Distribution of body potassium in healthy elderly subjects.

The whole body potassium content of a group of carefully screened, healthy, elderly subjects, mean age 73.5 years, has been accurately measured. The mean content was found to be approximately 10% lower than expected though there was a considerable range of individual values. Some of the interindividual variability could be reduced by taking into account body weight, height and in particular fat-free mass. The ratio of whole body potassium to fat-free mass (52.4 +/- 6.7 mmol/kg) was exceptionally low in this healthy group and showed no sex difference.