Malabsorption

Question 1

Two substances preferentially absorbed by the distal small intestine?

Answer 1

Bile salts and B12

Question 2

Two phases of intestinal absorption?

Answer 2

• Luminal - Alteration of physicochemical state of nutrients, so that they can be taken up by absorptive cells
• Intestinal - Processes occurring in cells and transport chennels of the intestinal wall

Question 3

What processes occur in the luminal phase of digestion?

Answer 3

Pancreatic enzyme degradation and bile acid complexation

Question 4

What determines bile quantity and quality?

Answer 4

1. Adequate liver function
2. Unobstructed bile flow
3. Intact enterohepatic bile salt circulation

Question 5

What is a frequent cause of luminal phase malabsorption?

Answer 5

Insufficient bile acids

Question 6

Causes of luminal malabsorption?

Answer 6

• Iterruption of the normal continuity of the ddistal stomach and duodenum
• Pancreatic dysfn
• Deficient/ineffective bile salts due to: Impaired excretion of the bile, bacterial overgrowth, deficient bile salts

Question 7

What does intestinal-phase malabsorption frequently reflect?

Answer 7

Specific enzyme defects

Question 8

What do defects in microvilli often result in?

Answer 8

Malabsorption of sugars (ie primary disaccharidase deficiencies)

Question 9

What is short bowel syndrome?

Answer 9

Malabsorption due to resection of the small bowel

Question 10

A disorder in which absorptive cells cannot synthesize the apoprotein required for the assembly of lipproteins and chylomicrons?

Answer 10

Abetalipoproteinemia

Question 11

Lactose tolerance test?

Answer 11

Measuring blood sugar after ingestion of a standard amount of disaccharide

Question 12

Isotopically labeled vit B12 given orally and its blood level then determined?

Answer 12

Schilling test

Question 13

Typical deficiency seen in generalized malabsorption?

Answer 13

Typically always impaired absorption of dietary fat

Question 14

Describe the D-xylose absorption test

Answer 14

D-xylose does not require any component of the intestinal phase to be absorbed, so this test is used to evaluate the luminal phase of absorption

Question 15

Utility of the 14CO2-cholyl-glycine breath test?

Answer 15

Measured in exhaled air after oral admin is a test of bile salt abs in the ileum

Question 16

What causes intolerance to milk products?

Answer 16

Lactase deficiency

Question 17

Characteristics of Celiac Disease?

Answer 17

1. Generalized malabsorption
2. Small intestinal mucosal lesions
3. Prompt clinical and histopathological response to withdrawal of gluten-containing foods from diet

Question 18

Crucial risk factors for celiacs?

Answer 18

• Genetic predisposition
• Gliandin

Question 19

What are the compoents of grains that exacerbate celiac disease?

Answer 19

Gluten and gliandin

Question 20

Relationship of adenovirus to celiac disease manifestation?

Answer 20

Adenovirus codes an AA that has homology to alpha-gliadin.

Question 21

Histocompatibility complexes associated with celiac disease?

Answer 21

HLAB8, DR8, DQ2

Question 22

What skin disease is associated with celiac disease?

Answer 22

Celiac herpetiformis

Question 23

What are the characterisitcs of fully developed celiac disease?

Answer 23

• Blunting/total disappearance of villi
• Damaged mucosal surface epithelial cells with numerous intraepithelial lymphocytes
• Increased plasma cells in the lamina propria but not in the deep layers

Question 24

Number one characteristic of celiac disease?

Answer 24

Generalized malabsorption

Question 25

Tests used to ID celiac disease?

Answer 25

* IgA antiendomysial Ab * antitissue transglutaminase Ab

Question 26

Number one Tx to lead to complete and prolonged clinical/histopathologic remission?

Answer 26

* Strict gluten free diet

Question 27

Probable cause of refractory sprue?

Answer 27

Monoclonal T-cell proliferation

Question 28

Syndrome that autoimmune enteropathy is found?

Answer 28

IPEX syndrome * X-linked * Immunodysregulation * Polyendocrinopathy * enteropathy Due to FoxP3 mutation

Question 29

What is Whipple disease?

Answer 29

Small bowel filled with macrophages packed with small rod-shaped bacteria

Question 30

Bug that causes Whipple Disease?

Answer 30

Tropheryma whippelii

Question 31

Probable pathogenesis of Whipple Disease?

Answer 31

Impaired ability to degrade intracellular microorganisms; Circulating cells expressing CD11b are **reduced**. CD11b is used to activate macrophages.

Question 32

What does abetalipoproteinemia involve?

Answer 32

Failure to make apoprotein B

Question 33

What is apoprotein B typically used for?

Answer 33

Chylomicrons do not assemble and lipids cannot be transported out of cells

Question 34

What does abetalipoproteinemia lead to?

Answer 34

Acanthocytosis in erythrocytes and selective demyelinization

Question 35

Absorption of what vitamins are impaired in abetalipoproteinemia?

Answer 35

ADEK

Question 36

Lymphangiectasia and peripheral lymphedema?

Answer 36

Milroy disease

Question 37

What is lymphangiectasia?

Answer 37

Pathologic dilation of lymph vessels

Question 38

Cause of tropical sprue?

Answer 38

Etiology unknown, some studies suggest long-term contamination of the bowel with bacteria

Question 39

What does tropical sprue cause?

Answer 39

Folate deficiency