012015 diarrhea Flashcards
diarrhea-malabsorptive vs exudative
malasorptive-inadequate nutrient absorption associated with steatorrhea. relieved by fasting
exudative-due to inflam disease. purulent, blooding stools. continues during fasting
frequent overlap btwn these two
malabsorption results from
at least one of four phases of nutrient absorption
practical definitions of diarrhea
normal bowel movement: one BM every three days to 3 BMs everyday
diarrhea: more than 3 loose/watery stools per day OR a clear increase in frequency and decrease in consistency over baseline
clues to actual diarrhea
consistency urgency incontinence (doesn't make it) nocturnal bowel movements flatuphobia
when diarrhea comes from small bowel as the cause, what is notable?
watery diarrhea, LARGE VOLUME and less frequent
(small bowel fxns to absorb most water, nutrients, minerals, sugars, protein)
abdominal cramping, bloating, gas, weight loss
evidence of MALABSORPTION, VITAMIN, or nutrient deficiencies
fever is rare
rare stool WBCs or occult blood
when diarrhea comes from large bowel as the cause, what is notable?
large bowel usually fxns as storage and absorbs some fluids/electrolytes. when it’s inflamed/dysfunctional, it can’t perform this fxn.
frequent, small, regular stools as opposed to watery
tenesmus (rectal dry heaves)–has to go but nothing comes
painful bowel movement
fever, bloody, mucoid stools
RBCs and WBC on stool smear
osmotic diarrhea
unabsorbed ions remain in the lumen and osmotically active ions pull water into lumen of bowel
causes of osmotic diarrhea
ingestion of poorly absorbed ions or sugars or sugar alcohols:
- -mannitol, sorbitol (in sugar free candy)
- -Mg, sulfate, PO4 (in laxatives)
deficiency of enzyme breaking down disaccharide (ex: lactase)
symptoms of osmotic diarrhea
disappears w/ cessation of offending substance
how does electrolyte absorption fare in osmotic diarrhea?
it’s not impaired
electrolyte concentrations in stool water are usually quite low
secretory diarrhea
net secretion of anions (Cl or HCO3)
OR inhibition of net sodium absorption
most common cause of secretory diarrhea
infection
which is more common: secretory or osmotic diarrhea?
secretory
acute vs chronic diarrhea
acute: symptoms lasting under 14 days
persistent: 14-28 days
chronic: more than 28 days
causes of acute diarrhea
infection (bacteria, parasites, protozoa, viruses) food allergies food poisoning medications initial presentation of chronic diarrhea
causes of chronic diarrhea
fatty diarrhea (causes are malabsorption syndromes, etc) inflammatory diarrhea (infectious diseases, IBD, Crohn's disease) watery diarrhea (many causes)
waking at night with diarrhea
secretory diarrhea, not osmotic diarrhea
what do you want to get in terms of hx from pt presenting with diarrhea
description of diarrhea
past medical history-celiac, IBD recent travel pets (turtles)-Salmonella hobbies (Giardia-drinking from streams) diet-sorbitol, caffeine, large amt of high fructose corn syrup, alcohol intake
med changes (NSAIDs and Olmesartan cause sprue like illness. antibiotic use or chemo can cause C diff infec)
family hx-celiac, IBD
contacts w/ nursing homes, occupational exposure
if diarrhea pt has fever in hx, what should you think of?
invasive bacteria enteric viruses cytotoxic organism (C. diff or Entamoeba histolytica) ischemia IBD
if pt with diarrhea has food history, what should you think of?
if began within 6 hrs–suggests toxin (s aureus or bacillus cereus on rice)
8-14 hours suggests infec w Clostridium perfringens
more than 14 hrs-could be viral or bacterial infection. it’s non-specific
PE for pt with diarrhea like symptoms should look at
initially focus on VOLUME STATUS
signs of other systemic disease (dermatitis herptiformis in celiac disease, erythema nodosum or arthritis in IBD)
abdominal tenderness/mass
rectal exam (fistula, bloody stool)
when should you order stool for pathogens?
when pt is VERY ILL or has RISK FACTORS FOR INFECTION (fever, etc)
immune compromised pt can get diarrhea with what infectious organisms?
giardiasis and cryptosporidium (can do ELISA or DFA microscopy)
stool electrolytes in secretory vs osmotic diarrhea
secretory: small osmotic gap (under 50 mOsm/kg)
osmotic: high osmotic gap (over 100 mOsm/kg)
calculating osmotic gap
serum Osm - est stool Osm
stool Osm is
2 * (conc Na + conc K)
when osmotic gap is negative, suggests
ingested poorly absorbed multivalent anion, such as phosphate or sulfate
stool osmolality’s use
not very useful clinically
one situation in which stool osmolarity may be useful
surreptitious laxative ingestion
chronic diarrhea-the more common causes that should be pursued early in diagnosis
celiac disease
thyroid disease
IBD
IBS
when is endoscopy most appropriately used?
peristent and CHRONIC diarrhea
OR pts with significant lab abnormalities
when is 72 hr stool collection for fecal fat used?
only for chronic diarrhea
tenting of skin/decreased skin turgor
dehydration
NPO slows diarrhea some but not by much
suggests it’s secretory and NOT osmotic
