with claudication?

lactic acid build up from hypoxaemia

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iron absorbed where?

jejunum

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where is B12 absorbed?

terminal ileum after binding to intrinsic factor and factor R in presence of acid

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diarrhoea is abnormal what?

frequency and liquidity of stool that can cause excess fluid and electrolyte loss

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when is diarrhoea chronic?

more than 4 weeks

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3 big things to consider in diarrhoea?

volume
at night?
blood and mucous?

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normal bowel movement schedule?

every second day to 2-3times a day

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what if they have diarrhoea at night?

might be organic problem, not diet

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4 mechanisms of diarrhoea?

osmotic
secretory
inflammatory
altered intestinal motility

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what can cause osmotic diarrhoea?

mannitol, 
sorbitol
lactose
fructose
magnesium,
 phosphate
excess unabsorbed substrates in gut lumen

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what causes secretory diarrhoea?

cholera
ETEC
hyperthyroidism
tumours

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what causes inflammatory diarrhoea?

Ulcerative colitis

Crohn’s

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what is faecal calprotectin for?

screening to see if need colonoscopy

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PCR in stool to check for?

Norovirus, C. Diff

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what if there are WBCs in stool?

indicates inflammatory cause

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faecal elastase is a marker of?

pancreatic sufficiency

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mechanism of secretory diarrhoea?

active anion secretion of enterocytes caused by bacterial toxins: ETEC, Cholera

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fasting does what to secretory diarrhoea?

persists

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fasting does what to osmotic diarrhoea

helps

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mechanism for inflammatory diarrhoea?

altered membrane permeability

invasive bacteria: Shigella, salmonella, C Diff, campylobacter, entamoeba histolytica, CMV, IBD

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3 causes of rapid transit causing diarrhoea?

hyperthyroidism
drugs
IBS

2 causes of slow transit?

bacterial overgrowth>nutrient consumption»bile salt inactivation»
anatomical: strictures, blind loops, surgical

2 kinds of malabsorption:

intraluminal

2. intramural/transport

where to look for muscle wasting?

Thenar eminences

mechanism of pernicious anaemia?

autoimmune against stomach parietal cells

3 causes of luminal phase maldigestion?

pancreatic insufficiency cholestasis bacterial overgrowth

3 causes of mucosal phase/defective transport

1. not enough intestine 2. coeliac, crohn's, brush border enzym deficient 3. transport: lymphoma obstruction, radiation damage

tenesmus means?

unsatisfactory feeling after defecation

common causes of 'dysentry'?

Salmonella shigella yersinia entamoaba histolytica

difference in histology between UC and Crohn's?

Crohn's has granulomas

UC affects what?

only the mucosa in the large bowel

UC has a higher risk of getting what?

primary sclerosing cholangitis>>bowel cancer

how to tell between UC and Crohn's?

UC always affects rectum, get urgency and tenesmus. | UC has no skip lesions

anyway to cure UC?

surgery

anyway to cure Crohn's?

Nope

histological features of Crohn's?

focal transmural inflamm, granuloma's skip lesions affect from mouth to anus

extra-intestinal features of Crohn's?

arthritis uveitis rashes

time course of crohn's?

relapsing/remitting over many years

what is classic presentation of Giardia?

rice-water stool, nausa and small volume

typical history of IBS?

at least 3 mo hx abdo pain with: -better with defecation -change in stool form and frequency

Coeliac disease dx?

biopsy with symptoms | biopsy after gluten free diet

Coeliac screening?

blood test to measure Abs to transglutaminase deamidated gliadin peptides

what 4 things can show villous atrophy in biopsy?

coeliac tropical sprue H. pylori Giardia

what gene for coeliac?

HLA-DQ2/8

how to dx if already on gluten free diet?

6-week gluten challenge

what is a key mediator in IBS?

serotonin (5-HT)

IBS, what happens to motility?

disordered

IBS what kind of hypersensitivity?

visceral hypersensitivity of nociceptive stimuli

possible triggers of IBS?

bacterial overgrowth | 'stress'

what are FODMAPS?

``` Fermentable: Oligosaccharides: starches in beans Disaccharides: lactose Monosaccharides: fructose POlyols: sorbitol, mannitol ```

FODMAPS contribute to which disease?

Irritable Bowel Disease, FODMAPs are poorly absorbed

3 main treatment modalities for IBS?

dietary: no FODMAPS pharmacological: probiotics, ABx Psychological: relaxation

how to test for bacterial overgrowth?

hydrogen/methane breath test