Total body potassium and serum potassium among eating disorder patients

The purpose of the study was to determine body composition, including total body potassium (TBK+), serum potassium, and lean body mass (LBM), in anorexia nervosa. TBK+ measurements, serum potassium levels, and anthropometric measurements were obtained from four anorectic patients in the first week after their hospital admission. All four patients had normal serum potassium levels but three of the four had significant depletion of total body potassium. Two methods of calculating LBM, based on TBK+ measures or anthropometric assessment, produced different results. TBK+ may be depleted even when serum potassium levels are normal. It was also concluded that the two methods of calculating LBM were inaccurate. Patients may be at risk for cardiac arrhythmias and other physiological abnormalities even when serum potassium is normal since TBK+ may be low. The need for comprehensive assessment of body composition based on four compartment models is discussed