B5-020 Diarrhea Flashcards
the colon takes up approximately […]% of the fluid presented to it
90
when the large reserve capacity of the small intestine and colon is exceeded or impaired […] manifests
diarrhea
the site for intestinal fluid movement is the
epithelial lining
has specialized properties for fluid movement
epithelial lining
restrict passive flow of solutes once secreted or absorbed
tight junctions
normal crypt to villi ratio
2 villi to one crypt
movement of solutes and water through tight junctions
paracellular trans epithelial transport
dictated primarily by electrochemical gradient
paracellular trans-epithelial transport
requires membrane transport proteins to drive the transcellular transport of ions
trans-epithelial transport
transport of ions sets up the electrochemical gradient
trans-epithelial transport
electrochemical gradients allow […] transport of fluid through tight junctions
paracellular
primary function is nutrient absorption
villi
primary function is secretion
crypt
primarily depends on Na+ transport
villi absorption
primarily follows Cl- and bicarbonate
crypt secretion
- bricarbonate secretion
- electroneutral NaCl absoprtion
- chloride secretion
occurs where
small intestine
chloride secretion mainly occurs where in GI tract?
colon
calcium and iron absorption occur where
small intestine
what transporter is responsible for sodium glucose reabsorption?
SGLT1
what transporter allows for the secretion of Cl-
CFTR
- solute driven water losses
- more prominent in the colon
osmotic diarrhea
crypt secretion leads to more prominent small intestinal losses
secretory diarrhea
normal osmotic gap
50-100
calculation for osmotic gap
290-2 x (Na + K)
osmotic gap > 100 mosm/kg
osmotic diarrhea
osmotic gap <50 mosm/kg
secretory diarrhea
frequent, small volume bloody stool
inflammatory diarrhea
fundamentally indicates disrupted and inflamed mucosa
inflammory diarrhea
caused by:
* infectious processes
* IBD
* ischemic colitis
inflammatory diarrhea
`
- greasy, bulky stools
- weight loss
- floating feces
fatty diarrhea
osmotic diarrhea, but with fat content
celiac disease causes what type of diarrhea?
fatty diarrhea
fat malabsorption
loss of large volumes without inflammation of enterocytes
osmotic diarrhea
stool volume decreases with fasting
osmotic diarrhea
stool pH <5.3
acidic
normal is 6.6
osmotic diarrhea
caused by:
* giardiasis
* osmotic laxatives
* lactose intolerance
osmotic diarrhea
osmotic laxatives
5
- MiraLax
- milk of mag
- sorbitol
- lactulose
- PEG
caused by an osmotically active substance drawing hypotonic solution into lumen
osmotic diarrhea
caused by ingestion of poorly absorbed sugars or ions
osmotic diarrhea
loss of large volumes of isotonic watery diarrhea without inflammation
secretory diarrhea
stool volume continues unabated by fasting
secretory diarrhea
stool pH usually 6.6
normal or close to normal
secretory diarrhea
caused by increased Cl- channel activation via increased cAMP
secretory diarrhea
is further workup necessary for acute diarrhea?
no
- CRP and ESR elevated
- low serum albumin
inflammatory diarrhea
curved rods
gram negative
2
c. jejuni
vibrio
- common in southern states
- through summer (May-Aug)
- found in oysters
vibrio parahaemolyticus
improves with fasting
osmotic diarrhea
osmotic gap >125 mosm/kg
osmotic diarrhea
what does a high magnesium output indicate?
laxative abuse
inadvertent digestion
- associated with laxative abuse
- damaged cells express pigmentation
melanosis coli
sorbitol should be limited to
10 g/day
what kind of laxative is Senna?
stimulant
stimulant laxatives increase
2 things
motility and secretions
stimulant laxatives cause […] diarrhea
secretory
absorbed carbohydrates and sugar alcohols intaken orally in large quantities cause
osmotic diarrhea
do enzymes help digest polyol/sugar alcohols?
no
measures anaerobic bacteria production of hydrogen from undigested sugars
hydrogen breath test
osmotic gap <50
secretory diarrhea
what additional test may you want in the setting of secretory diarrhea?
colonoscopy
sigmoidoscopy
CT scan
indomethacin inhibits […]
prostaglandins
reduces Cl- pumped into lumen
how does an adenoma cause secretory diarrhea?
- adenoma secretes PGE2
- PGE2 stimulates increased intracellular cAMP
- cAMP phosphorylates CTFR
- CTFR allows Cl- movement into small intestine. water follows -> secretory diarrhea
villous adenomas secrete electrolytes and mucin causing secretory diarrhea and dehydration
McKittrick Wheelock syndrome
pre-renal acute kidney injury
* hyponatremia
* hypokalemia
* elevated creatine
McKittrick Wheelock syndrome
treatment for secretory diarrhea caused by adenoma
NSAIDs can be supportive but must be resected
- reduced duodenal folds
- no duodenal villi
- increased intra-epithelial lymphocytes
- no villi
celiac
anti-TTG IgA
anti-gliadin IgA
are markers for
celiac
what kind of diarrhea does celiac disease cause?
osmotic
unabsorbed nutrients pull fluid into the lumen
how does celiac cause issues with bone health?
- decreased Ca+ absorption in small intestine
- decreased serum calcium signals thyroid to release PTH
- PTH signals for increased calcium uptake from bones and kidneys
autoimmune disease where consumption of gluten will lead to damage of small intestine
celiac
associated with bone health issues
celiac
treatment for celiac
strict gluten free diet
dermatitis herpetiformis is associated with
celiac
decreased stool pH is associated with
lactose intolerance
what kind of diarrhea does lactase insufficiency result in?
osmotic
T. whippelii presents with
4
- fever
- steatorrhea
- joint pain
- fatigue
celiac can lead to decreased […], resulting in edema
albumin
usually experiences some benefit with loperamide and diet change
IBS
pancreatic exocrine insufficiency causes
frequent loose, foul smelling stools (steatorrhea)
- bloody stools
- abdominal pain
- fever
- elevated CRP
- low Hb
- low albumin
UC
frequent watery, non-bloody diarrhea and abdominal cramping
collagenous collitis
gram negative non-motile rods in a stool sample can belong to which two genera?
campylobacter and vibrio
continue to grow at 4 degrees C
2
- yersinia
- listeria
causes issues with refrigerated blood supplies
yersinia
causes issues with refrigerated foods
listeria
thiosulfate citrate bile salts sucrose agar is selective for
vibrio