Double Isotope Technique to Measure Renal Functions:  Single Injection Technique Without Urine Collection

THE NEED for both total and separate renal functions for diagnosis and therapy requires a method of testing which is accurate, reasonably simple, and not hazardous to the patient. Present techniques require anesthesia and introduction of catheters into the bladder or ureters and are time consuming.

This paper reports a technique in which is utilized I¹²⁵- and I¹³¹-labeled compounds to measure glomerular filtration rate and renal blood flow simultaneously without urine collection. Iodine I¹³¹ and I¹²⁵ were used because they are readily available in the triiodinated benzoate analogues used as contrast media for intravenous pyelography and their physical properties enable accurate counting in mixtures.

Methods 

Double Labeling with I125 and I131.—  Double labeling with radioactive isotopes consists of using two different radioactive isotopes of the same element, in different chemical forms, with the purpose of analyzing separately the two compounds, using the