Hypernatremia

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Hypernatremia
Other namesHypernatraemia
bleeding in or around the brain[1][2]
TypesLow volume, normal volume, high volume[1]
Diagnostic methodSerum sodium > 145 mmol/L[3]
Differential diagnosisLow blood protein levels[4]
Frequency~0.5% in hospital[2]

Hypernatremia, also spelled hypernatraemia, is a high concentration of

mmol/L (135–145 mEq/L).[5] Hypernatremia is generally defined as a serum sodium level of more than 145 mmol/L.[3] Severe symptoms typically only occur when levels are above 160 mmol/L.[1]

Hypernatremia is typically classified by a person's fluid status into

free water in the body.[6]

If the onset of hypernatremia was over a few hours, then it can be corrected relatively quickly using

babies, those with impaired mental status, and the elderly.[2] Hypernatremia is associated with an increased risk of death but it is unclear if it is the cause.[2]

Signs and symptoms

The major symptom is thirst.[8][9] The most important signs result from brain cell shrinkage and include confusion, muscle twitching or spasms. With severe elevations, seizures and comas may occur.[8]

Severe symptoms are usually due to acute elevation of the plasma sodium concentration to above 157 mmol/L[10] (normal blood levels are generally about 135–145 mmol/L for adults and elderly).[10] Values above 180 mmol/L are associated with a high mortality rate, particularly in adults.[11] However, such high levels of sodium rarely occur without severe coexisting medical conditions.[12] Serum sodium concentrations have ranged from 150 to 228 mmol/L in survivors of acute salt overdosage, while levels of 153–255 mmol/L have been observed in fatalities. Vitreous humor is considered to be a better postmortem specimen than postmortem serum for assessing sodium involvement in a death.[13][14]

Cause

Common causes of hypernatremia include:[8]

Low volume

In those with low volume or hypovolemia:

  • Inadequate intake of free water associated with total body sodium depletion. Typically in elderly or otherwise disabled patients who are unable to take in water as their thirst dictates and also are sodium depleted. This is the most common cause of hypernatremia.
  • Excessive losses of water from the urinary tract – which may be caused by glycosuria, or other osmotic diuretics (e.g., mannitol) – leads to a combination of sodium and free water losses.
  • Water losses associated with extreme sweating.
  • Severe watery diarrhea (
    viral gastroenteritis
    ).

Normal volume

In those with normal volume or euvolemia:

  • Excessive excretion of water from the kidneys caused by
    antidiuretic hormone from the pituitary gland, or impaired responsiveness of the kidneys to it.[15]

High volume

In those with high volume or hypervolemia:

  • Intake of a hypertonic fluid (a fluid with a higher concentration of solutes than the remainder of the body) with restricted free water intake. 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 and free water is not available. There are several recorded cases of forced ingestion of concentrated salt solution in exorcism rituals leading to death.[11]
  • Conn's syndrome
    usually does not lead to hypernatremia unless free water intake is restricted.
  • drinking seawater or soy sauce.[18]

Diagnosis

Hypernatremia is diagnosed when a basic metabolic panel blood test demonstrates a sodium concentration higher than 145 mmol/L.

Treatment

The cornerstone of treatment is administration of free water to correct the relative water deficit. Water can be replaced orally or

congestive heart failure or corticosteroids in nephropathy also can be used.[19]

See also

References

External links