What is the role of a decreased extracellular fluid (ECF) volume in the pathogenesis of diabetes insipidus (DI)?

Updated: Mar 18, 2020
  • Author: Romesh Khardori, MD, PhD, FACP; Chief Editor: George T Griffing, MD  more...
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Answer

Ordinarily, a decrease in the extracellular fluid (ECF) volume elicits the following simultaneous responses:

  • Aldosterone secretion - To preserve sodium retention

  • Thirst - To raise water intake

  • AVP secretion - To increase water retention

Volume depletion activates baroreceptor mechanisms that exert similar effects on aldosterone, thirst, and AVP, whereas osmoreceptor-mediated mechanisms impact thirst and AVP secretion only.

Osmoreceptors for thirst are solute specific, responding preferentially to increased sodium levels in the ECF. Thus, elevated glucose levels in diabetes mellitus do not induce thirst; rather, the increased thirst in uncontrolled diabetes mellitus is secondary to volume depletion from osmotic diuresis.


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