What is "hypernatremia"

n. (context medicine English) An abnormally high concentration of sodium (or salt) in blood plasma.

n. excessive amounts of sodium in the blood; possibly indicating diabetes insipidus [ant: hyponatremia]

Hypernatremia, also spelled hypernatraemia, is a high sodium level in the blood. Early symptoms may include a strong feeling of thirst, weakness, nausea, and loss of appetite. Severe symptoms include confusion, muscle twitching, and bleeding in or around the brain. Normal serum sodium levels are 135 - 145 mEq/liter (135 - 145 mmol/L). Hypernatremia is generally defined as a serum sodium level of more than 145 mEq/L. Severe symptoms typically only occur when levels are above 160 mEq/L.

The cause of hypernatremia is typically classified by a person's fluid status into low volume, normal volume, and high volume. Low volume hypernatremia can occur from sweating, vomiting, diarrhea, diuretic medication, or kidney disease. Normal volume hypernatremia can be due to fever, inappropriately decreased thirst, a prolonged increased breath rate, and diabetes insipidus from lithium among other causes. High volume hypernatremia can be due to hyperaldosteronism, be health care caused such as when too much intravenous 3% normal saline or sodium bicarb is given, or rarely be from eating too much salt. Low blood protein levels can result in a falsely high sodium measurement. The cause can usually be determined by the history of events. Testing the urine can help if the cause is unclear.

If the onset of hypernatremia was over a few hours than it can be corrected relatively quickly using intravenous normal saline and 5% dextrose. 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 which is causing it may need to be stopped. Hypernatremia affects 0.3-1% of people in hospital. It most often occurs in babies, those with impaired mental status, and those who are old. Hypernatremia is associated with an increases the risk of death but it is unclear if it is the cause.