Excretion Urography: I—Factors Determining the Excretion of Hypaque

Abstract

The development of a simple method for the chemical analysis of sodium diatrizoate has permitted the investigation of the factors affecting the renal excretion of 45% Hypaque in normal subjects and in patients undergoing routine IVP. The study has shown that the amount of Hypaque excreted in unit time is a function of the GFR and the plasma concentration at that time. The rate of excretion is maximal in the first 10–20 minutes following the injection of medium and follows the rise and fall in plasma concentration. The ten-minute plasma concentration has been shown to be a function of dose and is readily and accurately reproducible. Studies of the urinary concentration of Hypaque have shown that despite prior claims to the contrary, increasing doses up to 0·75 ml./lb. body weight are associated not only with increasing urine flow but also increased concentration of contrast media in the urine. It has been shown that the concentration of Hypaque in the urine was markedly affected by the state of hydration even with such high dosage. The interrelation between the plasma and urine concentration of Hypaque, the GFR and the rate of urine flow in determining the rate of excretion of Hypaque is discussed. A clear understanding of these factors is an essential basis for the production of high-quality urographic examinations.