Can body potassium of old people be predicted from anthropometric data?

Body potassium was measured by whole body counting in a group of carefully screened healthy individuals, mean age 75 years. The results have been compared with values predicted by eight formulae in the literature derived using similar methods. The mean predicted results ranged from 87% to 102% of the mean observed level in male subjects and from 87% to 137% in female subjects. Individual male results range from 55% to 123% and in female subjects from 72% to 146% of the observed value. It is concluded that there are no published formulae which will adequately predict whole body potassium levels in old people--the very group likely by virtue of age-related disease, to need measurements of body potassium.