Pathophysiology of Diarrhea and Its Clinical Implications

Irshad A. Sheikh, Rana Ammoury, Fayez K Ghishan

Research output: Chapter in Book/Report/Conference proceedingChapter

3 Scopus citations


In the gastrointestinal tract, ionic balance, fluid absorption, and secretion are vital to maintain homeostasis allowing for the maintenance of a membrane potential, adequate nutrient intake, normal gut motility, protection against microbes, and epithelial cell viability. This homeostatic state relies on the normal physiological function of the small and large intestinal cells and a complex array of hormonal mechanisms that control gut motility as well as entry and exit of fluid into the gastrointestinal lumen. Approximately, 8-10L of fluid pass through the small intestinal lumen daily. It is remarkable that in health, the small intestine absorbs all but 1.5L and the colon absorbs the rest leaving approximately 100mL of fluid to be lost in stool. Intestinal ion transport mechanisms play a significant role in determining overall fluid balance in the gut, namely chloride secretion, electroneutral sodium chloride absorption and electrogenic sodium absorption. Moreover, a variety of hormones and neurotransmitters are synthesized locally in the intestinal mucosa and modify intestinal ion transport either directly by binding to receptors on the basolateral membrane of enterocytes or indirectly via the release of other effectors. In certain pathophysiologic states, the finely tuned ionic-fluid exchange becomes dysfunctional as a result of the failure of compensatory pro-absorptive/antisecretory mechanisms. Different pathophysiological mechanisms causing diarrhea, mainly secretory, osmotic, inflammatory, altered intestinal transit and loss of functional absorptive area, have been elucidated.

Original languageEnglish (US)
Title of host publicationPhysiology of the Gastrointestinal Tract, Sixth Edition
Number of pages19
ISBN (Electronic)9780128099544
ISBN (Print)9780128124260
StatePublished - Jan 1 2018


  • Diarrhea
  • Intestinal absorption
  • Intestinal ion transport
  • Intestinal secretion

ASJC Scopus subject areas

  • General Medicine


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