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Hyponatremia
Background
Overview
Definition
Hyponatremia an electrolyte disorder characterized by low serum sodium concentration, and is typically defined as a serum sodium of < 135 mEq/L.
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Pathophysiology
Causes of hyponatremia include increased water intake (psychogenic polydipsia), low dietary solute intake (tea and toast diet), decreased water excretion secondary to elevated plasma ADH levels (volume depletion, SIADH, severe hypothyroidism, adrenal insufficiency), and expansion of plasma volume in the context of edematous states.
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Epidemiology
The prevalence of hyponatremia in the general population of the US is 1.72%.
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Disease course
Treatment of hyponatremia requires careful attention to avoid overly rapid correction of serum sodium, which can lead to osmotic demyelination syndrome, permanent neurological impairment, and death.
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Prognosis and risk of recurrence
Approximately 40% of patients with osmotic demyelination syndrome recover fully, whereas 25% have persistent neurological deficits. Mortality associated with osmotic demyelination syndrome is approximately 6%.
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Guidelines
Key sources
The following summarized guidelines for the evaluation and management of hyponatremia are prepared by our editorial team based on guidelines from the American Academy of Family Physicians (AAFP 2023), the American Heart Association (AHA/ASA 2023), the Korean Society of Nephrology (KSN/KSEBPR 2022), the American Association for the Study of Liver Diseases (AASLD 2021), the Wilderness Medical Society (WMS 2020), the ...
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