text: If the onset of hypernatremia was over a few hours, then it can be corrected relatively quickly using intravenous normal saline and 5% dextrose in water. Otherwise, correction should occur slowly with, for those unable to drink water, half-normal saline. Hypernatremia due to diabetes insipidus as a result of a brain disorder, may be treated with the medication desmopressin. If the diabetes insipidus is due to kidney problems the medication causing the problem may need to be stopped or the underlying electrolyte disturbance corrected. Hypernatremia affects 0.3–1% of people in hospital. It most often occurs in babies, those with impaired mental status, and the elderly. Hypernatremia is associated with an increased risk of death, but it is unclear if it is the cause.
  Signs and symptoms
  The major symptom is thirst.  The most important signs result from brain cell shrinkage and include confusion, muscle twitching or spasms. With severe elevations, seizures and comas may occur.
  Severe symptoms are usually due to acute elevation of the plasma sodium concentration to above 157 mmol/L  (normal blood levels are generally about 135–145 mmol/L for adults and elderly). Values above 180 mmol/L are associated with a high mortality rate, particularly in adults. However, such high levels of sodium rarely occur without severe coexisting medical conditions. Serum sodium concentrations have ranged from 150 to 228 mmol/L in survivors of acute salt overdosage, while levels of 153–255 mmol/L have been observed in fatalities. Vitreous humor is considered to be a better postmortem specimen than postmortem serum for assessing sodium involvement in a death.
  Cause
  Common causes of hypernatremia include:
  Low volume
  In those with low volume or hypovolemia:
  Inadequate intake of free water associated with total body sodium depletion. Typically in elderly or otherwise disabled patients who are unable to take in water as their thirst dictates and also are sodium depleted. This is the most common cause of hypernatremia.