GIT

Question 1

Define acute diarrhea

Answer 1

Passage ≥ 3 loose stools per day for <2 weeks

Question 2

Define chronic diarrhea

Answer 2

> 4 weeks

Question 3

Name 3 indications for lab evaluation of diarrhoea.

Answer 3

• Severe with fever
• prolonged >14 days
• dysentery - contain blood / mucus

Question 4

Which investigations are done for chronic secretory diarrhoea (5)

Answer 4

Exclude bacterial/parasitic infection
• gastrin
• metanephrine
• tsh
• test for bacterial overgrowth only inselected patients

Question 5

Which investigations are done for chronic osmotic diarrhoea (3)

Answer 5

• Usually without steatorrhea due to poorly absorbable CHO or mg salts
• Suspected lactose intolerance: hydrogen breath test / measure lactose in mucosal biopsy
• sorbitol or fructose ingestion

Question 6

Name 7 malabsorption causes of diarrhoea, steatorrhea

Answer 6

•Pancreatic enzyme deficiency eg chronic pancreatitis, cystic fibrosis
• bile salts deficiency biliary obstruction and hepatic disease
• coeliac disease
. IBD
• drugs: laxatives, magnesium salts
• Endocrine: thyrotoxicosis, carcinoid syndrome, vipoma
• lactase deficiency - lactose intolerance

Question 7

Name 3 lab tests for chronic diarrhoea

Answer 7

• Faecal na, k to calculate osmotic gap
>125 = osmotic diarrhoea
<50 = secretory diarrhoea

• faecal ph
< 5,6 = carbohydrate malabsorption

• faecal laxative screening: magnesium, phenolphthalein

Question 8

How calculate osmotic gap

Answer 8

290 - 2 (na +k)

Question 9

How further evaluate chronic inflammatory diarrhoea? (2)

Answer 9

• Small bowel follow through and sigmoidoscopy or colonoscopy with biopsies for IBD
• stool culture, ID infectious causes inflammation

Question 10

How further evaluate chronic fatty diarrhoea? (2)

Answer 10

• Assess pancreatic exocrine function by fecal elastase! (Good sensitivity,)
• small bowel biopsy and aspirate of contents for culture

Question 11

How further evaluate carbohydrate malabsorption diarrhoea? (2)

Answer 11

• Hydrogen breath tests (measured in exhale while fasting and after sugar - bacterial overgrowth, carbohydrate malabsorption)
• d-xylose absorption test (differentiate between mucosal disease which will have decreased absorption, and pancreatic disease)

Question 12

How diagnose h pylori?

Answer 12

Urea breath test best.
(Can also do stool antigen by immunoassay)

Question 13

What is zollinger Ellison syndrome

Answer 13

Gastrinoma → increased acid secretion
20% also have parathyroid and pituitary adenoma as part of
Men 1

Question 14

Diagnosis zollinger Ellison syndrome

Answer 14

• Raised basal acid output (bao)>15 and raised serum gastrin

• exclude h pylori and pernicious anaemia, they also cause high gastrin

Question 15

What is coeliac disease

Answer 15

Sensitive to gliadin in gluten

Question 16

Diagnosis coeliac disease? (4)

Answer 16

• Serology while on gluten diet
. Antibodies: IgA ema (endomysial antibody), IgA tTG (tissue transglutaminase antibody)
. In selective IgA deficiency, do igG ttg or EMA
• At least 3 duodenal biopsies to confirm diagnosis

Question 17

IBD diagnosis? (2)

Answer 17

• Fecal calprotectin!
• fecal alpha 1 antitrypsin

Question 18

Define secretory diarrhea and examples

Answer 18

• Luminal ion channels disrupted → increased secretion or decreased absorption of ions. → water follows ions.
• No structural damage
• example: mostly infections. cholera → Cl secretion → sodium and water follows; rotavirus; C diff; carcinoid; gastronoma; VIP Oma

Question 19

Define osmotic diarrhea and examples

Answer 19

• Aka malabsorption.
• increased osmole eg sugar, salt, fat, artificial sweetener draws too much water into bowels
• eg lactase deficiency, celiac/tropical sprue, Whipple’s disease, pancreatic insufficiency, consuming sugar free food drink/gum

Question 20

Define inflammatory diarrhea and examples

Answer 20

Damage to mucosal lining and /or brush border
(Exudative = oozing blood, mucous, pus, plasma protein into stool)
Eg: IBD, some infections, ischaemic colitis, diverticulitis, radiation colitis

Question 21

How diagnose secretary diarrhea

Answer 21

• Fecal Osmolar gap < 50
• no fecal fat. No stool. No fat /blood/wbc

Question 22

How diagnose osmotic diarrhea (2)

Answer 22

• Stool osmolar gap > 125
• goes away with npo
• can have faecal fat

Question 23

How diagnose inflammatory diarrhea (4)

Answer 23

• Blood
• WBC
• mucous in stool
• do colonoscopy

Question 24

What is calprotectin and what does it indicate

Answer 24

• Ca binding protein found in cytosol of neutrophils
• resistant to bacterial degradation, stable in stool for 5 days following excretion
• thus raised calprotectin = increased neutrophils in git = indicates inflammation
• Do colonoscopy for these patients - likely IBD (not ibs- this is how differentiate )