Diarrhoea (Acute and Chronic)

Question 1

What is diarrhoea?

Answer 1

Clinical: Stools that are looser and/or more frequent than normal.
Physiological: stool >200gday, >3 mvts / day.

Question 2

How is diarrhoea classified?

Answer 2

• Acute v chronic
• Small v large volume
• Water (bowel disease) v. steatorrhoea
• Secretory v osmotic

Question 3

What does small volume diarrhoea indicate?

Answer 3

Tbsp of stool: typical of colonic diseases.

Question 4

What does large volume diarrhoea indicate?

Answer 4

> 1/2c stool; typical of small bowel diseases

Question 5

What is acute diarrhoea?

Answer 5

Passage of frequent, unformed stools

Question 6

What is the aetiology of acute diarrhoea?

Answer 6

• usually infectious

- most common self limiting and resolve

Question 7

RFx for acute diarrhoea?

Answer 7

• Food: seafood, chicken, eggs, beef
• Rx: ABx, laxatives
• Other: risky sexual behaviour, infectious outbreaks.

Question 8

Treatment acute diarrhoea?

Answer 8

-Fluid and electrolyte replacement PO (IV if severe)

Anti diarrhoeal and anti biotics rarely indicated.

Question 9

How does S. typhi present?

Answer 9

S. typhi:

• Rose spot rash: transient maculopapular rash on anterior thorax, upper abdo
• Prodrome: high fever, bradycardia, headache and abdo pain.

Question 10

What occurs in inflammatory diarrhoea?

Answer 10

Organsims and cytotoxins invade mucosa killing mucosal cells and further perpetuating the diarrhoea. Usually affects the colon.

Question 11

What are the infectious causes of inflammatory diarrhoea?

Answer 11

Your stool smells extremely crappy:

• Yersinia
• Shigella
• Salmonella
• EHEC, E. histolytica
• Campylobacter, C. difficile

Question 12

What is chronic diarrhoea?

Answer 12

Persists >4/52

Question 13

Ix in diarrhoea?

Answer 13

• Stool MCS
• Faecal electrolytes and osmolarity
• Faecal fat (presence FFAs/ neutral fat)
• Faecal elastase
• C. diff
• Faecal calprotectin
• Faecal laxative screen
• Faecal alpha 1 antitrypsin

Question 14

Why is faecal elastase tested in diarrheoa Ix?

Answer 14

Marker of pancreatic exocrine sufficiency

Question 15

What causes osmotic diarrhoea?

Answer 15

Presence of excess unabsorbed substrates in lumen. Common:

-FODMAP malabsorption

Question 16

Stool volume in osmotic diarrhoea?

Answer 16

Typically

Question 17

Stool osmotic gap in osmotic diarrhoea?

Answer 17

Increased (>100)

Question 18

Effect of fasting on osmotic diarrhoea?

Answer 18

Stops with fasting

Question 19

What causes secretory diarrhoea?

Answer 19

Active anion secretion from enterocytes. Common causes:

• bacterial toxins
• hormone secreting tumours (e.g. carcinoid, gastrinomas)
• laxative abuse
• hyperthyroidism

Question 20

Stool volume secretory diarrheoa?

Answer 20

> 1L/d; watery.

Question 21

Stool osmotic gap secretory diarrhoea?

Answer 21

Normal osmolality (osmolar gap

Question 22

Effect of fasting on secretory diarrhoea?

Answer 22

Diarrhoea persists during fasting.

Question 23

What causes inflammatory diarrhoea?

Answer 23

Altered membrane permeability (exudation of protein, blood, mucous).
Common:
-invasive bacteria 
-CMV colitis
-IBD

Question 24

Stool volume inflammatory diarrhoea?

Answer 24

Generally small.

Question 25

Stool leukocytes and RBCs?

Answer 25

Increased RBCs and WBCs. May contain frank blood.

Question 26

Causes of rapid transit diarrhoea?

Answer 26

• IBS
• thyrotoxicosis
• diabetic neuropathy

Question 27

Mechanisms and causes of slow transit diarrhoea?

Answer 27

Bacterial overgrowth -> bile salt inactivation.

-Intestinal stasis due to anatomical defects (strictures, blind loops, surgical procedures).