01/06/2026
π Yasir Alam's PACES HACKS #7
Decoding Diarrhoea: Let the Stool Tell the Story
When assessing a patient with diarrhoea, the pattern of stool often points directly toward the diagnosis.
1. Large-Volume Watery Diarrhoea β Secretory
Clue: Continues despite fasting.
Think: The gut is actively secreting fluid.
Causes:
Cholera
Enterotoxigenic E. coli
VIPoma
Carcinoid syndrome
Memory Tip: "Still flowing even when not feeding."
2. Moderate-Volume Loose Stool β Osmotic
Clue: Improves or stops with fasting.
Think: Something in the bowel is drawing water in.
Causes :
Lactose intolerance
Magnesium-containing laxatives
Sorbitol ingestion
Memory Tip: "No food = no osmotic load = no diarrhoea."
3. Bloody Diarrhoea + Abdominal Pain β Inflammatory
Clue: Blood, mucus, pain, and urgency.
Think: Inflammation or ulceration of the bowel.
Causes:
Inflammatory bowel disease (IBD)
Infective colitis
Ischaemic colitis
Red Flag: Blood in stool is never normal.
4. Pale, Bulky, Greasy Stool β Steatorrhoea
Clue: Difficult to flush, foul-smelling, oily appearance.
Think: Fat malabsorption.
Causes:
Coeliac disease
Chronic pancreatitis
Pancreatic insufficiency
Memory Tip: "Fat in the stool = failure to absorb fat."
5. Urgency β Think Proctitis
Clue: Sudden, compelling need to open bowels.
Think: Re**al inflammation.
Causes:
Ulcerative colitis
Infectious proctitis
Radiation proctitis
Exam Pearl: Urgency often localizes pathology to the re**um.
6. Nocturnal Diarrhoea β Organic Disease
Clue: Wakes the patient from sleep.
Think: Genuine pathology rather than a functional disorder.
Causes:
Inflammatory bowel disease (IBD)
Diabetic autonomic neuropathy
Microscopic colitis
Exam Pearl: IBS rarely causes nocturnal symptoms.
