Total body potassium, muscle electrolytes, and glycogen in malnourished children

Total body potassium, muscle potassium, magnesium, and glycogen have been estimated in infants while they were malnourished, during recovery, and in several after they were fully recovered. Muscle potassium was curvilinearly related to the total body potassium. Muscle magnesium was reduced, and the potassium/magnesium ratio was depressed in children with low muscle potassium values, implying differential loss of muscle potassium. Muscle potassium was linearly related to muscle glycogen. Twenty-four-hour urinary excretion of creatinine was measured; by assuming that 1 mg. of creatinine was derived from 20 Gm. of muscle, calculations of muscle mass were made. In children with a total body potassium over 40 mEq. per kilogram of body weight, muscle potassium contributed approximately one half of the total body potassium; this ratio decreased significantly when body potassium fell to very low values.