Management of Hyponatremia

Introduction to Hyponatremia

• Hyponatremia is a condition where serum sodium levels are lower than normal, categorized as mild (126-135 mEq/L), moderate (120-125 mEq/L), or severe (<120 mEq/L) 1, 2
• Volume status should be assessed to classify the type of hyponatremia as hypovolemic, euvolemic, or hypervolemic 2

Treatment Approach

• The European Clinical Practice Guidelines recommend gradual tapering of urea tablets over 2-4 weeks while monitoring serum sodium levels, with a goal to discontinue high sodium diet once serum sodium remains stable above 135 mEq/L for at least one week 3
• The management of chronic hyponatremia should focus on gradual correction of sodium levels with a goal rate of 4-6 mEq/L per 24 hours, not exceeding 8 mEq/L per 24-hour period to prevent osmotic demyelination syndrome, especially in patients with a history of stroke 1
• Asymptomatic patients may not require specific management apart from monitoring 1

Medication Considerations

• Thiazide diuretics like indapamide are a common cause of hyponatremia and should be avoided in patients with a history of severe hyponatremia, as recommended by the Korean Association for the Study of the Liver guidelines 4
• Medications that may worsen hyponatremia, such as thiazide diuretics and SSRIs, should be ceased 1
• The following table summarizes key considerations for managing hyponatremia:

Correction of Hyponatremia

• Severe hyponatremia may require more aggressive fluid restriction, albumin infusion, or hypertonic (3%) saline, aiming for an initial correction of 5 mEq/L in the first hour, with subsequent correction not exceeding 8 mEq/L per 24-hour period 1, 2
• Patients with severe hyponatremia and neurological symptoms may require hospital admission for monitored correction, limiting the correction rate to <12 mEq/L in 24 hours to prevent osmotic demyelination syndrome 5, 6
• Rapid correction exceeding 8 mEq/L per 24 hours increases the risk of osmotic demyelination syndrome, especially in elderly patients with a history of stroke 1, 2

Special Considerations

• Patients with a history of stroke are at increased risk for osmotic demyelination syndrome with rapid correction of hyponatremia, and a more conservative correction rate of 4-6 mEq/L per day should be used 1
• Age, medication combinations, and duration of schizophrenia are risk factors to consider when managing hyponatremia in schizophrenia patients, and treatment-resistant schizophrenia may require more intensive monitoring of sodium levels, as recommended by the American Psychiatric Association 6
• The American Psychiatric Association recommends reviewing current antipsychotic regimens and considering switching from high-risk antipsychotics to lower-risk alternatives for managing hyponatremia in schizophrenia patients, while maintaining effective schizophrenia treatment 5, 6

Pharmacological Interventions

• Vasopressin Receptor Antagonists (Vaptans), such as tolvaptan, may be considered for short-term use (≤30 days) in persistent hyponatremia, with a starting dose and titration based on response, as recommended by the American College of Cardiology 7, 5, 8
• Tolvaptan therapy should be limited to minimize the risk of liver injury, and correction of serum sodium should not exceed 12 mEq/L in 24 hours to prevent osmotic demyelination 7, 8
• Urea is considered an alternative second-line therapy if tolvaptan is contraindicated, and is effective and safe for chronic management 7
• Tolvaptan should be avoided in patients who cannot sense or respond to thirst, and in patients with liver disease, due to the risk of drug interactions with CYP3A inhibitors, as recommended by the Journal of Hepatology 9