Hyponatremia, characterized by low plasma sodium concentration (pNa), is the most prevalent electrolyte disorder in hospitalized patients, affecting about 15%. While the majority of cases are mild, with pNa levels at or above 130 mmol/L, about 4% of patients experience severe hyponatremia with pNa dropping below 130 mmol/L. The leading cause of this significant drop in pNa is the Syndrome of Inappropriate Antidiuresis (SIAD), which occurs due to an excessive release of arginine vasopressin (AVP) despite low serum tonicity. In cases of severe symptomatic hyponatremia, which may present with symptoms like vomiting, seizures, and a reduced conscious state, it is considered a medical emergency. Immediate treatment with a bolus of hypertonic saline, specifically 100 mL of 3% NaCl for up to three doses, is recommended to increase pNa by 4 to 6 mmol/L, aiming to reduce intracranial pressure (ICP).
For chronic or uncertain-duration hyponatremia, to prevent osmotic demyelination syndrome (ODS),…