Overcorrection of Hyponatremia: A Complicated Story.

Overcorrection is a frequently encountered issue in the treatment of severe hyponatremia, which is defined as a serum sodium concentration below 120-125 mmol/L in symptomatic patients. Severe hyponatremic symptoms, including persistent vomiting, cardiorespiratory arrest, seizures, and reduced consciousness, clearly indicate the use of hypertonic (e.g., 3%) saline infusion to immediately elevate serum sodium levels. In the chronic phase, however, overcorrection is a major concern because an overly rapid increase in serum sodium concentration is an important cause of osmotic demyelination syndrome (ODS). Although risk groups for ODS are well known, saline infusion and water diuresis are 2 common factors underlying the overcorrection of hyponatremia. We propose that isotonic saline initially be infused (1 mL/kg/h) when encountering hyponatremic patients with moderately severe symptoms, such as confusion, headache, or nausea. Although this empirical therapy may not be consistent with current guidelines, it may reduce the risk of overcorrection and be effective in cases with unrecognized hypovolemia or waning vasopressin hyperactivity. We believe that hypertonic saline should be reserved for patients with severely symptomatic hyponatremia. In practice, urine sodium and osmolality should then be measured, along with follow-up serum sodium levels. Subsequent intravenous fluids can be selected according to the response of serum sodium levels and the differential diagnosis of hyponatremia. Because water diuresis is a critical contributor to overcorrection, urine output and urine sodium, potassium, and osmolality should be monitored during fluid therapy. Appropriate use of 5% dextrose in water and/or desmopressin may be necessary to re-lower serum sodium levels.