Maximum Rate of Sodium Correction in Hyponatremia
The maximum rate of sodium increase should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1
Standard Correction Limits
For most patients with hyponatremia, the safe correction targets are:
- Maximum 8 mmol/L in the first 24 hours 1, 2
- Maximum 18 mmol/L in 48 hours 3
- Maximum 20 mmol/L in 72 hours 3
These limits represent the absolute ceiling to avoid osmotic demyelination syndrome, a potentially devastating neurological complication. 1, 2
Recommended Conservative Targets
Rather than pushing to the maximum limits, safer therapeutic goals are:
This approach keeps patients safe from both hyponatremia complications and iatrogenic injury from overcorrection. 3
High-Risk Populations Requiring Slower Correction
Certain patients require even more cautious correction at 4-6 mmol/L per day, not exceeding 8 mmol/L in 24 hours: 1
- Advanced liver disease or cirrhosis 1
- Chronic alcoholism 1
- Malnutrition 1
- Prior hepatic encephalopathy 1
- Severe baseline hyponatremia (<120 mmol/L) 1
- Hypophosphatemia, hypokalemia, or hypoglycemia 1
These patients have a significantly higher risk of osmotic demyelination syndrome (0.5-1.5% in liver transplant recipients), making conservative correction essential. 1
Exception: Severe Symptomatic Hyponatremia
For patients with life-threatening symptoms (seizures, coma, altered consciousness, respiratory distress), initial rapid correction is appropriate: 1, 2
- Correct by 4-6 mmol/L over the first 6 hours or until severe symptoms resolve 1, 4
- Use 3% hypertonic saline as bolus infusions 1, 2
- Still maintain the 8 mmol/L limit for the entire 24-hour period 1, 5
This means if you correct 6 mmol/L in the first 6 hours, only 2 mmol/L additional correction is allowed in the remaining 18 hours. 1
Chronic vs. Acute Hyponatremia
The duration of hyponatremia critically affects safe correction rates:
- Chronic hyponatremia (>48 hours): Maximum 8 mmol/L per 24 hours, with 4-6 mmol/L per day preferred for high-risk patients 1
- Acute hyponatremia (<48 hours): Can tolerate more rapid correction without osmotic demyelination risk, but still requires careful monitoring 1
The brain adapts to chronic hyponatremia by extruding osmolytes, making rapid correction particularly dangerous. 2
Critical Monitoring Requirements
To avoid inadvertent overcorrection:
- Check serum sodium every 2 hours during initial correction for severe symptoms 1
- Check every 4 hours after symptom resolution 1
- Monitor for unexpected water diuresis, which commonly causes overcorrection 3, 5
- Track urine output closely 3
Management of Overcorrection
If sodium correction exceeds 8 mmol/L in 24 hours: 1
- Immediately discontinue current fluids and switch to D5W (5% dextrose in water) 1
- Consider administering desmopressin to slow or reverse the rapid rise 1, 3, 5
- The goal is to bring total 24-hour correction back to ≤8 mmol/L from the starting point 1
Using desmopressin concurrently with hypertonic saline from the start can prevent inadvertent overcorrection by controlling water diuresis. 5
Common Pitfalls
Avoid these errors that lead to osmotic demyelination:
- Exceeding 8 mmol/L correction in 24 hours, particularly in high-risk patients 1
- Failing to account for spontaneous water diuresis after treating the underlying cause 3
- Inadequate monitoring during active correction 1
- Using correction rates >1 mmol/L per hour except in acute severe symptomatic cases 1
Even mild overcorrection can cause osmotic demyelination syndrome, which typically manifests 2-7 days after rapid correction with dysarthria, dysphagia, oculomotor dysfunction, and quadriparesis. 1