How to manage symptomatic hyponatremia (low sodium levels) secondary to hyperglycemia (high blood sugar)?

Management of Symptomatic Hyponatremia Secondary to Hyperglycemia

Immediate Correction of Measured Sodium

The first critical step is to calculate the corrected sodium level, as hyperglycemia causes pseudohyponatremia—add 1.6 mEq/L to the measured sodium for every 100 mg/dL of glucose above 100 mg/dL. 1 This correction is essential because the measured sodium underestimates the true sodium concentration in hyperglycemic states.

Treatment Algorithm Based on Corrected Sodium and Symptoms

If Corrected Sodium is Normal or High (≥135 mEq/L)

• The hyponatremia is pseudohyponatremia—treat the hyperglycemia, not the sodium. 1
• Start continuous IV insulin infusion at 0.1 units/kg/hour (5-7 units/hour in adults) after excluding hypokalemia (K+ >3.3 mEq/L). 1
• Use 0.45% NaCl at 4-14 mL/kg/hour if corrected sodium is normal or elevated. 1
• Once glucose reaches 250 mg/dL, switch to 5% dextrose with 0.45-0.75% NaCl. 1
• The induced change in serum osmolality should not exceed 3 mOsm/kg/H2O per hour. 1

If Corrected Sodium is Low (<135 mEq/L) with Severe Symptoms

This represents true hyponatremia requiring urgent treatment with 3% hypertonic saline, targeting correction of 6 mEq/L over 6 hours or until severe symptoms resolve. 2, 3, 4

• Severe symptoms include seizures, coma, altered mental status, or cardiorespiratory distress. 2, 3
• Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, repeatable up to three times. 2
• Maximum correction must not exceed 8 mEq/L in 24 hours to prevent osmotic demyelination syndrome. 1, 2, 3
• Monitor serum sodium every 2 hours during initial correction. 2
• Simultaneously treat hyperglycemia with insulin as above, but prioritize correcting the true hyponatremia first. 1

If Corrected Sodium is Low with Mild/No Symptoms

• Use 0.9% NaCl at 4-14 mL/kg/hour for volume repletion if corrected sodium is low. 1
• Add potassium 20-30 mEq/L (2/3 KCl and 1/3 KPO4) once renal function is assured. 1
• Treat hyperglycemia with insulin infusion as described above. 1
• Correct estimated fluid deficits within 24 hours. 1

Critical Monitoring Parameters

• Check serum sodium, glucose, and potassium every 2-4 hours initially. 1, 2
• Calculate corrected sodium with each glucose measurement. 1
• Monitor for signs of cerebral edema, particularly in pediatric patients (<20 years). 1
• Assess hemodynamic status, fluid input/output, and mental status continuously. 1

Common Pitfalls to Avoid

• Never treat measured sodium without correcting for hyperglycemia—this leads to inappropriate fluid selection. 1
• Never exceed 8 mEq/L sodium correction in 24 hours, as this risks osmotic demyelination syndrome. 2, 3, 4
• Avoid fluid overload, which can cause symptomatic cerebral edema, especially in children. 1
• Do not use hypotonic fluids initially if corrected sodium is low—use 0.9% NaCl for volume repletion. 1
• Never correct hyperglycemia too rapidly (aim for 50-75 mg/dL/hour decrease). 1

Special Considerations for High-Risk Patients

• Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require even more cautious sodium correction at 4-6 mEq/L per day. 2, 3
• In pediatric patients, initial fluid therapy should not exceed 50 mL/kg over the first 4 hours. 1
• If overcorrection occurs, immediately switch to D5W and consider desmopressin to relower sodium. 2