Chapter 9 - Diarrhea And Constipation Flashcards
Osmotic diarrhea osmotic gap
> 50 mOsm/kg suggestive
100mOsm/kg specific
Secretory diarrhea osmotic gap
<50 mOsm/kg
Enterotoxigene E.coli mechanism
Adhere to specific glycoprotein receptors on the intact microvillous membrane by means of pili which permits colonization
Enteropathogenic E.coli mechanism
Obliterate microvilli, producing pedestals to which they adhere
Shigella mechanism
Internalized by endocytosis and spreads laterally from cell to cell
Salmonella mechanism
Penetrates the brush border and tight junction to gain access not only to the mucosa, but also to the bloodstream
Cholera toxin mechanisms
- binds to apical membrane, internalized, cAMP activation and production. Blocks sodium absorption and stimulates chloride secretion by the entorocytes
- interacts with enteroendocrine cells and enteric nervous system altering electrolyte transport and motility.
E.coli STa toxin mechanism
Ligand to brush-border receptor guanylin and uroguanylin, endogenous regulatory peptides produced by enterocytes and distributed intraluminally. Guanylate Cyclase and cGMP production causing Cl secretion.
Campylobacter Jejuni mechanism
Often tissue invasion and severe colitis mimicking UC
E.coli O157:H7: clinical manifestation and source
Hemorrhagic segmental colitis
Hemolytic uremic syndrome
Undercooked hamburger or other foods
C.difficile mechanism
Cytotoxin production that kills enterocytes and produces pseudomembrane colitis
Rome IV criteria IBS
Abdominal pain with 2/3:
- related to defecation
- associated with change of stool frequency
- associated with change of stool consistency/form
Bile acid malabsorption diagnostic strategy
- SeCHAT retention
- C4 or FGF-19 assay
- trial of bile acid sequestrant
SIBO diagnostic strategy
Quantitative culture of small intestinal aspirate
Breath hydrogen testing
Trial antibiotic therapy
What does pH of stoo < 6 indicate?
Excess carbohydrate fermentation in the colon
How much fat to ingest per day for accurate fat output testing?
70-120g
Possible bacteria for chronic diarrhea
Aeromonas and pleisiomonas
Protozoal pathogens in stool requiring modified acid-fast or safranin staining
Cryptosporidium, cyclospora and cystoisospora
Type 1 bile acid diarrhea
Après resection iléale ou dysfonctionnement iléale
Type 2 bile acid diarrhea
Idiopathic
30% patients with IBS-D or functional diarrhea
Due to defective FGF-19 feedback
Serum FGF19 bas et C4 élevé