Pathophys of Diarrhea Flashcards
T or F: Daily ingestion makes up the majority of liters that enter the gut everyday.
False, 6.5 Ls come from the saliva, gastric secretions, bile, pancreatic secretions, and small intestinal secretions. Only 2L from ingestion
Where is the majority of fluid absorbed?
Small Intestines
In the small intestine, what transports (2) are the main stimulus for water reabsorption?
Na/glucose co transporter and Na/H exchanger
because Na is the main factor for water reabso
In the large intestinal crypts, what transporter is the main one associated with water reabso?
epithelial Na channel ENaC
What are pathophysiologic mechanisms of increased intraluminal fluid?
decreased absorption (osmotic mech) increased secretion (secretory) inflammation
What are some causes of osmotic diarrhea?
lactose, sorbitol and mannitol, lactulose (a rx for hepatic encephalopathy)
Mg compounds, Golyetly, fleets phosphosoda prep
What is the one key to secretory diarrhea?
excessive Cl secretion into the gut
What is the mechanism of cholera?
It secretes a toxin which activates adenylate cyclase in the enterocyte, which increases camp levels, leading to increased activation of CFTR (cl channel) and decreased Cl reabso
Why is CF still around?
May provide a selective advantage over cholera because that channel responsible for cholera isn’t present as a functional channel
The oral rehydration formula for cholera takes advantage of what channel on the enterocyte?
na glucose co transporter. it’s a glucose high salt drink
What are causes of secretory diarrhea?
cholera, e.coli, yersinia dulcolax cholinergics, prostaglandins bile, arsenic, caffeine, etoh neuroendocrine tumors (VIPoma, medullary carcinoma of thyroid)
What are clinical fts of osmotic diarrhea?
moderate volume, resolves with fasting, flatulence, stool ph less that5.3, osmolar gap over 125
what are clinical fts of secretory diarrhea?
voluminous, watery, persists with fasting, no flatulence, stool ph 6-7, osmolar gap less than 50
Should stool osmolarity be the same as serum osm?
yes
What is the inflammatory mechanism for diarrhea of parasites, food allergies and celiac sprue?
mast cells
what is the inflammatory mech for diarrhea of salmonella and whipples ibd
phagocytes, macrophages, neutrophils, eosinophils
inflamm mech for diarrhea of gvh?
t-lymphocytes
inflamma mech for diarrhea of shigella and rotavirus?
direct toxins
Clinical approach to acute diarrhea
less than 3 weeks infectious secretory or inflammatory self-limited tx - mostly supportive
What is the cause of infxs diarrhea associated with aids?
cryptosporidium
With pseudomembranous colitis, what do you see on histology?
fibrin, neutrophils, volcano-like, somewhat bloody
medical management of acute diarrhea is based on what major factor?
if they are becoming dehydrated
What are risk factors for c. difficile?
antibiotic usage, extremes of age, hospitalization
How do you dx c. difficile infxn/
pseudomembraneous colitis on endoscopy, stool assay
