6.1 Diarrhoea: Causes and Consequences

Question 1

Timeframe of acute vs chronic diarrhoea

Answer 1

Acute: <4 weeks
Chronic: >4 weeks

Question 2

Define diarrhoea

Answer 2

More than 3 bowel motions per day, AND/OR loose motions.

Question 3

Of the 7 types of the bristol stool scale, which is the best? which is the hardest to pass, and which is the easiest?

Answer 3

• Type 4 (middle) is the “nirvana”
• Type 7 is water, and type 1 is separate, hard lumps (hardest)

Question 4

Osmotic vs secretory vs inflammatory vs altered motility diarrhoea

Answer 4

Osmotic: presence of non-absorbable contents in the gut lumen causes osmotic gradient that pulls water into intestine (improves with fasting)

Secretory: caused by active secretion of electrolytes and water into the small intestine (does not improve with fasting)

Inflammatory: damage to mucosal lining, allowing blood, mucus, and proteins to enter lumen. Leads to cytokine release, causing inflammation that increases secretion and decreases absorption (may contain blood and mucus)

Altered motility: increased intestinal motility decreases amount of time available for water and electrolyte absorption, leading to diarrhoea

Question 5

Explain 3 mechanisms of antibiotic related diarrhoea. What are the impacts on patient health, and how do we treat it?

Answer 5

Overlying mechanism is disruption of gut microbiota. Can cause:
1. Infection (e.g. C Diff): Inflammatory diarrhoea
2. Altered carb metabolism: osmotic diarrhoea
3. Direct effects on mucosa: secretory/altered motility diarrhoea

Impacts on health include dehydration, electrolyte imbalance, weight loss/malnutrition, fever/systemic inflammation (infection)

Question 6

What does foecal calprotectin assess?

Answer 6

Very sensitive assessment of inflammation of bowel.

Question 7

What are the three subtypes of IBS?

Answer 7

• IBS-D: Diarrhoea
• IBS-C: Constipation
• IBS-M: Mixed

Question 8

What is the main biomarker for IBS?

Answer 8

• There are none; it is a syndrome, a collection of symptoms
• We make the diagnosis based on symptoms alone

Question 9

What are the symptoms of IBS?

Answer 9

• Changes in bowel habits
• Abdominal pain influenced by defecation
• Bloating

Question 10

Crohn’s vs Ulcerative Colitis

Answer 10

Crohn’s can occur anywhere in the GIT, whereas ulcerative colitis only occurs in the large intestine (colon-itis)

Question 11

Mechanism/features of coeliac disease

Answer 11

Features: Diarrhoea/weight loss (kids), nutrient deficiency, bloating/diarrhoea

Mechanism: HLA-gluten complex recognised as foreign by T cells; autoimmune attack on the small bowel

Question 12

Mechanism/key features of IBD

Answer 12

Mechanism: autoimmune attack on colon (ulcerative colitis) or whole GIT (Crohn’s), causing ulcers

Key features include: diarrhoea, rectal bleeding, joint pain, osteoporosis, mouth ulcers (systemic inflammation)

Question 13

Diarrhoea red flags

Answer 13

• Passing blood
• Losing weight

(Makes sense; both could be associated w/ cancer)

Question 14

What is the point of a low FODMAP diet?

Answer 14

Removes carbohydrates that otherwise might be poorly absorbed, decreasing chances of osmotic diarrhoea