11 - Diarrhea Flashcards
definition of diarrhea
inc fecal weight or inc fecal water (>250g?)
4 pathophys of diarrhea
secretory
osmotic
dysmotility
exudative
max absorptive capacity of colon
4-6L water (per 24 hrs)
secretory diarrhea - cells? volume? osmotic gap? change w/ fasting?
no cells
large vol >500 g/d
no osmotic gap
persists w/ fasting
osmotic diarrhea - cells? volume? osmotic gap? change w/ fasting?
no cells
large vol >500 g/d
osmotic gap >100 mOsm/L
dec w/ fasting (usually caused by exogenous substance)
dysmotility diarrhea - cells? volume? osmotic gap? change w/ fasting?
no cells
small vol
no gap
dec w/ fasting
exudative diarrhea - cells? volume? osmotic gap?
pos for RBCs/WBCs
small volume
no gap
list approach to finding cause of diarrhea
5 I, 4 D, 3 C, 2 M, 1 E
infection, idiopathic, IBD, IBS, incontinence
drugs, diverticular dz, dietary, diabetes
cancer, colitis, collagenous colitis
malabsorption, mechanical
endocrine
how to calc stool osmotic gap
2*(Na+K)
causes of osmotic diarrhea
lactose intolerance, lactulose therapy, gut lavage solutions (colon prep), MgSO4, fructose malabsorption, mannitol, sorbitol, general malabsorption
causes of secretory diarrhea
infxn - cholera, e coli, c perfringens neoplastic (hormone mediated) - includes ZE, or villous adenoma (non hormone mediated) bile salt malabsorption idiopathic some laxatives
causes of exudative diarrhea
infxn (invasive) - shigella, salmonella, campy, c diff, amoeba IBD vasculitis radiation ischemia`
causes of diarrhea related to dysmotility
IBS
diabetes
collagen vascular disease
AIDS enteropathy
partial villous atrophy
malabsorption, wasting, diarrhea
H2 breath test used in dx of diarrhea to…
distinguish between categories of causes of osmotic diarrhea:
pos - lactose intolerance or bacterial overgrowth
neg - investigate other causes
