Errors in potassium balance.

ABSTRACT

Six overweight adult subjects given a low calorie diet containing adequate amounts of nitrogen but subnormal amounts of potassium (K) were observed on the Clinical Research Center for periods of 29 to 40 days. Metabolic balance of potassium was measured together with frequent assays of total body K by 40K counting. Metabolic K balance underestimated body K loses by 11 to 87% (average 43%); the intersubject variability is such as to preclude the use of a single correction value for unmeasured losses in K balance studies.