The Syndrome of Inappropriate Antidiuresis

A 62-year-old woman who reported dysgeusia was found to have a serum sodium level of 122 mmol per liter. The serum osmolality was 250 mOsm per kilogram of water, and the urinary osmolality 635 mOsm per kilogram of water. Chest CT showed a mass in the lower lobe of the left lung, which proved to be a small-cell carcinoma. How should her hyponatremia be treated?