Radiopharmaceuticals for renal studies

A review of the wide spectrum of radiopharmaceuticals developed over the last 15 yr for application in the evaluation of diseases of the kidney and urinary tract is presented below. The radiolabeled contrast agents including Hippuran have been extensively applied for renal function assessment. The kinetics of clearance of many of these agents are not yet satisfactorily established, and there is no ideal agent for routine clinical application, particularly by external counting methods. Many agents for intrarenal blood flow measurement have been reported that have yet to be adapted for obtaining clinical information. Renal morphology has been studied using several radiopharmaceuticals that are either fixed in the renal tubules for a sufficiently long time (chlormerodrin, ^99mTc-Fe ascorbic acid) or cleared from the kidneys fairly rapidly (Hippuran). These agents suffer from several disadvantages because of suboptimum energy of the radiolabel for use with imaging equipment, or relatively high radiation dose, or slow rate of excretion with inadequate organ specificity. It is hoped that the development of new radiopharmaceuticals tagged with radionuclides that have ideal imaging characteristics (^99mTc or ¹¹¹In) and satisfactory renal clearances will provide a major breakthrough in the continuing search for satisfactory renal agents for imaging and function tests in the near future.