[Electrolyte abnormalities in elderly people. Prevalence and relation to drug treatment. Multicenter study of 631 subjects aged 70 years and over].

In order to assess the responsibility of medicinal drugs for the disorders in electrolytes observed in elderly people, the prevalence of abnormal natraemia and kalaemia was prospectively established in 631 subjects aged 70 or more on the first day of hospitalization. Among 337 subjects not taking drugs likely to create problems (diuretics, angiotensin-converting enzyme inhibitors, anti-inflammatory agents) 3.6 percent had hyponatraemia (below 130 mmol/l) and 12.2 percent had hypokalaemia (below 3.5 mmol/l). Subjects with normal renal function who were taking angiotensin-converting enzyme inhibitors or non-steroidal anti-inflammatory agents showed no more electrolytic abnormalities than those who did not take them. Conversely, subjects on thiazides were more frequently hyponatraemic (11.8 percent) or hypokalaemic (16.2 percent; 20 percent in the absence of associated distal diuretics). These abnormalities were more frequent in women than in men (21.7 and 13 percent). This, together with the fact that 68 percent of subjects taking thiazides were women accounts for the marked female predominance of electrolytic abnormalities reported in the literature.