Ayus JC, Arieff AI
Metabolic consequences of hypernatremia in rats
Am Soc Nephrol
J Am Soc Nephrol (abstract)
(Sep) 7:1347 1996
Hypernatremia is associated with substantial mortality in hospitalized
patients. Mortality exceeds 40 % for all hypernatremic patients, but
approaches 50 % in the elderly. Although the development of
hypernatremia before hospital admission occurs primarily in geriatric
patients, hospital-acquired hypernatremia occurs in an age
distribution similar to that of the general hospitalized population.
Hospital-acquired hypernatremia is primarily iatrogenic, resulting
from inadequate and inappropriate prescription of fluids to patients
with increased water losses and impaired thirst or restricted free
water intake.
These investigators studied the relationship between hypernatremia and
hyperglycemia in rats made hypernatremic with intraperitoneal
hypertonic saline and water deprivation. Severe hypernatremia tripled
the glucose concentration. Rats rehydrated with oral water survived.
Mortality was 25% in rats rehydrated with 280 mM glucose solution and
80 % with 560 mM glucose. They observed substantial weight loss in
hypernatremic rats from decreased food intake. They measured an
increase in insulin and C-peptide concentration in hyperglycemic rats.
The authors conclude that rehydration with water is superior to
glucose containing solutions. Although they conclude that cachexia is
related to the hypernatremia, this observation may be the result of
the effects of hypertonic peritoneal solution and the non-specific
effects of the induced severe metabolic derangements. Further, the
increased insulin and C-peptide levels are likely an appropriate
physiological response to hyperglycemia rather than postulated insulin
resistance.
Comment: Treatment of hypernatremia is often
inadequate or delayed. This work emphasizes the need to better manage
hypernatremia and provides insights into the pathophysiology of the
disorder. (George R. Aronoff, M.D., University of Louisville,
Kentucky)
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Am Soc Nephrol
Sodium/water transport :
Hypernatremia