A lot depends on how much you are sweating. The more you sweat, the more salt you may need.
As far as “brain swells” and other organs swelling, too little salt can cause that especially if you are drinking a lot of water.
I went into a “salt crisis” once upon some ER-worty crisis event in my diabetes, and for the life of me (heh) can’t remember if it was hypoglycemia or ketoacidosis. And can’t remember the elementary physiology…any help?
I suspect both provoke a sodium imbalance. On either direction of the scale?
More likely it was a derangement in your potassium level, or a thing called the anion gap, which is used as a part of diagnosing metabolic acidosis, especially in diabetics.
Why Everything We Know About Salt May Be Wrong
By GINA KOLATA
NYTimes May 8, 2017
med cites in article