Use of Radionuclides to Study Renal Function

Radionuclides have been used to study renal function clinically since the introduction of the radioisotope renogram by Taplin (1 ) and Kimball (2 ). This use is mainly directed at the excretory functions of the kidney that involve glomerular filtration and tubular secretion. Glomerular filtration is a process that may be quantified by the measurement of the rate of renal clearance of a particular substance in the blood. The indicator must meet the following criteria: i) free filtration through the glomerular capillary membranes; ii) no secretion or absorption by the renal tubules; iii) no metabolism by the kidney; iv) no binding to plasma proteins; v) nontoxic and inert; and vi) measurable with high accuracy. Radiochemical purity is an additional requirement when radiolabeled agents are used.