Treatment of hyponatremia

Abstract

Treatment of hyponatremia must meet three goals: (1) make sure the plasma sodium concentration does not decrease any further, (2) increase the plasma sodium concentration enough to prevent complications from the untreated electrolyte disturbance, and (3) avoid iatrogenic neurological injury caused by an excessive increase in the plasma sodium concentration. Patients with self-induced water intoxication and hospital-acquired hyponatremia may experience an unexpected fall in serum sodium due to delayed absorption of ingested water or “desalination” of previously administered intravenous fluids. These conditions are associated with a high risk of seizures and rarely death from cerebral edema. A 4–6 mEq/L increase in serum sodium concentration is enough to improve the most severe symptoms in patients with acute hyponatremia. Patients with severe chronic hyponatremia are at risk of iatrogenic brain damage (osmotic demyelination syndrome) caused by excessive correction of the electrolyte disturbance. Because an unexpected water diuresis often leads to inadvertent overcorrection, it is wise to limit the increase in serum sodium concentration to 6 mEq/L/day, even in patients with extremely low serum sodium.