Pathophys of Diarrhea

Question 1

T or F: Daily ingestion makes up the majority of liters that enter the gut everyday.

Answer 1

False, 6.5 Ls come from the saliva, gastric secretions, bile, pancreatic secretions, and small intestinal secretions. Only 2L from ingestion

Question 2

Where is the majority of fluid absorbed?

Answer 2

Small Intestines

Question 3

In the small intestine, what transports (2) are the main stimulus for water reabsorption?

Answer 3

Na/glucose co transporter and Na/H exchanger

because Na is the main factor for water reabso

Question 4

In the large intestinal crypts, what transporter is the main one associated with water reabso?

Answer 4

epithelial Na channel ENaC

Question 5

What are pathophysiologic mechanisms of increased intraluminal fluid?

Answer 5

decreased absorption (osmotic mech)
increased secretion (secretory)
inflammation

Question 6

What are some causes of osmotic diarrhea?

Answer 6

lactose, sorbitol and mannitol, lactulose (a rx for hepatic encephalopathy)

Mg compounds, Golyetly, fleets phosphosoda prep

Question 7

What is the one key to secretory diarrhea?

Answer 7

excessive Cl secretion into the gut

Question 8

What is the mechanism of cholera?

Answer 8

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

Question 9

Why is CF still around?

Answer 9

May provide a selective advantage over cholera because that channel responsible for cholera isn’t present as a functional channel

Question 10

The oral rehydration formula for cholera takes advantage of what channel on the enterocyte?

Answer 10

na glucose co transporter. it’s a glucose high salt drink

Question 11

What are causes of secretory diarrhea?

Answer 11

cholera, e.coli, yersinia
dulcolax
cholinergics, prostaglandins
bile, arsenic, caffeine, etoh
neuroendocrine tumors (VIPoma, medullary carcinoma of thyroid)

Question 12

What are clinical fts of osmotic diarrhea?

Answer 12

moderate volume, resolves with fasting, flatulence, stool ph less that5.3, osmolar gap over 125

Question 13

what are clinical fts of secretory diarrhea?

Answer 13

voluminous, watery, persists with fasting, no flatulence, stool ph 6-7, osmolar gap less than 50

Question 14

Should stool osmolarity be the same as serum osm?

Answer 14

yes

Question 15

What is the inflammatory mechanism for diarrhea of parasites, food allergies and celiac sprue?

Answer 15

mast cells

Question 16

what is the inflammatory mech for diarrhea of salmonella and whipples ibd

Answer 16

phagocytes, macrophages, neutrophils, eosinophils

Question 17

inflamm mech for diarrhea of gvh?

Answer 17

t-lymphocytes

Question 18

inflamma mech for diarrhea of shigella and rotavirus?

Answer 18

direct toxins

Question 19

Clinical approach to acute diarrhea

Answer 19

less than 3 weeks
infectious
secretory or inflammatory
self-limited
tx - mostly supportive

Question 20

What is the cause of infxs diarrhea associated with aids?

Answer 20

cryptosporidium

Question 21

With pseudomembranous colitis, what do you see on histology?

Answer 21

fibrin, neutrophils, volcano-like, somewhat bloody

Question 22

medical management of acute diarrhea is based on what major factor?

Answer 22

if they are becoming dehydrated

Question 23

What are risk factors for c. difficile?

Answer 23

antibiotic usage, extremes of age, hospitalization

Question 24

How do you dx c. difficile infxn/

Answer 24

pseudomembraneous colitis on endoscopy, stool assay

Question 25

What are etiologies of chronic diarrhea?

Answer 25

infectious, immune-mediated, malabsorption

osmotic, secretory or inflammatory

Question 26

Chronic diarrhea iwth no mucosal injury is likely what sort of things?

Answer 26

maldigestion malabsorption ie lactase deficiency pancreatic insufficiency

hypermotility

neuroendocrine malginancies ie vipoma

factitious - laxative

Question 27

What are clinical features of lactase deficiency?

Answer 27

flatulence
osmotic diarrhea
acidic stool pH

Question 28

How do you tx IBS?

Answer 28

anti-cholinergics

5-ht receptor antagonists

Question 29

CHronic diarrhea with mucosal injury is like associated with what sorts of things?

Answer 29

chronic infxns ie hiv parasites
allergies/immune mediated
malginancies

Question 30

When do you see loose granulomas?

Answer 30

Crohns dz (minority of pts)

Question 31

What are two types of microscopic colitis?

Answer 31

lymphocytic and collagenous

Question 32

What do you see on histo in collagenous colitis?

Answer 32

a very thickened bm

Question 33

What is behcet’s dz?

Answer 33

a generalized vasculitis, oral and genital aphthous ulcers, uveitis, GI tract ulcers, non-erosive arthirits (RAAAAARRRRREEE DZ)

Question 34

What are the red flags associated with chronic diarrhea pts?

Answer 34

unintentional weight loss
nocturnal diarrhea
signs of malnutrion
rectal bleeding

Question 35

what are things causing when red flegs are absent and labs are normal

Answer 35

lactose intolerance, bacterial overgrowth IBS, medication induced

Question 36

when red flags are present and labs are abnormal?

Answer 36

ibd, hyperthyroidism, infection, malabsorption, malignancy