SIMPLE TECHNIQUE FOR MEASURING RELATIVE RENAL BLOOD-FLOW

Abstract

To determine whether externally monitored early renal uptake of 131I-hippurate is proportional to renal blood flow, the renal uptake of 131I-hippurate at 1-2 min after injection was compared with the renal accumulation of radioactive carbonized microspheres in dogs. A renal artery catheter equipped with a balloon was used to decrease renal blood flow unilaterally. One minute after the i.v. injection of 100 .mu.Ci of 131I-hippurate, about 1 .mu.Ci of either 85Sr- or 95Nb-labeled C microspheres was injected into the left ventricle. Radioactivity was measured over both kidneys. The total radioactivity within each kidney region of interest was corrected for background and integrated over the 1-2 min interval after injection. Thirteen measurements of relative renal blood flow were made for 7 dogs. The dogs were then killed and both kidneys were excised and counted for the radioactivity of the microspheres. The 1-2 min relative renal uptake of 131I-hippurate correlated well with relative microsphere uptake, suggesting that relative renal blood flow can be simply determined from the external measurement of renal uptake of 131I-hippurate. [Abolute and relative renal blood flow measurements are of clinical value in screening hypertensive patients for renovascular disease and in determining the type of urologic surgery for patients with asymmetric renal disease.].