Malabsorption: Ray

Question 1

Describe the three steps to normal nutrient absorption.

Answer 1

1) Lumenal and brush border processing
2) Absorption into the intestinal mucosa
3) Transport into the circulation

Question 2

Discuss the difference between global and partial malabsorption and the clinical implications of each.

Answer 2

Global- results from reduced mucosal involvement or reduced absorptive surface. Global deficiency of nutrients.

Partial- only part of the bowel has malabsorptive properties, so certain nutrients will not be absorbed while others are, based on their geographic pattern of absorption. Ex: B12 in the ileum

Question 3

Describe gastric causes of malabsorption.

Answer 3

atrophic gastritis
autoimmune gastritis
gastric resection

Question 4

Describe pancreatic causes of malabsorption.

Answer 4

Congenital enzyme deficiency
Pancreatic insufficiency (chronic pancreatitis, CF)

Question 5

Describe liver and biliary causes of malabsorption.

Answer 5

Inborn errors of bile transport
Cirrhosis
Biliary tumors
Primary and secondary sclerosing cholangitis

Question 6

Describe lymphatic disease causes of malabsorption.

Answer 6

Primary intestinal lymphangectasia

Secondary: lymphoma, solid tumors, thoracic duct trauma or obstruction

Question 7

Describe intestinal causes of malabsorption.

Answer 7

Amyloidosis
Celiac dz
Crohn's dz
Food allergies
Graft vs. host dz
Intestinal infections
Radiation enteritis
Tropical sprue
Others...

Question 8

Describe neuroendocrine causes of malabsorption.

Answer 8

Carcinoid syndrome
Glucagonoma
Z-E syndrome
Somatostatinoma

Question 9

Describe endocrine causes of malabsorption.

Answer 9

Diabetes
Addison’s dz
Hypothyroidism

Question 10

Describe systemic causes of malabsorption.

Answer 10

Scleroderma
Lupus
Neurofibromatosis

Question 11

Malabsorption of ______ is the most commonly used indicator of global malabsorption.

Answer 11

fat

Question 12

In healthy people, stool fat excretion is usually less than ___ grams/day.

Answer 12

6 grams/day

Question 13

Steatorrhea is dx’d when stool fat is > ____g/day.

Answer 13

20g/day

Question 14

Describe the qualitative test for excess fat in stool.

Answer 14

Sudan stain for fat globules has a 90% sensitivity

Question 15

Describe the tests for evaluating CHO malabsorption.

Answer 15

Can rely on fermentation of undigested CHO by intestinal bacteria.
Direct measurement of the absorption of specific nutrients after a test dose.

Question 16

Celiac sprue:
Etiology
Intolerance to?
Global or partial malabsorption?
Symptoms?
Dx?
Histology?

Answer 16

Etiology: Autoimmune disorder of small bowel
Intolerance to: gluten
Global malabsorption
Symptoms: range from mimicking IBS to peds pt w/ poor growth/failure to thrive.
Dx: blood test for tissue transglutaminase (tTG) (will be elevated). Test total IgA (deficient). tTG:IgA will be elevated. Small bowel biopsy. Pt needs to be on gluten diet for tests to be revealing. Need to be HLA-2 or HLA-8 positive.
Histo: intraepithelial lymphocytosis (CD8+) at tips of villi. Crypt hyperplasia. Villous atrophy.

Question 17

Describe dz associations of Celiac dz/sprue?

Answer 17

Dermatitis herpetiformis (subepithelial clefts w/ neutrophilic infiltrate)
Enteropathy assoc. T-cell lymphoma. Seen as sheets of lymphocytes "eating up glands".

Question 18

Describe the symptoms of lactose intolerance.

These pts are highly susceptible to _______ loss.

Answer 18

Bloating, flatulence, abd. pain, diarrhea, after ingesting dairy.
Highly susceptible to bone loss because of lack of Ca++ in diet.

Question 19

Describe dx of lactose intolerance.

Answer 19

History
Lactose Hydrogen breath test- measured Q30mins x3hrs after baseline 25g lactose. >20ppm = LI
Lactose tolerance test- Give 50g lactose, measure blood glucose (should rise >20mg/dl w/o symptoms) not used

Question 20

Excessive growth of bacteria in the small bowel can result in:

Answer 20

FIM: fermentation, inflammation, malabsorption

Question 21

How can you dx small bowel bacterial overgrowth?

How do you tx it?

Answer 21

Dx with:
Hx
Empiric trial of Abx
CHO breathe tests

Tx with:
Rifaxamin x7-10days. Not absorbed. Lasting results.
Treat underlying disorder (motility disorder, surgical correction of anatomical defect)

Question 22

MC symptoms of chronic pancreatitis:

Answer 22

Abd. pain

Pancreatic insufficiency- Fat malabsorption, diabetes. Does not occur until 90% of function is lost.

Question 23

What is going on in Whipple’s dz?

Answer 23

Foamy macrophages filled w/ T. whippelii accumulate in small intestinal lamina propria resulting in lymphatic obstruction.
Malabsorptive diarrhea of Whipple dz due to impaired lymphatic transport.

Question 24

What organism stains positively on PAS/diastase stain that can make it difficult to differentiate it from T. whippelii?
What stain will help differentiate the two?

Answer 24

M. avium/intracellulare

Acid fast stain to differentiate (Mycobact. is pos.)

Question 25

What are the classic symptoms of Whipple dz?

Answer 25

Middle aged pt. 
Weight loss
Diarrhea
Abd. pain
*arthropathy* give away!