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Who is at risk for Osmotic demyelination syndrome (ODS)?
Patients with acute hyponatremia developing over less than 24 to 48 hours are at low risk for Osmotic demyelination syndrome, and there is accordingly no potential for harm in rapid correction of hyponatremia in this group.
Osmotic demyelination syndrome is also unlikely to arise as a complication of treatment in patients presenting with a serum sodium >125 mEq/L.
Conversely, an initial serum sodium <105 mEq/L, hypokalemia, alcoholism, malnutrition, and advanced liver disease are risk factors for Osmotic demyelination syndrome in patients with chronic hyponatremia.
Strategies for sodium correction aimed at preventing ODS are outlined in the below table.
Notably, hyponatremia should be assumed to be chronic and managed as such unless its onset is clearly known to be <48 hours.
Goals and Limits for Treatment of Hyponatremia Stratified by Duration and Risk of Osmotic Demyelination Syndrome
| PRESENTATION | RISK For ODS | GOAL INCREASE In [Na + ] | LIMIT TO INCREASE IN [Na + ] | TREATMENT STRATEGY |
|---|---|---|---|---|
| Acute Hypotonic Hyponatremia (duration verified to be <48 h) | ||||
| Severe symptoms | Negligible | Rapid increase by 4–6 mEq/L, then gradual increase to normalization | None | Rapidly increase serum Na by 4–6 mEq/L with up to three 100 mL boluses of hypertonic saline given over 10 min at a time, followed by hypertonic saline at 1 mL/kg/h until substantial normalization |
| Mild or moderate symptoms | Negligible | Normalization | None | Fluid restriction alone if etiology rapidly reversible. Otherwise, hypertonic saline at 1 mL/kg/h until substantial normalization |
| Chronic Hypotonic Hyponatremia (duration known to be >48 h or duration uncertain) | ||||
| Severe, moderate, or mild symptoms | High a | 4–6 mEq/L in 24 h | 8 mEq/L in any 24 h period | Treatment according to etiology (e.g., volume repletion for hypovolemic hyponatremia, water restriction with SIADH or hypervolemic hyponatremia) and severity of symptoms. Can consider hypertonic saline for severely symptomatic euvolemic hyponatremia with risk of seizures or herniation or a vaptan for mild-to-moderate, refractory euvolemic or hypervolemic hypernatremia. Closely monitor [Na + ] every 2–4 h and urine output. Re-lower [Na + ] with IV 5% dextrose or enteral water ± desmopressin 1–2 mcg Q6 h if overly rapid correction |
| Severe, moderate, or mild symptoms | Intermediate | 4–8 mEq/L in 24 h | 10–12 mEq/L in any 24 h and no more than 18 mEq/L in any 48 h period | Same strategy as high-risk ODS patients, except with less strict [Na + ] correction goals and limits |
| Moderate or mild symptoms | Low (initial [Na + ] > 125 mEq/L) | Normalization | Normalization | Treatment according to etiology. Can consider vaptan for mild-to-moderate, refractory euvolemic or hypervolemic hypernatremia |
In patients with significant risk of ODS, especially those with starting [Na + ] <120 mEq/L, who experience a rise in [Na + ] exceeding recommended limit, consider re-lowering [Na + ] to a value below target by administration of electrolyte-free water. Urine output and/or osmolality should also be followed to detect onset of a spontaneous water diuresis (volume depletion, thiazide-associated) that can lead to overly rapid correction. Desmopressin may be useful in this setting to limit ongoing urinary water loss.IV, Intravenous; [Na + ] , serum sodium concentration; ODS , osmotic demyelination syndrome; SIADH , syndrome of inappropriate antidiuretic hormone secretion.
a [Na + ] ≤105 mEq/L, hypokalemia, alcoholism, malnutrition, advanced liver disease.
