Diarrhea Flashcards
Def
Pathologic mechanisms
abnormally liquid/unformed stools for > 4wks
Osmotic, secretory, motility, malabsorption, inflam
Enhanced mucosal secretion
Characterized by
Common causes
Process
Other drugs
secrete isotonic fluid into lumen, leads to secretory diarrhea
persistence of diarrhea w fasting bc fluid is secreted from mucosa
SE of meds- stimulant lax
activate AC, release cAMP, releasing Cl into lumen, followed w water, Na, K, bicarb
inhibit Na/K ATPase, mainting extra fluid in lumen
Colonic secretion cause of secretory diarrhea
Dec SA leads to
Worsens w
imrpoves w
stim by any condition that limits ileal reabsop of bile acids (SI resection, mucosal disease, fistula)
greater volume of fluid to colon
eating
fasting
Hormonal cause of secretory diarrhea
Carcinoid sydnrome
VIPoma
Final cause
arise from tumors w a wide variety of bioactive products, stimulate SI secretion of fluids/electrolytes
HypoK achlorhydria syndrome, massive watery diarrea
Gastrinoma
Osmotic diarrhea
stool vs serum osmolarity
Non-absorbable osmotic agent in intestinal lumen
Osmotic lax
Sugar free foods
Toddlers diarrhea
Common condition in adults
equivalent
retains water
causative, nonabsorbale carbs (polyethylene glycol, sorbitol, mannitol, lactulose, Mg meds)
poorly absorbed sugars, watery diarrhea
Inc cons of fructose/sorbitol- absorbed via GLUT 5 by fac diffusion (1/2 effective as SGTL1 of gluc/galac)
Brush border disaccharidase def of lactase- cant break down lactose, unabsorbed
Inc intestinal motility
Dz such as
DAN
Hyperthyroid
Rapid transit, contact w bowel mucosa is limited (less absorption)
IBD- inc colonic motility w meals/visceral hypersensitivity to intestinal distension
impaired intestinal motor func- delated/accel bower transit
Hyperdefecation, mutliple loose BM daily
Malabsorption
Derangement via
Prot, carbs, fats consumed
w/out panc exocrine function
Surgeries that byoass proximal duodenum (Roux en Y)
which nutrient effected most
Diminished bile salt synthesis/reabsr
enzyme secretion/activation to breakdown molecules, absorption, transport
breakdown to smaller units
limited breakdown occurs
limit exposure to panc enzymes
Fat (others have backup mechs)
cirrhosis, colestasis, SI bacterial overgrowth, ileal dz- impair FA absorption
SI bacterial overgrowth occurs in
Results in
at risk includes
Predisposing cx, proliferating nonpatho bacteria in SI
deconjugated bile, reabsorping BA in jejunum
anatomic abnorm (surgical blind loops, stricture, fistula), abnormal motility (DM, CD), organ dysfn (cirrhosis, chronic panc, ESRD)
Second stage of digestion
Main dz
Others
Infectins
Post enteritis syndrome (rotavirus)
Absorb nutrients in intestinal mucosa
Celiac- villus atropy/crypt hyperplasia of D/J impairs nutrient absorption
Whipples from T. whpplei w histiocytic infilatraion of SB mucosa
Giardia- depletes BB enzymes
Abetaliporpoteinemia from def chylomicrons
lead to villous atropy, BB enzyme def
watery diarrhea for 1-2 mnths
Final stage of digestion
Possible cz
leads to
transport of nutreitns from entrocytes into systemic circ
lymphatic obstruction from cong do, trauma, CHD
loss of protein and ineffective fat transfer
Carb malabsorption
uncommon
Usually lactase
Protein malabsorption
Fat malabsorption
consider
usually via lymphatic obst w varyng degree of fat malabsorption
Wl, nutrient def
lipase breakdown, bile salt solubilization, dissociation of micells into FA in jejunum, reabsorption of BA in ileum
Inflammation cz
cytokine release
Localized to ileum
exudative loss of fluid through wall
stim enterocyte secretory mechs, inc intestinal motility
fat malabsorption occurs, losing bile acids
Classic inflamm dz
Microscopic colitis
IC individual
MC
other cz of enteropathy
IBD
SBD malabsorption/ileitis
Colonic dz- small vol stools w mucus/blood (UC)
Inflamm changes in lamina propria of colon- dec NaCl absorption w Cl sec
watery diarrhea from bacteria/virus/parasites
crypto/microsporidium
CMV, M. avium, HIV
Intraabdominal radiation
radiation colitis- epithelial cell atrophy and fibrosis
Vassculitis and mucosal ischemia
