Maximum Sodium Correction in 24 Hours
The maximum recommended sodium correction in 24 hours is 8 mmol/L for most patients with chronic hyponatremia, with even more conservative limits of 4-6 mmol/L per day for high-risk populations. 1, 2
Standard Correction Limits
For average-risk patients, the maximum correction should not exceed 8 mmol/L in any 24-hour period. 1, 2 Some guidelines allow up to 10-12 mmol/L in 24 hours for standard-risk patients, but this higher limit carries increased risk of osmotic demyelination syndrome. 2, 3
For high-risk patients—including those with advanced liver disease, alcoholism, malnutrition, severe hyponatremia (<115 mEq/L), hypophosphatemia, hypokalemia, or prior encephalopathy—the maximum correction must be limited to 4-6 mmol/L per day, not exceeding 8 mmol/L in 24 hours. 1, 2, 3
Critical Safety Considerations
The 8 mmol/L limit exists to prevent osmotic demyelination syndrome, a devastating neurological complication that can cause dysarthria, dysphagia, quadriparesis, locked-in syndrome, or death. 1, 4, 5 This complication typically occurs 2-7 days after overly rapid correction. 1
Recent evidence suggests that osmotic demyelination syndrome can occur even with correction rates ≤10 mEq/L per 24 hours in patients with severe hyponatremia (<115 mEq/L) and multiple risk factors. 3 In these highest-risk patients, limiting correction to <8 mEq/L per 24 hours is essential. 3
Exception: Severe Symptomatic Hyponatremia
For patients with severe symptoms (seizures, coma, altered mental status), initial rapid correction of 6 mmol/L over the first 6 hours is appropriate to reverse life-threatening hyponatremic encephalopathy. 1, 2, 6 However, total correction must still not exceed 8 mmol/L in the entire 24-hour period. 1, 2, 4 This means if 6 mmol/L is corrected in the first 6 hours, only 2 mmol/L additional correction is permitted in the remaining 18 hours. 1
Monitoring Requirements
Check serum sodium every 2 hours during initial correction for severe symptoms, and every 4-6 hours for mild symptoms or asymptomatic patients. 1, 2 This frequent monitoring is essential to prevent inadvertent overcorrection, which commonly occurs due to unexpected water diuresis. 7
Management of Overcorrection
If sodium correction exceeds 8 mmol/L in 24 hours, immediately discontinue all sodium-containing fluids, switch to D5W (5% dextrose in water), and consider administering desmopressin to terminate water diuresis and relower sodium levels. 1, 2
Conflicting Evidence on Mortality
While traditional guidelines emphasize the 8 mmol/L limit to prevent osmotic demyelination syndrome 1, 2, 4, one recent meta-analysis suggests that slower correction rates may be associated with increased mortality. 8 However, the established guideline recommendation remains 8 mmol/L per 24 hours maximum, as osmotic demyelination syndrome is a severe and potentially irreversible complication. 1, 2, 4, 3, 5