Clinical manifestations of hyponatremia include dysfunction of the central nervous system and are dependent on the severity and rate of development. For instance, the acute development of hyponatremia (<24 hours) as well as extremely low sodium concentrations (<120 mEq/L) may manifest with severe symptoms including confusion, agitation, delirium, lethargy, and seizures. The most common etiologies include syndrome of inappropriate antidiuretic hormone (SIADH), treatment with thiazide diuretics, polydipsia, and inappropriate administration of hypotonic intravenous fluids. Treatment consists of free-water restriction and, in severe cases, administration of hypertonic saline to correct the hyponatremia. To prevent central pontine myelinolysis, care must be taken to prevent too rapid a rise in serum sodium. This disorder results in quadriplegia and pseudobulbar palsy and is preventable with the judicious correction of serum sodium. The goal in patients with chronic hyponatremia and in asymptomatic patients should be a gradual correction of <10 mEq/L per 24 hours.