The Relationship of Total Exchangeable Potassium and Chloride to Lean Body Mass, Red Cell Mass and Creatinine Excretion in Man

Abstract

A comparison of various reference standards for total exchangeable potassium (Ke) and chloride (Cle) was carried out in 16 normal males and 14 normal females. The use of total body weight as a standard of reference for Ke and Cle was unsatisfactory, the 95% confidence limits being [plus or minus]53% and [plus or minus] 29% of the mean respectively, and an apparent sex difference based on this reference standard was shown to be due to the greater fat content of the female subjects. A closer relationship existed between Ke and (1) lean body mass (95% confidence limits [plus or minus] 25%) and (2) red cell mass (95% confidence limits [plus or minus] 25%) and (3) 24-hour urinary creatinine (95% confidence limits [plus or minus] 28%). An even closer relationship of Cle with lean body mass and red cell mass was found, the 95% confidence limits being [plus or minus] 14% and [plus or minus] 15% respectively. The correlation of Cle with urinary creatinine was no better than with total body weight. These relationships held for both males and females throughout wide ranges of age and body weight.