View source for Hypernatremia

{{Infobox comorbidity
| other_names = 
| anesthetic_relevance = Moderate
| anesthetic_management =
If severe, delay elective surgery<br/>
Correct slowly (≤0.5 mEq/hr)
| specialty = Nephrology, neurology
| signs_symptoms =
Depending on severity:
Restlessness<br/>
Irritability<br/>
Ataxia<br/>
Hyperreflexia<br/>
Seizure<br/>
Coma<br/>
Death<br/>
May also have symptoms related to the underlying cause of hypernatremia (e.g. thirst, vomiting, diarrhea, polyuria)
| diagnosis =
Serum sodium
Serum osmolality, urine sodium and osmolality (to determine etiology)
| treatment = Replace free water deficit<br/>
Correct slowly (≤0.5 mEq/hr)
| image = 
| caption = 
}}'''Hypernatremia''' is an abnormally high concentration of sodium in the blood, and can occur on an acute or chronic basis. Hypernatremia leads to a hyperosmolar state, and serum osmolarity often correlates with patient symptoms. Hypernatremia may also be intentionally induced to manage ICP. 

==Anesthetic implications<!-- Briefly summarize the anesthetic implications of this comorbidity. -->==

===Preoperative optimization<!-- Describe how this comorbidity may influence preoperative evaluation and optimization of patients. -->===

*Consider postponing elective cases until treated/stable
*Perform focused neuro exam

===Intraoperative management<!-- Describe how this comorbidity may influence intraoperative management. -->===

* Frequent sodium rechecks to ensure appropriate correction rate

==Related surgical procedures<!-- List and briefly describe any procedures which may be performed specifically to treat this comorbidity or its sequelae. If none, this section may be removed. -->==

* Hypernatremia may be intentionally induced to manage critical ICP before performing a craniotomy

==Pathophysiology<!-- Describe the pathophysiology of this comorbidity. Add subsections as needed. -->==

*Underlying pathophysiology varies depending on etiology (see Diagnosis section), but typically relates to a total body free water deficit
*If severe/acute can lead to
**Brain shrinkage and myelinolysis
**Traction of cerebral vessels, which can cause
***Hemorrhage
***Venous sinus thrombosis
***Infarction

==Signs and symptoms<!-- Describe the signs and symptoms of this comorbidity. -->==
{| class="wikitable"
|+
!Serum osmolality
!Symptoms<ref>{{Cite web|title=Hypernatremia - WikEM|url=https://wikem.org/wiki/Hypernatremia|access-date=2022-03-30|website=wikem.org}}</ref>
|-
|350-375
|Restlessness, irritability
|-
|376-400
|Tremulousness, ataxia
|-
|400-430
|Hyperreflexia, twitching, spasticity
|-
|>430
|Seizure, coma, death
|}

==Diagnosis<!-- Describe how this comorbidity is diagnosed. -->==

*Differential diagnosis guided by comparison of serum and urine osmolality
*If urine osmolality appropriate (700-800 mOsm/kg), differential includes:
**Water loss
***Vomiting
***Diarrhea
***Sweating
**Sodium overload
***Increased sodium intake
***Sodium bicarbonate administration
***Renal sodium retention
**Lack of thirst (rare)
*If urine osmolality low (<300 mOsm/kg), consider diabetes insipidus:
**Central diabetes insipidus (desmopressin challenge/therapy improves urine concentration)
***Head trauma
***CVA
***Tumor
**Nephrogenic diabetes insipidus

==Treatment<!-- Summarize the treatment of this comorbidity. Add subsections as needed. -->==

* If water loss or sodium overload, replace free water deficit
** Typically use 1/2 NS
** Correct slowly (≤0.5 mEq/hr)
** Frequently recheck sodium to ensure correction rate
** If corrected too quickly, risk of cerebral edema
* If central DI, treat with desmopressin

<calculatormodule id="fluidManagement" />
<calculatoroptions patientInputInline="true" />
<calculation id="freeWaterDeficit">Free water deficit</calculation>

==References==

[[Category:Comorbidities]]