Effect of Water Diuresis on Renal Excretion of Certain Urinary Solutes in Normal Man

Abstract

Changes in the renal excretion of CO2, Na, K, chloride, urea, and phosphate following standard water loads of 50 cc. and 25 cc./kg. were studied in 3 normal fasting young subjects. Endogenous creatinine clearances were obtained as a relative measure of glomerular filtration rate. pH of the urine was measured at each collection period. The clearance ratio of total CO2 was found to be directly proportional to the clearance ratio of water, with a high statistical correlation (r = 0.02, P <0.001). The urinary pH was independent of the diuresis and the CO2 excretion, and remained relatively constant. Urea and phosphate clearance ratios rose during great or sudden rise in diuresis, but did not vary constantly with the clearance ratio of water. K, Na and chloride excretion fell considerably 3 hrs. after water admn. Water diuresis induces changes in the excretion of urinary solutes of some magnitude. These changes might obscure or modify the results of expts. performed after diuresis has been promoted by water ingestion.