Complications

Complication
Timeframe
Likelihood
short term
medium

A potential major consequence of hyponatremia.

Rapid changes in serum sodium concentration can cause severe, permanent, and sometimes lethal brain injury.[49]

If hyponatremia develops acutely (i.e., in <48 hours), the brain does not have time to adapt and cerebral edema occurs, leading to symptoms of nausea, vomiting, altered mental status, and eventually seizures and/or brain herniation and death.[2]

This is a medical emergency requiring prompt infusion of hypertonic 3% saline.[5]

short term
medium

Osmotic demyelination syndrome can lead to permanent neurological dysfunction.[3]​ 

Characterized by altered mental status and/or reduced motor functioning and abnormalities of balance.

Diagnosis is confirmed on brain magnetic resonance imaging, which shows typical lesions in the pons, thalamus, or other areas of white matter.[Figure caption and citation for the preceding image starts]: Brain magnetic resonance imaging of a patient with central pontine myelinolysis showing: (a) trident-shaped hyperintensity within the pons; (b) hypointensity within the basis pontis; and (c) hyperintense focus in the central ponsBMJ Case Reports 2013; doi:10.1136/bcr-2013-009970 [Citation ends].com.bmj.content.model.Caption@61e6efd0

Can be prevented by using a slow rate of serum sodium correction (i.e., <8 mEq/L/day).[24]

If overcorrection occurs, administering free water to reduce sodium back to the desired level has been shown to reduce the risk of osmotic demyelination in animal studies.[2]​​

long term
low

Has been reported with long-term, chronic hyponatremia.[3][35]​ Chronic hyponatremia might act additively or synergistically with other causes of bone loss that occur commonly with aging, thereby contributing to morbidity and mortality.[61]

Osteoporosis

variable
medium

Compared with normal serum sodium levels, mild chronic hyponatremia (among patients admitted to the medical emergency department) is associated with a substantially increased risk of falls.[3][23][36]​​[60] An increased risk of falls in the elderly is a risk factor for fractures.[23][36]

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