Diseases of the small bowel

Question 1

4 types of diarrhea

Answer 1

watery, steatorrhea, inflammatory/exudative, functional (IBS)

Question 2

produced by osmotic gradient change or excessive secretion

Answer 2

watery diarrhea

Question 3

stool osmotic gap equation

Answer 3

stool osm gap = 290 - 2(stool Na + stool K)

greater than 50 mOsm = osmotic diarrhea

Less than 50 mOsm = secretory diarrhea

Question 4

Some causes of osmotic diarrhea

Answer 4

lactose intolerance, sorbitol, fructose, Mg-containing laxatives

Question 5

Some causes of secretory diarrhea

Answer 5

Bacterial toxins (cholera), neuronendocrine tumors (gastrinoma), bile salt, stimulant laxatives, motility disorders (diabetes, IBS)

Question 6

diarrhea that is fecal fat +

Answer 6

steatorrhea

Question 7

Causes of steatorrhea

Answer 7

malabsorption (celiac, whipple’s disease, small bowel bacterial overgrowth, short gut from surgery) and maldigestion (pancreatic insufficiency, biliary obstruction)

Question 8

diarrhea that is often bloody

Answer 8

inflammatory/exudative diarrhea

Question 9

causes of inflammatory/exudative diarrhea

Answer 9

Crohn’s disease, ischemia, invasive infections (C diff, EHEC, Amebiasis, Shigella)

Question 10

usually watery diarrhea, diagnosis of exclusion

Answer 10

Irritable Bowel Syndrome

Question 11

Sx include weight loss, diarrhea, foul-smelling stools and vitamin deficiencies

Eg.: Steatorrhea

Answer 11

malabsorption

Question 12

Mechanism of pancreatic insufficiency leading to malabsorption

Answer 12

chronic pancreatitis –> pancreatic insufficiency

decreased typsinogen, chymotrypsinogen, proelastase and procarboxypeptidase –> protein malabsorption

decreased lipase and colipase –> lipid maldigestion –> lipid malabsorption

Question 13

Mechanism of liver disease leading to malabsorption

Answer 13

chronic liver disease (alcoholic cirrhosis, primary biliary cirrhosis, biliary obstruction) –> decreased bile formation –> decreased lipid absorption

Question 14

Mechanism of Small Intestinal Bacterial Overgrowth (SIBO) leading to malabsorption

Answer 14

stasis (scleroderma, diabetes), partial intestinal obstruction, small bowel diverticula and decreased gastric acid secretion –> bacterial overgrowth –> inactivated bile acids, catabolization of disaccharides, reduced effectiveness of enterokinase –> maldigestion –> eventual deficiency of fat-soluble vitamins A, D, E and B12

Question 15

differentiate SIBO from tropical sprue

Answer 15

SIBO –> bacterial production of folate; B12 malabsorption –> normal-high folate levels, low B12

tropical sprue –> B12 and folate deficiency

Question 16

Mechanism of malabsorption in small intestinal structural diseases

Answer 16

damaged mucosa –> decrease in absorptive surface area

Question 17

unexplained Fe deficiency anemia in adults.

intraepithelial lymphocytes –> loss of villi
Crypt hyperplasia -> malabsorption

+tTg (anti-tissue transglutaminase) IgA

Answer 17

Celiac sprue –> require gluten-free diet

Question 18

Complication of long-standing celiac disease

Answer 18

T-cell lymphoma

Question 19

residents/visitors of the tropics. Can occur years after returns from the tropics

patchy villus atrophy

megaloblastic anemia (folate and B12 deficiency) with diarrhea

Answer 19

tropical sprue

Question 20

infection with G+ Tropheryma whippelii

GI sx, fever, joint pain, or neuro sx

small intestinal biopsy –> blunting, infiltration of lamina propria with large PAS+ staining macrophages filled with organism

Answer 20

Whipple’s disease

Question 21

treatment of Whipple’s disease

Answer 21

prolonged course of abx

Question 22

Areas supplied by superior mesenteric artery (SMA)

Answer 22

part of the duodenum, entire small intestine and half of the colon

Question 23

Areas supplied by the inferior mesenteric artery (IMA)

Answer 23

left colon and rectum

Question 24

collateral circulation betwen SMA and IMA

Answer 24

marginal arteries and Arc of Riolan

Question 25

occurs when 2/3 major intestinal arteries are occluded

Answer 25

chronic mesenteric ischemia

Question 26

most common small bowel malignancy

Answer 26

adenocarcinoma of the duodenum

Question 27

treatment of SIBO

Answer 27

antibiotics (ciprofloxacin)