MEASUREMENT OF RENAL-FUNCTION WITH TECHNETIUM-99M-MAG3 IN CHILDREN AND ADULTS

A single-injection, single-sample procedure for measuring Tc-99m-MAG3 clearance is presented that incorporates scaling for patient size and is valid for both children and adults. Methods: The procedure is based on an empirical formula in which all measurements are expressed in di mensionless combinations. The formula was obtained by fitting data col lected from 122 adults and 80 children at several centers. Results: Al l results were scaled to standard adult surface area and are presented in units of ml/min/ 1.73 m(2). For adult subjects, the residual stand ard deviation (r.s.d.) calculated from a single sample at 45 min was f ound to be 23, using the plasma clearance calculated from a multi-samp le clearance curve as a reference. This did not differ significantly f rom the value of 22 obtained with our previous formula, which was vali d for adults only. for pediatric subjects, an r.s.d. of 24 was calcula ted by the new formula from a single sample at 35 min; a comparable va lue of 33 was found using a pediatric formula previously published. Co nclusion: The new clearance formula is recommended as a replacement fo r the formula we previously published, since it is based on a larger a nd more diverse subject population, and since it now holds for childre n as well, with no loss of accuracy for adult subjects.