HYPONATREMIA IN AN ELDERLY PATIENT UNDER PAROXETINE THERAPY

A 77-year-old woman under paroxetine therapy developed mental confusio n due to hyponatremia. Findings were normal from thyroid function test s, tumor marker assays, a chest film, and laboratory tests for inflamm ation. There was no history of use of drugs known to induce hyponatrem ia. Excessive fluid intake was considered but fluid restriction proved ineffective. Because fluoxetine has been reported to induce hyponatre mia, paroxetine therapy was stopped. The clinical symptoms and laborat ory test abnormalities resolved within a few days. The rate of occurre nce of hyponatremia induced by serotonin recapture inhibitors (paroxet ine, fluoxetine, sertraline) is undoubtedly underestimated. Increased awareness of this adverse effect would avoid costly investigations and ensure rapid recovery via discontinuation of the drug.