Older Age and In-Hospital Development of Hypokalemia From Loop Diuretics: Results From a Multicenter Survey

Background. Hypokalemia is a common finding among older patients taking diuretic medications. However, it is not known whether older age per se carries an increased risk of hypokalemia, particularly during a patient's treatment with loop diuretics. Methods. The association between age and incident hypokalemia was examined in 18,872 patients with normal baseline serum potassium enrolled during three yearly multicenter surveys; 4,035 patients started receiving loop diuretics during their hospital stay. Demographic variables, comorbid conditions, medications, and objective tests that were associated with incident hypokalemia in separate age- and sex-adjusted logistic regression models were examined as potential confounders. Results. Among patients with normal baseline serum potassium, the factors of age, presence of coronary disease or diabetes, comorbidity, the use of ACE inhibitors, loop diuretics, digitalis, corticosteroids, or insulin, and baseline serum potassium were associated with incident hypokalemia in initial models. After these variables were adjusted for, age (for each decade, odds ratio = 1.30; 95% confidence interval = 1.17-1.46; p < .0001) was associated with incident hypokalemia. The use of parenteral (2.30; 1.53-3.46; p < .0001) but not oral (1.16; 0.79-1.69; p = .44) loop diuretics was associated with hypokalemia. Eventually, age was associated with hypokalemia when the summary regression model was analyzed in patients taking loop diuretics (1.33; 1.03-1.71;p = .027), as well as in those taking intravenous loop diuretics only (1.84; 1.25-2.70; p = .002). Conclusions. Older age is independently associated with the in-hospital development of hypokalemia, particularly among patients taking loop diuretics. Monitoring of serum potassium levels is therefore advisable when older patients are treated with these agents.