The Relationship of Total Exchangeable Potassium and Chloride to Lean Body

Potassium has long been known to be almost completely confined to the intracellular compartment, and the neutral fat present in muscle has been shown to have a low chloride content (1). It seemed probable, therefore, that the error associated with predictions of total exchangeable electrolyte from total body weight would diminish if the variable of depot fat was eliminated by the use of lean body mass as a reference standard. A close correlation of lean body mass with red cell mass (2) and urinary creatinine (3) has previously been shown. Accordingly, measurements of total exchangeable chloride and potassium have been correlated with lean body mass, red cell mass and creatinine excretion in a series of normal subjects.