Sodium Overcorrection in Hyponatremia
Maximum Correction Rate
The maximum correction rate for sodium in hyponatremia should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome (ODS), with high-risk patients requiring even more cautious correction at 4-6 mmol/L per day. 1
Standard Correction Guidelines
For Average-Risk Patients
- Target correction rate: 4-8 mmol/L per day 1
- Absolute maximum: Do not exceed 10-12 mmol/L in 24 hours 1
- 48-hour limit: Maximum 18 mmol/L over 48 hours 2
For High-Risk Patients
High-risk patients require slower correction rates of 4-6 mmol/L per day, with an absolute maximum of 8 mmol/L in 24 hours 1. High-risk features include:
- Advanced liver disease or cirrhosis 1
- Chronic alcoholism 1, 3
- Malnutrition 1, 3
- Prior encephalopathy 1
- Severe hyponatremia with initial sodium <115 mmol/L 3
- Hypokalemia 3
- Hypophosphatemia 1
Severe Hyponatremia Considerations
For patients with serum sodium <115 mmol/L, osmotic demyelination syndrome can occur even with correction rates ≤10 mmol/L per 24 hours 3. In these patients, limit correction to <8 mmol/L in 24 hours 3.
Among patients with severe hyponatremia (<115 mmol/L) who developed ODS despite guideline adherence, the maximum correction rate was at least 8 mmol/L in all but one patient, suggesting that even 8 mmol/L may be too rapid for this population 3.
Acute Symptomatic Hyponatremia Exception
For severe symptomatic hyponatremia (seizures, coma, altered mental status), initial rapid correction is warranted:
- Target: Increase sodium by 6 mmol/L over the first 6 hours or until symptoms resolve 1
- Critical limit: Total correction must still not exceed 8 mmol/L in 24 hours 1
- Calculation: If 6 mmol/L corrected in first 6 hours, only 2 mmol/L additional correction allowed in next 18 hours 1
This approach balances the need to reverse life-threatening cerebral edema against the risk of osmotic demyelination 4.
Managing Overcorrection
If sodium correction exceeds 8 mmol/L in 24 hours, immediate intervention is required 1:
- Discontinue current fluids immediately and switch to D5W (5% dextrose in water) 1
- Administer desmopressin to slow or reverse the rapid rise in serum sodium 1, 5
- Goal: Relower sodium to bring total 24-hour correction to ≤8 mmol/L from starting point 1
The combination of hypertonic saline with concurrent desmopressin administration can prevent inadvertent overcorrection by controlling water diuresis 5.
Monitoring Requirements
Severe Symptoms
- Check serum sodium every 2 hours during initial correction phase 1
- Continue every 2-hour monitoring until symptoms resolve 1
Mild Symptoms or Asymptomatic
- Check serum sodium every 4 hours after symptom resolution 1
- Transition to every 24 hours once stable 1
Osmotic Demyelination Syndrome
ODS typically occurs 2-7 days after rapid correction and presents with 1:
- Dysarthria (difficulty speaking)
- Dysphagia (difficulty swallowing)
- Oculomotor dysfunction
- Quadriparesis
- Parkinsonism 4
The mortality rate from ODS is approximately 19%, with only 24% achieving full recovery and 42% having residual neurologic deficits 3.
Critical Pitfalls to Avoid
- Never correct chronic hyponatremia faster than 8 mmol/L in 24 hours - this is the single most important safety limit 1, 4
- Never assume 10-12 mmol/L is safe for high-risk patients - use 4-6 mmol/L per day instead 1
- Never ignore initial sodium <115 mmol/L - these patients require maximum caution with correction <8 mmol/L per day 3
- Inadequate monitoring during active correction is a common pitfall that leads to overcorrection 1
- Failing to recognize high-risk features (alcoholism, malnutrition, liver disease) leads to inappropriately rapid correction 1, 3