ClinMed- common disorders of intestinal malabsorption

Question 1

Common disorders of malabsorption (6)

Answer 1

1. Small intestinal bacterial overgrowth (SIBO)
2. Exocrine pancreatic insufficiency
3. Impaired bile acid synthesis or secretion
4. Lactose intolerance
5. leaky gut syndrome
6. celiac dz

Question 2

What 4 components are required for normal small bowel absorption

Answer 2

1. digestion of nutrients in lumen
2. appropriate absorptive surface of small intestine
3. functioning membrane transport systems
4. available epithelial absorptive enzymes

Question 3

SIBO

- def

Answer 3

abnormal colonization of the small bowel with colonic bacteria

Question 4

SIBO

- pathophysiology

Answer 4

• anatomic alterations of foregut promotes stasis of intestinal contents leads to overgrowth (small-bowel diverticulosis, surgical blind loops, postgastrectomy states, strictures)
• intestinal motility disorders (DM neuropathy, impaired bacterial clearance)
• Achlorhydria may cause bacterial overgrowth in elderly people (ex. PPI overuse)

Question 5

What 6 things do bacteria do in SIBO

Answer 5

1. Deconjugate bile salts = fat malabsorption = diarrhea
2. metabolize B12, preventing absorption in the ileum
3. bacterial proteases, glycosides, toxins damage the epithelium
4. bacteria inflame the mucosa = diarrhea
5. Consume nutrients = malabsorption
6. exert inhibitory effects on upper GI functions

Question 6

SIBO

- clinical presentation

Answer 6

• weight loss or nutrient deficiencies
• abd discomfort
• diarrhea, steatorrhea
• bloating, excess flatulence

Question 7

SIBO

- dx

Answer 7

• breath H+ test: easiest

- quantitative culture of intestinal fluid aspirate via endoscopy: no need to do this, just breath test…

Question 8

SIBO

- tx

Answer 8

• 10-14 days abx, tetracycline, metronidazole best
• can be cyclic if sx recur
• low carb, high fat diet (bacteria metabolize carbs)
• correct nutritional deficiencies (esp B12)

Question 9

Exocrine pancreatic insufficiency (EPI)

- clinical sx

Answer 9

• steatorrhea
• diarrhea
• gas, flatulence
• weight loss
• bloating
• abd pain

Question 10

What percentage loss pancreatic secretory capacity must be loss to result in sx of EPI?

Answer 10

once capacity is <10% of normal

Question 11

Conditions associated with EPI

Answer 11

• CF
• chronic pancreatitis
• DM type I
• prior pancreatic sx
• pancreatic ca or blockage of pancreatic duct

Question 12

EPI

- dx

Answer 12

• qualitative fecal fat (easiest, always include in diarrhea wo)
• quantitative fecal fat (collect and keep stool for 72 hours)
• fecal elastase stool test (Roark never used)
• direct pancreatic stimulation test (not going to use in the real world)

Question 13

EPI

- Tx

Answer 13

• pancreatic enzyme supplementation - Creon & Zenpep (porcine-derived lipases, proteases, amylases)
• expensive
• Vitamin replacement ADEK

Question 14

Impaired Bile Acid Synthesis / Malabsorption

- common co-morbidity

Answer 14

IBS-D

• 10% of pts with IBS-D have severe bile acid malabsorption
• historically underestimated in IBS-D

Question 15

Impaired Bile Acid Synthesis / Malabsorption

- sx

Answer 15

• sudden onset, high volume, nocturnal diarrhea

- yellow discoloration of stool

Question 16

Impaired Bile Acid Synthesis / Malabsorption

- pathophysiology

Answer 16

• inadequate ileal reabsorption of bile acid

- excess bile acid reach colon leads to secretory diarrhea

Question 17

What percentage decrease of bile acid reabsorption must occur in the ileum to produce sx of Impaired Bile Acid Synthesis / Malabsorption??

