From the Guidelines
The goal rate of correction of hyponatremia should not exceed 8 mEq/L per 24-hour period, with a more conservative approach of 4-6 mEq/L per 24 hours for patients at high risk of Osmotic Demyelination Syndrome (ODS), as recommended by recent guidelines 1.
Background
Osmotic Demyelination Syndrome (ODS) is a rare but potentially life-threatening complication of rapid correction of hyponatremia. The risk of ODS is increased in patients with advanced liver disease, alcoholism, malnutrition, and severe metabolic derangements.
Recommendations
- For patients with chronic hyponatremia, the goal rate of correction should not exceed 8 mEq/L per 24-hour period, with a more conservative approach of 4-6 mEq/L per 24 hours for patients at high risk of ODS 1.
- Patients at high risk of ODS include those with advanced liver disease, alcoholism, malnutrition, and severe metabolic derangements, such as hypokalemia, hypophosphatemia, or hypoglycemia 1.
- If overcorrection occurs, prompt relowering of serum sodium using hypotonic fluids (D5W or hypotonic saline) and/or desmopressin (DDAVP) at doses of 2-4 mcg IV/SC every 6-8 hours is recommended 1.
- Monitoring serum sodium levels every 2-4 hours during active correction is essential to prevent overcorrection and reduce ODS risk.
Pathophysiology
The pathophysiology behind these recommendations relates to the brain's adaptation to chronic hyponatremia through loss of organic osmolytes, which takes time to reverse during correction. Rapid correction doesn't allow sufficient time for the brain to readapt, leading to osmotic stress and potential demyelination.
Clinical Considerations
- The use of vasopressin receptor antagonists, such as vaptans, may be considered for the treatment of euvolemic hyponatremia, but should be used with caution and only for a short term (≤30 days) 1.
- The use of hypertonic saline is reserved for short-term treatment of patients with symptomatic or severe hyponatremia or those with imminent liver transplant (LT) 1.
- Multidisciplinary, coordinated care may mitigate the risk of ODS, and LT need not be prohibited by hyponatremia alone 1.
From the Research
Osmotic Demyelination Syndrome (ODS) and Hyponatremia Correction Rate
- The rate of correction of hyponatremia is a critical factor in preventing Osmotic Demyelination Syndrome (ODS) 2, 3, 4, 5, 6.
- A recent meta-analysis found that rapid correction of serum sodium may increase the risk of ODS among patients hospitalized with severe hyponatremia, but it also reduces the risk of in-hospital mortality and length of stay 4.
- Another systematic review and meta-analysis found that slow correction and very slow correction of severe hyponatremia were associated with an increased risk of mortality and hospital length of stay compared to rapid correction 6.
Recommended Correction Rates
- The recommended rate of correction of hyponatremia varies depending on the severity and duration of the condition:
- Acute hyponatremia: rapid correction at a rate of at least 1 mmol/L/hour 3.
- Chronic hyponatremia: slow correction at a rate of less than 0.5 mmol/L/hour 2, 3, 5.
- Severe symptomatic hyponatremia: rapid correction during the first few hours followed by a slow correction limited to 10 mmol/L over 24 hours 5.
Clinical Outcomes
- Rapid correction of severe hyponatremia has been associated with improved clinical outcomes, including reduced in-hospital mortality and length of stay 4, 6.
- However, rapid correction also increases the risk of ODS, which can be severe and potentially life-threatening 4.
- Slow correction and very slow correction of severe hyponatremia have been associated with increased mortality and hospital length of stay 6.