Evaluation of separate renal function by means of 99mTc-aprotinin uptake test

The possibility that relative kidney uptake of technetium-99m aprotinin (TcA) might be indicative of separate renal function was investigated in 89 patients who underwent both effective renal plasma flow (ERPFs) and glomerular filtration rate (GFR) determination. A reference group consisted of 27 healthy volunteers, studied only with TcA. The correlation with ERPFs (r = .73) was similar to that previously reported and confirmed. The correlation with GFR (r = .68) was better if a subgroup of renal units with TcA uptake lower than 16% (lower normal limit) was considered. Most likely, glomerular filtration is a limiting factor of the tubular uptake of TcA, and when GFR is reduced, both parameters decrease in the same manner, while if GFR is normal the two parameters are relatively independent. The correlation between TcA and GFR in 32 children was very similar to that found in adults. TcA uptake test seems to be a useful indicator of separate renal function, providing morphological information at, the same time.