Hypernatremia causes

; Associate Editor-In-Chief: ; Assistant Editor(s)-In-Chief: Jack Khouri

Overview
Hypernatremia can be cause by many disease processes and drugs. Water loss, whatever the cause is (see below),is the most important mechanism leading to sodium excess. Diarrhea, diabetes insipidus, diuretics, osmotic agents, insensible losses or impaired thirst response due to any disease process affecting the hypothalamus. Primary sodium excess is a rare cause of hypernatremia and ca be due to sodium salt ingestion or minaralocorticoid excess.

Causes
Hypernatremia can result from water loss (most common) or sodium retention (rare).

Causes of water loss

 * Inadequate intake of water: typically in elderly or otherwise disabled patients who are unable to take in water as their thirst dictates. This is the most common cause of hypernatremia. Hypothalamic disorders can lead to impairement of the thirst mechanism (primary hypodipsia, essential hypernatremia caused by the loss of the hypothalamic osmoreceptor function (the plasma osmolarity sensor that stimulates thirst once the plasma is hyperosmolar))
 * Renal loss: Inappropriate excretion of water, often in the urine, which can be due to medications like diuretics or lithium or can be due to a medical condition called diabetes insipidus. Osmotic diuresis can occur when osmotically active substances are present in large amounts in the plasma (glucose, [[urea, mannitol, etc)
 * GI loss: osmotic diarrhea (infectious, malabsorptive, lactulose intake)
 * Insensible losses: excessive sweating in the context of exercise or warm climate
 * Water loss into cells: seizure, severe exercise, rhabdomyolysis

Causes of increased sodium retention

 * Intake of a hypertonic fluid (a fluid with a higher concentration of solutes than the remainder of the body). This is relatively uncommon, though it can occur after a vigorous resuscitation where a patient receives a large volume of a concentrated sodium bicarbonate solution. Ingesting seawater also causes hypernatremia because seawater is hypertonic.
 * Mineralcorticoid excess due to a disease state such as Conn's syndrome or Cushing's Syndrome.