Hyponatraemia in hospitalised elderly patients.

This study aims to investigate the incidence and causes of hyponatraemia in hospitalised elderly patients. There was a total of 407 new patients. 55 (13.5%) patients were found to have at least one episode of hyponatraemia during their hospitalization. There were 58 deaths. Fifteen out of 55 (27.3%) patients who had hyponatraemia died compared to 43 out of 352 (12.2%) normonatraemic patients (chi-square significant, p < 0.01). The three most common causes of hyponatraemia were syndrome of inappropriate antidiuretic hormone secretion (SIADH), poor oral intake and diuretics. The two most common causes of SIADH were lower respiratory tract infection and stroke.