Estimate of relative function and transit time in renographic studies.

Renal transit time and relative renal function are the most commonly used parameters in the study of renal function. In clinical practice the determination of these two parameters is carried out either using the renal retention function or directly from the renogram. This study seeks to compare the values for the transit time and the relative function, as calculated from the renogram and from the renal retention function, in renographic studies using 131I-OIH and 99mTc-MAG3. For both tracers it was found that the estimated renal transit time from the renogram (OIH: 289 +/- 118 s, MAG3: 297 +/- 110 s) generated values that were higher than those obtained from the renal retention function (OIH: 245 +/- 85 s, MAG3: 274 +/- 97 s), with significant differences between the two estimates (p < 0.001). As regards the relative function, there were no significant differences between the estimates obtained from the renogram (58.5 +/- 8.3%) and the renal retention function (59.5 +/- 9.3%) in the case of OIH. For MAG3 the estimate obtained from the renogram (58.3 +/- 6.3%) and from the renal retention function (59.9 +/- 7.1%) were significantly different (p < 0.025).