8. Diaorrhea

Question 1

What is chronic diarrhoea?

Answer 1

4 or more stools per day for 4 weeks

Question 2

What causes diarrhoea?

Answer 2

Motility disturbance- IBD, Toddlers diarrhoea

Active secretion- acute infective diarrhoea, IBD

Malabsorption of nutrients- food allergy, coeliac disease, cystic fibrosis

Question 3

What causes osmotic diarrhoea

Answer 3

Movement of water into the bowel to equilibrate the osmotic gradient

usually caused by absorption (enzymatic defect, transport defect)

Mechanism of action of lactulose/movicol

Generally accompanied by macro and microscopic intestinal injury

Question 4

What causes secretory diarrhoea?

Answer 4

Secretory pathogens e.g. vibrio cholerae and enterotoxic e.choli care causative organisms

Intestinal fluid secretion predominately driven by active CL- secretion via CFTR

Question 5

What causes motility diarrhoea?

Answer 5

Pretty straightforward, classically toddler’s diarrhoea (chronic non-specific diarrhoea of toddler’s, still gain weight)

Can also be IBS, Congenital hyperthyroidism, chronic intestinal pseudo-obstruction

Question 6

How does inflammation cause diarrhoea

Answer 6

It is a mixed bag
May be malabsorption due to intestinal damage
Secretory effects of cytokines
Accelerated transit time in response to inflammation
Protein exudate across inflamed epithelium

Question 7

What is yiu approach to assess diarrhoea ?

Answer 7

History- age, abrupt/gradual, FH- nocturnal defacation- NOT good

Consider growth ad weight

Faeces analysis- appearance, stool culture, determination of secretory vs osmotic

Question 8

What beside test can you do for osmotic vs secretory diarrhoea?

Answer 8

Stop the feed. If improves osmotic, if does not secretory

Question 9

What tests do you do to differentiate between conditions?

Answer 9

Stool volume Small generally <200ml in 24 hours (osmotic)
Response to fasting (stop in osmotic not in secretory)
Stool electrolytes Osmotic Secretory
(Na) <70mmol/L >70mmol/L
(K) <30mmol/L >40mmol/L
(Cl) <35mmol/L >40 mmol/L

Question 10

What are some differentials for diarrhoea?

Answer 10

Fat malabsorption

Pancreatic Disease (diarrhoea due to lack of lipase and resultant steatorrhea)
Clasically cycstic fibrosis

Hepatobiliary disease
Chronic liver disease
Cholestasis

Question 11

What genes make yiu susceptible to coeliac disease?

Answer 11

HLA, DQ2, DQ8

Question 12

Explain ceoliac disease?

Answer 12

Autoimmune condition

Produces antibodies to gluten (found in wheat, barley and rye)

Question 13

What are the presentations of coeliac disease?

Answer 13

Abdo bloating
Diarrhoea
Failure to thrive 
Short stature
Constipation
Tiredness
Dermatitis

Question 14

What screening tests can you do for coeliacs disease

Answer 14

Anti- tissue transglutaminasel
Anti-endomysial
Anti-gliadin Concurrent IgA deficiency in 2% may result in false negatives
Gold standard-  duodenal biopsy 
Genetic testing- HLA DQ2, DQ8

Question 15

How does coeliac disease presents on endoscopy ?

Answer 15

Duodenal scalloping

Question 16

How does coeliac disease present on histiology?

Answer 16

Lymphocytic infiltration of surface epithelium, partial/total villous atrophy crypt hyperplasia

Question 17

What are the diagnostic criteria for diagnosing coeliacs disease without endoscopy

Answer 17

need all of the following:

Sympomatic children
Anti-TTG >10 times upper limit of normal
Positive anti-endomysial antibodies
HLA DQ2 DQ8 positive

Question 18

What is key to remember before diagnosis?

Answer 18

Serological and histological features will resolve if gluten is removed before testing