diarrhea Flashcards
which NT are released by enteric neurons?
VIP and Ach. both stimulate epithelial cells to secrete chloride
what are 2 other secretagogues that are released from local enteroendocrine cells
prostaglandins, histamine
what do bile salts do to secretion?
increases chloride.
what does aldosterone do to the gut?
increases expression of transporters for Na reabsorption
what effect does increased motility have on absorption
decreases it
what effect does inflammation have on absorption
it increases secretion and decreases absorption
definition of acute diarrhea
less than 4 weeks
chronic diarrhea
> 4 weeks
what is the typical clinical course of viral or bacterial diarrhea?
self-limited of lecithin 7 day
what is the most likely cause of infectious diarrhea that lasts longer than 7 days
protozoan
is chronic diarrhea likely to be infectious?
no
how is osmotic diarrhea classified
increased osmotic load tot eh intestines decreases the absorptive capacity because of gradient. there is NO increased secretion. if the osmotic load is not presented to the intestines then there is no diarrhea. t
what syndromes cause an osmotic diarrhea
malabsorption and maldigestion. there are typically no nocturnal episodes.
how to calculate the osmolar gap of the feces
stool gap: 290 - 2x (Na + K)
what if the stool osmolar gap is < 50 and the Na+ > 90
secretory diarrhea
what if the stool osmolar gap is >125 and the stool Na <60
osmotic diarrhea
what are the two disorders that are characteristic of endogenous osmotic diarrhea caused by intraluminal maldigestion?
cholestasis and pancreatic insufficiency
what are the two things that can cause endogenous osmotic diarrhea due to mucosal malabsoprtion
enteropathies and rugs
what can cause exogenous osmotic diarrhea with post mucosal obstruction
lymphangiectasia
what is characteristic of cholestasis?
decreased bile salts and fat malabsoprtion
what is characteristic of pancreatic insufficiency
maldigestion/malabsoprtion of carbohydrates and lipids
common enteropathies
celiac diease, lactose intolerance, infections
celiac disease
gluten enteropathy that causes mucosal inflammation in the proximal bowel. there is villous atrophy and decreased surface area for absorption
lactose intolerance
decreased lactase in surface absorptive cells. the lactose load causes fermentation and thus an increase in the osmotic load.
how do infections cause enteropathies
damage to the brush border causes malabsorption. giardia, cryptosporidium, isospora, strongyloides, MAI, rotavirus.
whipples disease
infiltrate that causes lymphatic obstruction that causes lymphangiectasia
thyrotoxicosis
rapid intestinal transit causes malabsorption
what happens in small bacterial overgrowths
deconjugation of bile salts leads to steatorrhea, there is carbohydrate malabsorption, protein malabsorption, and altered bowel motility
where is bicarb secretion most prominent and what is the mechanism
in the proximal duodenum and is an electroneutral mechanism with chloride. through the CFTR channels.
what stimulates carbonate secretion?
cAMP, cGMP, calcium
what causes secretory diarrhea
when there is an increased chloride secretion resulting in fluid losses exceeding absorptive capacity
what are the causes of secretory diarrhea
can be infectious or non. usually not related to food intake because there are nocturnal episodes seen.
what is the stool osmolar gap in secretory diarrhea
<50
what are the clinical syndromes
hypokalemia and hypochlorydia
what tumors can cause secretory diarrhea.
VIPoma, medullary carcinoma of the thyroid, systemic mastocytosis, villous adenoma, gastrinoma (zollinger-ellison syndrome)
bile salt diarrhea caused by what. what two syndromes of BSD does this cause? what are their mechanisms
disease or resection of the terminal ileum. causes 2 different syndromes of BSD 1.) decreased bile acid absorption and pool leading to fat malabsorption and steatorrhea 2.) there is increased bile salt acid delivered to the colon which induces a secretory diarrhea.
what are the labs for decreased bile acid absorption and pool?
serum bile acids are low, fecal bile acids are low. stool + fat.
what are the labs when there is increased bile salt acid delivered tot he colon?
serum bile acids will be normal and the fecal bile acids will be high
how do we diagnose bile salt diarrhea?
C-triolein breath test