Whole-body and exchangeable potassium measurements in normal elderly subjects

A comparison of total body potassium status of eighteen healthy subjects with normal renal function in the age group 65-85 years, measured by whole body counting and by total exchangeable potassium on plasma and urine samples taken at 24h, shows that there is no delay in exchange in radioactive potassium in the elderly, and that the exchangeable method gives a reliable value of total body potassium. The results suggest that the normal range for potassium per kilogramme body weight is lower for old persons than for younger age groups.