Malabsorption Flashcards
What is the defn of steatorrhea?
presence of excess fat in feces, >5% of dietary intake
steatorrhea is often a sign of
malabsorption
describe the stool characteristics with steatorrhea
floats and there s grease on top of the water
it stinks
it is hard to flush
what are the mechanisms that causes diarrhea in steatorrhea
- excessive amts of osmotically active particles from malabsorbed dietary components
- hydroxylation of 10-hydroxy oleate which accelerates defecation ??? not sure how this fits in
- the FA in the stool impari fluid and electrolyte abs
how do you differentiate mal-digestion from absorption
d-xylose absorption:
D-Xylose is a monosaccharide, or simple sugar, that does not require enzymes for digestion prior to absorption. Its absorption requires an intact mucosa only. If d-xylose is not absorbed = epithelium problem
What is the secretin test?
tests pancreatic insufficiency as the cause of malabsorption
CCK is admin and should stimulates the pancreatic secretion of bicarb
What does the hydrogen breath test test?
carbohydrate malabs due to overgrowth of bacteria
*if there is an earlier peak of H+, there is more bacteria in the duodenum/proximal intestine
What is the most common cause of steatorrhea?
Pancreatic insufficiency
Why does chronic pancreatitis cause steatorrhea?
Do not make lipases
Why does ZES lead to chronic steatorrhea?
High gastrin levels increase the secretion of gastric acid which lowers the pH of gastric contents to a point that the lipases are not functional
What are 2 intraluminal insufficiencies that lead to steatorrhea?
Lipase and Bile Acid Insufficiencies
What are 4 causes of bile acid insufficiency?
Cholestsatic liver disease
Terminal ileecomy
Small bowel overgrowth
Reduced CCK release
What are 4 causes of lipase insufficiency? (this causes steatorrhea)
Chronic pancreatic
CF
ZES
Post gastrectomy
Why does decreased CCK lead to steatorrhea?
No CCK = GB cannot contral and sphincter of Otti cannot relax, therefore no bible can be released
Why does bacterial overgrowth lead to steatorrhea?
The bacteria will de-conjugate the BA = no reabs of BA for recycling = less BA for solubilizing fats reabs
Why does a terminal ileectomy lead to steatorrhea?
There is no reabs of BA for recycling = less BA for solubilizing fats
Why does cholestatic liver disease lead to steatorrhea?
Cannot secrete bile from hepatocytes to ampulla
What are the effects of impaired circulation of bile salts?
- Diarrhea/steatorrhea
- increased proportion of BA conjugated with glycine than taurine
- increased proportion of deoxycholate in bile
- a reduced bile salt pool size
Malabsorption due to the fact that the cells at the surface of the intestine are immature
Celiac Sprue
Causes of malabsorption in celiac sprue
- intestine in secretory state
- decreased bile salts
- decreased synthesis of complex lipids
- decreased CCK
- decreased absorptive surface area
Celic Sprue increases, decreases, or has no change on the abs of the following:
- disaccharides
- fat
- B12
- Fe ++
- Ca ++
- proteins
All decreased except B12 which is unchanged
Pathogenesis of celiac sprue
Gluten + certain genetic background
How is celiac sprue diagnosed?
Clinical response to exclusion of gluten from diet
Steatorrhea that gets better with administration of steroids
Adrenal insufficiency
