Find information on medical topics, symptoms, drugs, procedures, news and more, written in everyday language.

* This is the Consumer Version. *

Hypernatremia (High Level of Sodium in the Blood)

by James L. Lewis, III, MD

In hypernatremia, the level of sodium in blood is too high.

  • Hypernatremia involves dehydration, which can have many causes, including not drinking enough fluids, diarrhea, kidney dysfunction, and diuretics.

  • Mainly, people are thirsty, and they may become confused or have muscles twitches and seizures.

  • Blood tests are done to measure the sodium level.

  • Usually, fluids are given intravenously to slowly reduce the sodium level in the blood.

In hypernatremia, the body contains too little water for the amount of sodium (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.