In hypernatremia, the level of sodium in blood is too high.
In hypernatremia, the body contains too little water for the amount of sodium (see see Overview of Sodium). The sodium level in the blood becomes abnormally high when water loss exceeds sodium loss, as typically occurs in dehydration.
Usually, hypernatremia results from dehydration (see Dehydration). For example, people may lose body fluids and become dehydrated from drinking too little, vomiting, diarrhea, diuretic use, or excessive sweating. People with diabetes mellitus and high blood sugar levels may urinate excessive amounts, causing dehydration. Diabetes insipidus (which also causes people to urinate excessive amounts although without high blood sugar levels—see Nephrogenic Diabetes Insipidus) and kidney disorders can also cause dehydration. Rarely, adrenal gland disorders can cause mild hypernatremia without dehydration. Excessive administration of salt (usually in hospitalized people) is another rare cause of hypernatremia. Hypernatremia is most common among older people.
Hypernatremia typically causes thirst. The most serious symptoms of hypernatremia result from brain dysfunction. Severe hypernatremia can lead to confusion, muscle twitching, seizures, coma, and death.
Diagnosis and Treatment
The diagnosis is based on blood tests indicating that the sodium level is high.
Hypernatremia is treated by replacing fluids. In all but the mildest cases, dilute fluids (containing water and a small amount of sodium in carefully adjusted concentrations) are given intravenously. The sodium level in blood is reduced very slowly because reducing the level too rapidly can cause permanent brain damage.
Last full review/revision July 2013 by James L. Lewis, III, MD