Hypernatremia is defined as a plasma sodium concentration of >145 mEq/L.
Hypernatremia is a state of hyperosmolality, and is primarily a result of water deficit or, rarely, sodium gain. Due to the maintenance of osmotic equilibrium, intracellular fluid (ICF) becomes volume contracted. The appropriate responses are increased water intake stimulated by thirst, and the excretion of the minimal amount of maximally concentrated urine.
Infants, and adults with cognitive impairment, are most commonly affected because of their inability to express thirst and limited access to water.
Hypernatremia is often the result of several disease processes, and the underlying cause needs to be elicited to correct the sodium balance. The physical consequences of hypernatremia can be severe, and overlap with many of the precipitating causes.
Hypernatremia generally occurs in patients at extremes of age, or in those who are physically or cognitively debilitated.
An incidence of 1% and a prevalence of 2.5% have been reported for patients admitted to the hospital.
Mortality rates range between 45% and 60% for all patients, but may be as high as 80% for older patients.
One study investigating the epidemiology of sodium disturbances in the ICU setting found that both hypernatremia and hyponatremia are common in ICU patients, and that they are associated with adverse patient outcomes.
Hypernatremia is diagnosed in males and females in equal numbers.
- Central diabetes insipidus
- Hyperosmolar hyperglycemic state (HHS)
- Nephrogenic diabetes insipidus
- Severe diarrhea
- Limited access to water
- Primary hypodipsia
- Cushing syndrome
- Primary aldosteronism
- Postobstructive diuresis
- Laxative and bowel cleansing agent use
- Enteric fistulae
- Heat exposure
- Severe burns
- Inadequate breast-feeding of infants
- Salt ingestion
- High-protein diet
- Use of intravenous sodium chloride
- Use of intravenous sodium bicarbonate
- Enteral feeding
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