It is one of three forms ofdehydration.
Typically, it is treated by rehydrating the body with water or treating the underlying cause.
Other times this may happen is with excessive sweating or not drinking enough water.

Photo composite by Mira Norian for Verywell Health; Getty Images
Salt vs. Having both in high amounts can lead to dehydration, as well as other health conditions.
They may also ask questions about lifestyle, including your diet and how much water you drink.
The most notable and detrimental is death, but that only occurs in rare and significantly severe cases.

It is considered a medical emergency and can lead to failure of multiple organs if left untreated.
Doing so can lead to an excess amount of water in brain cells, known ascerebral edema.
Osmosis from Elsevier.Hypertonic dehydration.
Centers for Disease Control and Prevention.Effects of sodium and potassium.
Chan School of Public Health.Salt and sodium.
doi: 10.1093/ageing/afad193
Medline Plus.Dehydration.