"Severely dehydrated persons, such as people rescued from ocean or desert survival situations, usually have very high blood sodium concentrations. These must be very carefully and slowly returned to normal, since too-rapid correction of hypernatremia may result in brain damage from cellular swelling, as water moves suddenly into cells with high osmolar content."


https://en.wikipedia.org/wiki/Sodium_in_biology


Sadly without a source! If true, it could explain why the Russian dry fasting doctors advise against taking any salt when breaking a dry fast.