Wednesday, November 2, 2005

Nephrology Cases #7: Severe Asymptomatic Hypernatremia

Interesting, if you like this sort of thing.

Reprinted from the NEPHROL mailing list:
I recently saw a patient with adipsic (or "essential") hypernatremia (see Brenner and Rector, 3rd edition, page 408) following resection of a cerebral aneurysm earlier this year (done elsewhere, no details known). He presented with a sodium level of 178, completely asymptomatic, and completely devoid of thirst, even resisting water intake. His urine osmolarity, without exogenous vasopressin, was over 900. He was treated with intravenous water, and when his sodium got into the high 150s, his urine osmolarity decreased under 200. After about a two week hospitalization (where he often pulled his IVs out, and mostly refused to drink), he never got his sodium under around 154. He was discharged on oral vasopressin replacement, and advice to have scheduled water intake even without thirst.

Unfortunately, his mental status is not normal, and he seems unable to follow the advised water intake. He was readmitted with a sodium of 168, again completely asymptomatic, and again without any thirst. We started up again, quite reflexively, with the IV water replacement.

I'm wondering if any of this is necessary, and if I can drum up the chutzpah, cojones, courage, and/or trust in myself to tell his internist not to worry, and not to hospitalize him-- that his hypernatremia is always going to be chronic and asymptomatic, it will range between maybe 155 and 178, depending on how much he drinks, and that there is no morbidity or mortality associated with chronic hypernatremia per se, even of this magnitude. Of course, these are scary numbers, and I'm naturally reluctant to make such a recommendation without some support in the literature- which I am unable to find. Chronic hypernatremia of this magnitude doesn't seem to exist: you might need to have the "perfect storm" confluence of a rare disease (adipsic hypernatremia) in a mentally challenged patient...

Sheldon Hirsch, MD
Chicago, IL
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1 comment:

Anonymous said...

I had the pleasure of taking care of a similar individual. He had a stroke that took out the hypothalamus and hippocampus in such a way that he had hypernatremia and no shortterm memory.

His devoted wife took excellent care of him.

He was a bit off his game and on the hypernatremic side so his PCP admitted him for IV rehydration.

There was a component of "social admission" because the PCP wanted to give the wife a rest as a patient like this can be somewhat high maintainance. That being said, it was still a very interesting learning experience.