The Renal Excretion of Potassium.∗

Discussion and Conclusions K clearances in excess of creatinine or thiosulfate clearances, under the conditions of these experiments, are interpreted as- evidence that all of the K excreted in the urine cannot be accounted for by the nltration-reabsorption theory alone, but that tubular secretion of K also occurs. In the experiments on urea diuresis, urea clearances never exceeded creatinine clearances, and the ratios agreed with the observations of Shannon. 8 It is a reasonable hypothesis that during urea diuresis the secretion of K becomes apparent because its normal tubular reabsorption is hindered. The present data are insufficient to define the mechanisms involved in the secretory process or to demonstrate the relative magnitude of the processes of filtration, reabsorption and secretion in the renal excretion of K. Further work is in progress.