Hypernatremia

Template:Short description Template:Infobox medical condition (new) Hypernatremia, also spelled hypernatraemia, is a high concentration of sodium in the blood.<ref name=Muh2016>Template:Cite journal</ref> Early symptoms may include a strong feeling of thirst, weakness, nausea, and loss of appetite.<ref name=BMJ2006/> Severe symptoms include confusion, muscle twitching, and bleeding in or around the brain.<ref name=BMJ2006/><ref name=Lin2005/> Normal serum sodium levels are 135–145 mmol/L (135–145 mEq/L).<ref>Template:Cite book Template:Dead link</ref> Hypernatremia is generally defined as a serum sodium level of more than 145 mmol/L.<ref name=Muh2016/> Severe symptoms typically only occur when levels are above 160 mmol/L.<ref name=BMJ2006/>

Hypernatremia is typically classified by a person's fluid status into low volume, normal volume, and high volume.<ref name=BMJ2006/> Low volume hypernatremia can occur from sweating, vomiting, diarrhea, diuretic medication, or kidney disease.<ref name=BMJ2006/> Normal volume hypernatremia can be due to fever, extreme thirst, prolonged increased breath rate, diabetes insipidus, and from lithium among other causes.<ref name=BMJ2006 /> High volume hypernatremia can be due to hyperaldosteronism, excessive administration of intravenous normal saline or sodium bicarbonate, or rarely from eating too much salt.<ref name=BMJ2006/><ref name=Lin2005/> Low blood protein levels can result in a falsely high sodium measurement.<ref name=Kli2015>Template:Cite book</ref> The cause can usually be determined by the history of events.<ref name=BMJ2006/> Testing the urine can help if the cause is unclear.<ref name=BMJ2006>Template:Cite journal</ref> The underlying mechanism typically involves too little free water in the body.<ref>Template:Cite book</ref>

If the onset of hypernatremia was over a few hours, then it can be corrected relatively quickly using intravenous normal saline and 5% dextrose in water.<ref name=BMJ2006/> Otherwise, correction should occur slowly with, for those unable to drink water, half-normal saline.<ref name=BMJ2006/> Hypernatremia due to diabetes insipidus as a result of a brain disorder, may be treated with the medication desmopressin.<ref name=BMJ2006/> If the diabetes insipidus is due to kidney problems the medication causing the problem may need to be stopped or the underlying electrolyte disturbance corrected.<ref name=BMJ2006/><ref name="Khanna2006">Template:Cite journal</ref> Hypernatremia affects 0.3–1% of people in hospital.<ref name=Lin2005/> It most often occurs in babies, those with impaired mental status, and the elderly.<ref name=Lin2005/> Hypernatremia is associated with an increased risk of death, but it is unclear if it is the cause.<ref name=Lin2005>Template:Cite journal</ref>

Signs and symptomsEdit

The major symptom is thirst.<ref name=MerckManual/><ref name=oz>Department of Health & Human Services, State Government of Victoria, Australia Better Health Channel: Salt Template:Webarchive Last updated: May 2014</ref> The most important signs result from brain cell shrinkage and include confusion, muscle twitching or spasms. With severe elevations, seizures and comas may occur.<ref name=MerckManual>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Severe symptoms are usually due to acute elevation of the plasma sodium concentration to above 157 mmol/L<ref name="Reynolds 702–705">Template:Cite journal</ref> (normal blood levels are generally about 135–145 mmol/L for adults and elderly).<ref name="Reynolds 702–705" /> Values above 180 mmol/L are associated with a high mortality rate, particularly in adults.<ref name="Ofran_et_al_2004"/> However, such high levels of sodium rarely occur without severe coexisting medical conditions.<ref>Template:Cite book</ref> 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.<ref>Template:Cite journal</ref><ref>Template:Cite book</ref>

CauseEdit

Common causes of hypernatremia include:<ref name=MerckManual/>

Low volumeEdit

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.Template:Cn
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.Template:Cn
Water losses associated with extreme sweating.Template:Cn
Severe watery diarrhea (osmotic diarrhea results in hypotonic (dilute) watery diarrhea resulting in significant loss of free water and a higher concentration of sodium in the blood; this type of water loss can also be seen with viral gastroenteritis).Template:Cn

Normal volumeEdit

In those with normal volume or euvolemia:

Excessive excretion of water from the kidneys caused by diabetes insipidus, which involves either inadequate release of antidiuretic hormone from the pituitary gland, or impaired responsiveness of the kidneys to it.<ref name="pmid24286605">Template:Cite journal</ref>

High volumeEdit

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.<ref name="Ofran_et_al_2004" />
Mineralcorticoid excess due to a disease state such as Conn's syndrome usually does not lead to hypernatremia unless free water intake is restricted.
Salt poisoning is the most common cause in children.<ref name="pmid1249688">Template:Cite journal</ref><ref name="pmid10189662">Template:Cite journal</ref> It has also been seen in a number of adults with mental health problems.<ref name="Ofran_et_al_2004">Template:Cite journal</ref> Too much salt can also occur from drinking seawater or soy sauce.<ref>Template:Cite journal</ref>

DiagnosisEdit

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

TreatmentEdit

The cornerstone of treatment is administration of free water to correct the relative water deficit. Water can be replaced orally or intravenously. Water alone cannot be administered intravenously (because of osmolarity issues leading to rupturing of red blood cells in the bloodstream), but rather can be given intravenously in solution with dextrose (sugar) or saline (salt). However, overly rapid correction of hypernatremia is potentially very dangerous. The body (in particular the brain) adapts to the higher sodium concentration. Rapidly lowering the sodium concentration with free water, once this adaptation has occurred, causes water to flow into brain cells and causes them to swell. This can lead to cerebral edema, potentially resulting in seizures, permanent brain damage, or death. Therefore, significant hypernatremia should be treated carefully by a physician or other medical professional with experience in treatment of electrolyte imbalance. Specific treatments such as thiazide diuretics (e.g., chlorthalidone) in congestive heart failure or corticosteroids in nephropathy also can be used.<ref>Template:Cite journal</ref>