Colon Diarrhoea

Diarrhoea is the passage of three or more loose or liquid stools per day, or more frequent looser stools than is typical for an individual. People may also experience steatorrhoea, which is the passage of pale, smelly, explosive stools that are difficult to flush.


What are the causes of diarrhoea?

Diarrhoea has many causes. Most commonly short-lived or ‘acute’ diarrhoea is due to infection, and often requires no specific treatment.

Longer-standing or ‘chronic’ symptoms can be due to:

  • Irritable bowel syndrome (IBS)
  • Coeliac disease
  • Inflammatory conditions
    • Crohn’s disease
    • Ulcerative colitis
    • Microscopic colitis
  • Colon cancer
  • Bile acid malabsorption
  • Endocrine causes
    • Thyroid disease

What are the causes of steatorrhoea?

Steatorrhoea (pale, fatty, difficult to flush stool) is indicative of malabsorption. Whilst there are many causes, those seen commonly include:

  • Coeliac disease
  • Abnormal growth of bacteria in the small bowel (Small bowel bacterial overgrowth)
  • Loss of pancreas digestive enzymes

How is diarrhoea investigated?

There are a number of investigations that may be employed to determine the cause of diarrhoea. The order in which you are offered these investigations will depend in part on the most likely cause(s) as determined by your medical history.

  • Blood tests including: full blood count, kidney and liver function tests, inflammatory markers, coeliac antibody, thyroid function
  • Stool tests:
    • Tests for infectious causes of diarrhoea
    • Test for inflammation: Faecal calprotectin
    • Test for blood: Faecal Immunochemical Testing (FIT)
    • Test for pancreas function: Faecal elastase
  • Endoscopic tests:
    • Colonoscopy (or sometimes flexible sigmoidoscopy)
    • Upper GI endoscopy / OGD
  • Cross-sectional imaging
    • CT colonography
    • Small bowel MRI scan
  • Other imaging
    • SeHCAT scan

How is diarrhoea treated?

The treatment of diarrhoea depends on defining the cause.