All things diarrhoea (but not malabsorption) Flashcards Preview

Gastroenterology > All things diarrhoea (but not malabsorption) > Flashcards

Flashcards in All things diarrhoea (but not malabsorption) Deck (18):
1

What is chronic diarrhoea?

Persistent diarrhoea for > 2 weeks

2

What are the different types of diarrhoea?

Secretory
- Due to damaged intestinal epithelial cells
- Mainly due to bacterial toxins
- Stimulates Cl secretion and inhibits neutral copied NaCl absorption
- >200ml/day
- Continues when enteral feeding is stopped
- Faecal Na > 90mosmol/L
- pH >6
- Reducing substances negative

Osmotic
- Presence of non-absorbed carbohydrate solutes gets fermented by colonic bacterial producing short-chain organic acids resulting in osmotic load
- Ceases when enteral feeding stopped
- Faecal pH < 5
- Faecal Na < 60mosmol/L
- Faecal osmo > 100 (290 - 2(Na+K)) - suggesting extra sugar load
- Reducing substances positive

3

What is the acid-base disorder related to vomiting, esp with pyloric stenosis ?

Metabolic alkalosis with hypochloraemia and hypokalaemia

Gastric fluid
- main cation at rest: Na+
- main cation when stimulated: H+
- main anion: chloride

Loss of gastric fluid
- results in chloride and variable H+ loses
- causes metabolic alkalosis, initiated by loss of H+ then sustained by disproportionate loss of Cl- and the kidneys tried to reabsorb an anion (choosing HCO3)
- Loss of ECF --> activates renin-aldosterone system --> retains Na in exchange for K

4

What is the acid-base disorder related to diarrhoea?

Only occurs when volume of fluid lost is large requiring the kidney's ability to adjust excretion....

Typical presentation:
- Hypotension, acute renal failure
- Metabolic acidosis with hyperchloraemia and hypokalaemia

Long term laxative ingestion results in chronic loss of potassium so kidneys try to increase absorption of K in exchange of H+ --> metabolic alkalosis

5

What are the differential diagnoses for acute diarrhoea?

Systemic infections:
- UTI, pneumonia, OM, meningitis, sepsis
Surgical
- Appendicitis, intussusception, malrotation, Hirschprung's enterocolitis, partial bowel obstruction
Other
- DM, antibiotic-associated diarrhoea, primary disaccharide deficiency

6

What are common causes of diarrhoea?

Viral
- rotavirus (winter) (dsRNA)
- norovirus (all seasons) (ssRNA)
- adenovirus 40, 41 (summer)
- astrovirus (winter)

Bacterial
- Campylobacter
Salmonella
EPEC / EAEC / EHEC

Protozoa
- Giardia
- Cryptosporidium

7

What is lactase deficiency a complication of gastroenteritis?

Destruction of epithelial cells --> subvillous atrophy --> brush border enzymes deficiency (lactase is most superficial)

8

What kinda vaccine is the rotateq?

Live attenuated vaccine
- reduces gastro of any severity by 70%
- reduces severe gastro by 85-100%
- reduces host by 50%

9

What are complications of viral gastroenteritis?

Dehydration
Febrile convulsions (rotavirus)
Seizures from electrolyte imbalance
Lactose intolerance
- lasts 6-8wks

10

Why do you need 1:1 sodium: glucose solution for rehydration?

Absorption of glucose is via glu-Na cotransporter....

11

What are the causes of inflammatory enteritis?

Presents as fever, abode pain, abrupt onset of diarrhoea before vomiting, bloody / mucousy stools

Shigella, E.coli, Salmonella, Campylobacter, C.diff, entamoeba histolytic

12

What are causes of secretory (enterotoxigenic) diarrhoea?

Stools are watery with no faecal leucocytes.

Toxigenic
- S aureus, B cereus, C perfringens

Enterotoxigenic
- E.Coli, giardia, cryptosporidium, rotavirus, norovirus

13

What are the complications of shigella enteritis?

Gram -ve rod

Dehydration
Untreated illness is ~ 2 weeks
Abx can reduce course of illness / duration of pathogen excretion
Isolate untile diarrhoea settles

Rare
- Headache / meningism / seizures / encephalopathy
- HUS
- Septicaemia <5%
- Reiter syndrome (arthritis / urethritis / conjunctivitis)
- Hepatitis

14

What are the special features that causes complications related to Salmonella infection?

Gram negative rod (bacilli) of the enterobacteriaceae family

Produces cholera-like endotoxin --> secretory diarrhoea
Also invades mucosa --> inflammatory response

Survives poorly in low pH conditions --> increased in those on PPI

Has special virulence factors to invade blood stream resulting in 1-5% bacteraemia
Risk factors: immunodeficiency (HIV: 50% mortality), < 3m old, sickle cell disease, IBD, malaria, schistosomiasis

Extra-intestinal disease
- Osteomyelitis
- Meningitis and brain abscess
- Endocarditis
- Reactive arthritis (HLAB27)

Cotrimoxazole / 3rd generation cephalosporin only indicated for <3/12, disseminated infection / severe or protracted course
(abx doesn't shorten clinical course, in fact, may actually increase excretion time)

15

What are the complications of campylobacter?

Gram -ve rod
9 species assoc with human disease - C. jejuni most common

Complications
- reactive arthritis (large migratory arthritis 5-40 days post)
- Guillain Barre syndrome (accounts for 25-40%)
- Reiters
- Ig A nephropathy

Antibiotics not beneficial...

16

What are the complications with yersinia?

Gram negative coccobacilli

Siderophoric (iron loving)
Can present like appendicitis

17

What are the complications with C.diff?

Spore-forming gram positive anaerobic rod (lives in soil)

Spectrum of severity
- from mild self-limited diarrhoea to pseudomembranitis colitis

Treatment
- Discontinue current abx
- rehydration
- Metronidazole or vancomycin

18

Who is the mimic of coeliac disease?

Giardia
- protozoa (flagellate)
- lives in duodenum and upper jejunum
- causes symptoms of bloating / flatulence / intermittent diarrhoea / constipation / FTT / abdominal pain and cramps
- causes partial villous atrophy
- also releases cysts (faecal sample)
- treat with metronidazole