Comparison of scintigraphic renal differentials using radiolabeled orthoiodohippurate and glucoheptonate

Differential renal blood flow and parenchymal mass were compared in 50 pairs of scintigraphic studies performed on 44 patients. Background corrected total kidney counts were determined between 1 to 2 minutes following injection of I-123 or I-131 orthoiodohippurate (OIH), and at 1 to 2.5 hours after injection of Tc-99m glucoheptonate (GHA). The OIH and GHA differentials agreed within 5% in 36 studies (72%). When the OIH differentials were symmetric (45% to 55% in each kidney), agreement with the GHA results was complete (17 out of 17). By comparison, 42% (14 out of 33) of studies with asymmetric OIH differentials had a greater than 5% disparity from the GHA split function. Serum creatinine was elevated at the time of 9 out of 14 studies (64%) with OIH/GHA disagreement and 18 out of 36 studies (50%) with OIH/GHA agreement. Of the 14 studies with disparate OIH/GHA differentials, the GHA differential was more symmetric in 10 (71%). When different scinitigraphic measures of differential renal flow and parenchymal mass disagree, this is most likely due to the effects of asymmetric renal impairment rather than to those of global renal dysfunction.