How does declining renal function affect hyponatremia?

Updated: Aug 16, 2019
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

With declining renal function, the ability to excrete free water decreases, and the more advanced the reduction in glomerular filtration rate (GFR), the easier it is for patients to become hyponatremic with unrestricted fluid intake. In patients on long-term dialysis with no urine output, fluid intake no greater than insensible losses leads to a predictable fall in serum Na, which, however, is not sustained because of regular maintenance dialysis.

Reset osmostat

Persons with this entity have a normal response to changes in osmolality, but their threshold for ADH release is reduced. Therefore, they have a lower, but stable, plasma Na+ concentration. Some individuals probably carry a nonsynonymous polymorphism (P19S) in the transient receptor potential vanilloid 4 (TRPV4) channel, part of the osmoreceptor system, since this mutation has been shown to be associated with hyponatremia. [25]


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