Diarrhoea (Acute and Chronic) Flashcards
What is diarrhoea?
Clinical: Stools that are looser and/or more frequent than normal.
Physiological: stool >200gday, >3 mvts / day.
How is diarrhoea classified?
- Acute v chronic
- Small v large volume
- Water (bowel disease) v. steatorrhoea
- Secretory v osmotic
What does small volume diarrhoea indicate?
Tbsp of stool: typical of colonic diseases.
What does large volume diarrhoea indicate?
> 1/2c stool; typical of small bowel diseases
What is acute diarrhoea?
Passage of frequent, unformed stools
What is the aetiology of acute diarrhoea?
- usually infectious
- most common self limiting and resolve
RFx for acute diarrhoea?
- Food: seafood, chicken, eggs, beef
- Rx: ABx, laxatives
- Other: risky sexual behaviour, infectious outbreaks.
Treatment acute diarrhoea?
-Fluid and electrolyte replacement PO (IV if severe)
Anti diarrhoeal and anti biotics rarely indicated.
How does S. typhi present?
S. typhi:
- Rose spot rash: transient maculopapular rash on anterior thorax, upper abdo
- Prodrome: high fever, bradycardia, headache and abdo pain.
What occurs in inflammatory diarrhoea?
Organsims and cytotoxins invade mucosa killing mucosal cells and further perpetuating the diarrhoea. Usually affects the colon.
What are the infectious causes of inflammatory diarrhoea?
Your stool smells extremely crappy:
- Yersinia
- Shigella
- Salmonella
- EHEC, E. histolytica
- Campylobacter, C. difficile
What is chronic diarrhoea?
Persists >4/52
Ix in diarrhoea?
- 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
Why is faecal elastase tested in diarrheoa Ix?
Marker of pancreatic exocrine sufficiency
What causes osmotic diarrhoea?
Presence of excess unabsorbed substrates in lumen. Common:
-FODMAP malabsorption
Stool volume in osmotic diarrhoea?
Typically
Stool osmotic gap in osmotic diarrhoea?
Increased (>100)
Effect of fasting on osmotic diarrhoea?
Stops with fasting
What causes secretory diarrhoea?
Active anion secretion from enterocytes. Common causes:
- bacterial toxins
- hormone secreting tumours (e.g. carcinoid, gastrinomas)
- laxative abuse
- hyperthyroidism
Stool volume secretory diarrheoa?
> 1L/d; watery.
Stool osmotic gap secretory diarrhoea?
Normal osmolality (osmolar gap
Effect of fasting on secretory diarrhoea?
Diarrhoea persists during fasting.
What causes inflammatory diarrhoea?
Altered membrane permeability (exudation of protein, blood, mucous). Common: -invasive bacteria -CMV colitis -IBD
Stool volume inflammatory diarrhoea?
Generally small.
Stool leukocytes and RBCs?
Increased RBCs and WBCs. May contain frank blood.
Causes of rapid transit diarrhoea?
- IBS
- thyrotoxicosis
- diabetic neuropathy
Mechanisms and causes of slow transit diarrhoea?
Bacterial overgrowth -> bile salt inactivation.
-Intestinal stasis due to anatomical defects (strictures, blind loops, surgical procedures).
