Aetiology

Aetiology varies with the region and socio-economic status.

• in developed countries - irritable bowel syndrome, inflammatory bowel disease, malabsorption syndrome, and chronic infections predominate
• in developing countries - chronic bacterial, mycobacterial, and parasitic infections are the most common causes

The causes of chronic diarrhoea can be divided into: (1, 2)

• colonic pathology such as
  • inflammatory bowel disease
  • diverticular disease of the colon
  • carcinoma of the colon
• small bowel pathology
  • coeliac disease
  • Crohn's disease
  • other small bowel enteropathies (e.g. Whipple's disease, tropical sprue, amyloid, intestinal lymphangiectasia)
  • small bowel bacterial overgrowth
  • mesenteric Ischaemia
  • giardiasis and other chronic infection
• pancreatic disease including
  • chronic pancreatitis
  • carcinoma of the pancreas
• systemic disease, including
  • thyrotoxicosis
  • uraemia
  • carcinoid syndrome
  • Whipple's disease
• other
  • drug reactions including
  • antibiotics
  • purgatives
  • magnesium-containing indigestion medication
  • digoxin
  • surgery - post-gastrectomy
  • factitious diarrhoea
  • anxiety
  • laxatives

References:

1. Guandalini S, Vaziri H 2011. Diarrhea. Diagnostic and therapeutic advantages. 1st edition
2. Gupta S et al. Chronic diarrhoea--all in the bowel? J R Soc Med. 2007;100(8):379-81.