Hypokalemia: are elderly females more vulnerable?

This study was undertaken to evaluate the relationship between prevalence of hypokalemia and the age and sex of patients. Serum potassium concentrations of 872 patients were measured, and the prevalence of hypokalemia was compared between age and sex groups. Hypokalemia was more common in patients 65 years or older than in younger groups (P < .001), with a significantly higher frequency in female patients (P < .003). The finding was more common in elderly female patients than in elderly males (P < .002). No statistically significant difference was noted in the frequency of hypokalemia in elderly male patients compared with younger patients of either sex. The predominance of hypokalemia in elderly groups was chiefly attributable to a marked preponderance in elderly female patients over all other groups. Neither younger females nor elderly males were at increased risk. The preponderance in elderly females was not dependent on diuretic usage. It may have been due to age- and sex-associated differences in body mass composition, which result in a physiologically low total exchangeable body potassium in elderly females, placing this group at greater risk for developing hypokalemia.