Answer 17

5% decrease or less than 95% normal absorption

Question 18

Impaired Bile Acid Synthesis / Malabsorption

- what happens when bile acids reach colon

Answer 18

• increases gut permeability
• activates adenylate cyclase
• stimulates colonic secretion
• increases stool water and colonic motility

Question 19

Impaired Bile Acid Synthesis / Malabsorption

- feedback loop

Answer 19

• decreased circulating fibroblast growth factor 19 (FGF19) leads to excessive bile acid synthesis
• loss of feedback inhibition
• last thing pt needs is MORE bile acids

Question 20

Impaired Bile Acid Synthesis / Malabsorption

- what condition can precede

Answer 20

• acute ileitis
• Salmonella spp. or C. jejuni gastroenteritis
• “an insult” to the ileum

Question 21

Impaired Bile Acid Synthesis / Malabsorption

- what sx does it commonly follow

Answer 21

• cholecystectomy
• liver dumps bile acids into digestive tract, can send more than ileum is able to reabsorb
• body will often adjust over time and sx will stop

Question 22

Impaired Bile Acid Synthesis / Malabsorption

- treatment

Answer 22

• Bile salt-binding sequestrants (cholestyramine, colestipol, colesevelam)

Question 23

Impaired Bile Acid Synthesis / Malabsorption

- bile salt-binding sequestrant effects on sx

Answer 23

Decrease diarrhea caused by excess fecal bile acids

Question 24

Impaired Bile Acid Synthesis / Malabsorption

- how to take bile salt-binding sequestrant

Answer 24

• 1-3 times before meals

- do not take cholestyramine and colestipol with other drugs, take at least 2 hours before/after

Question 25

Impaired Bile Acid Synthesis / Malabsorption | - bile salt-binding sequestrant ADR

Answer 25

- bloating - flatulence - constipation - fecal impaction

Question 26

Lactose intolerance | - list three types

Answer 26

1. Primary Lactase deficiency 2. secondary lactase deficiency 3. Acquired lactase deficiency

Question 27

Primary lactase deficiency

Answer 27

- very rare - inherited deficiency/absence of lactase - autosomal recessive - babies require special formula with diff sugar such as sucrose

Question 28

Secondary lactase deficiency

Answer 28

- temporary, often caused by infection - ex. Rotavirus and Giardia, Celiac and Crohn's - damage to small intestine lining - Tx of infection heals lining - LTI resolves within 3-4 weeks

Question 29

Acquired lactase deficiency

Answer 29

- very common - 50% US adults - normal decline in lactase as age

Question 30

Lactose intolerance | - etiology

Answer 30

- lactose is not digested in SI and passes whole into colon - colon bacteria digest lactose - bacteria produce CO2, H+ gases

Question 31

Lactose intolerance | - sx

Answer 31

- abd distention and pain - excess burping - loud bowel sounds - gas and diarrhea following ingestion lactose - watery, explosive BM - stool urgency

Question 32

Lactose Intolerance | - dx

Answer 32

- H+ breath test (if need to prove, most pts know they have it... and don't want to ingest equivalent of a quart of milk!!) - pt can't tolerate breath test, treat for 2-4 weeks and reassess

Question 33

Leaky gut syndrome

Answer 33

- limited EBM - intestinal inflammation = disruption gut barrier - major determinant of rate of permeability is opening/closure of tight junctions between enterocytes

Question 34

Leaky gut syndrome | - causes of inflammation

Answer 34

- parasites - candida overgrowth - other pathogens - NSAIDS - alcohol - aspirin - foods containing lectins punch holes in cell membranes

Question 35

Leaky gut syndrome - common co-morbidity - genetics

Answer 35

- increased permeability in most Crohn's dz pts (worse if also take ASA) - also seen in 10-20% of Crohn's dz patients healthy relatives

Question 36

Leaky gut syndrome | - two other (not Crohn's) co-morbidities

Answer 36

- celiac - NSAIDs *not sure if it is people who have celiac and take NSAIDS or if it is celiac dz and NSAID use...

Question 37

Celiac Dz | - overview

Answer 37

- gluten-sensitive enteropathy - aka Celiac Sprue - intolerance to gluten (wheat, rye, barley, other grain) - injures/inflames mucosa