The renogram and individual 131I-hippuran clearances in experimentally controlled renal perfusion

The radioisotope renogram and renal clearances using 131I-Hippurate were studied during experimentally controlled renal perfusion. In the first series of experiments, renograms were recorded during variations in renal blood flow produced by an extracorporeal pump circuit. There was a close correlation between renal blood flow and renogram parameters. These characteristics were also related to urine flow rates. In the second series of experiments, unilateral renal damage was produced either by ischaemia or obstruction. Individual clearances using 131I-Hippurate and the gamma camera were compared with standard clearances obtained during a steady state. There was a close correlation between these methods and the results emphasise the importance of subtracting background radioactivity. It is concluded that the main value of the renogram is to provide a left to right comparison of renal tubular function whereas the value of corrected 131I-Hippuran clearances is to provide an absolute measure of individual effective renal plasma flow.