Total body potassium measurements in 230 patients. A study of potassium depletion.
Three groups of patients with suspected potassium depletion were studied. Twenty-nine obese patients were observed before and up to 1 year after an intestinal shunt operation. During the first week after operation they lost almost 3 grams of potassium per day. The percentage potassium loss was much larger than the percentage weight loss. A significant decrease of serum potassium was also noted during the first week after operation. In contrast to the total body potassium, however, the serum potassium remained within normal limits in all patients except two. Fourteen patients subjected to a cardiac operation also showed a significant decrease of total body potassium concentration 1 week after operation. The serum potassium remained within normal limits. In 187 patients with suspected potassium depletion the total body potassium had been measured, and the results were examined retrospectively. In 38 of these patients the measured total body potassium was outside a 94% confidence interval for an individually predicted value, even though 26 of these 38 patients were taking oral potassium chloride tablets. In 23 of these 38 patients two or three risk factors - hypoalbumin-emia, treatment with diuretics, and treatment with digitalis - were present simultaneously, and in 10 patients one factor was present. Only 8 of the 38 patients had a low serum potassium value. It may therefore be concluded that the total body potassium measurement, when compared with an individually predicted value, seems to be more sensitive in estimation of potassium depletion than the commonly used serum potassium method.