[1] Low volume hypernatremia can occur from sweating, vomiting, diarrhea, diuretic medication, or kidney disease.

[1] Normal volume hypernatremia can be due to fever, extreme thirst, prolonged increased breath rate, diabetes insipidus, and from lithium among other causes.

[1] High volume hypernatremia can be due to hyperaldosteronism, excessive administration of intravenous normal saline or sodium bicarbonate, or rarely from eating too much salt.

[6] 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.

[8][9] The most important signs result from brain cell shrinkage and include confusion, muscle twitching or spasms.

[8] Severe symptoms are usually due to acute elevation of the plasma sodium concentration to above 157 mmol/L[10] (normal blood levels are generally about 135–145 mmol/L for adults and elderly).

[12] 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.

Therefore, significant hypernatremia should be treated carefully by a physician or other medical professional with experience in treatment of electrolyte imbalance.