Clinical comparison of Tc-99m N,N'-bis(mercaptoacetamido)ethylenediamine and [131I]ortho-iodohippurate for evaluation of renal tubular function: concise communication.

Recent experiments in normal animals have shown that Tc-99m N,N'-bis(mercaptoacetamido)ethylenediamine (Tc-99m DADS) is a potential technetium-99m-labeled replacement for [131I]ortho-iodohippurate(I-131 Hipp). We compared the two agents in eleven patients with renal transplants (serum creatinine range: 0.9--5.7 mg/dl). Digital and analog images were recorded for 30 min and after voiding. The results indicate that the relative extraction efficiency index of Tc-99m DADS is 76% +/- 3 (mean +/- s.e.m.), that the leading-edge parenchymal transit time of Tc-99m DADS is 137% +/- 6, and that the percentage of injected Tc-99m DADS in the bladder at 30 min is 25% +/- 4 of that of I-131 Hipp (all p less than 0.05). Forty percent of patients showed some hepatobiliary excretion of Tc-99m DADS. We conclude that the biologic properties of Tc-99m DADS are inferior to those of I-131 Hipp and that analogs of Tc-99m DADS should be evaluated in an attempt to find a more suitable technetium-99m-labeled replacement for I-131 Hipp.