Objectives To evaluate the function of the remaining kidney after nephrectomy for renal cell cancer by technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3) renal scintigraphy. Methods We evaluated 30 consecutive patients who were undergoing unilateral radical nephrectomy by 99mTc-MAG3 scintigraphy. All patients underwent three consecutive 99mTc-MAG3 scintigraphy studies. The first study was performed before nephrectomy, the second 1 month after surgery, and the third 1 year after surgery. At these times, the serum creatinine levels were also evaluated. Results The mean preoperative MAG3 clearance of the remaining kidney of the 30 patients was 155.4 mL/min/1.73 m2. The mean MAG3 clearance of the remaining kidney had increased to 209.2 mL/min/1.73 m2 by 1 month after nephrectomy, and the average percentage increase was 39.5%. After 1 year, it had increased to 211.3 mL/min/1.73 m2, with a 40.5% average percentage increase. The preoperative MAG3 clearance of the remaining kidney was inversely correlated with the percentage of increase in MAG3 clearance of the remaining kidney. Abnormal serum creatinine levels (greater than 1.3 mg/dL) were more common after nephrectomy, occurring in 6 patients at 1 month and in 5 patients at 1 year postoperatively. In all 6 patients with elevated creatinine levels, the preoperative MAG3 clearance of the remaining kidney was less than 150 mL/min/1.73 m2. Conclusions Adaptive hyperfunction occurs soon after nephrectomy that is not associated with age or sex and continues for at least 1 year. A greater compensatory response is produced in patients with more severe renal deterioration. Using 99mTc-MAG3 scintigraphy, we may be able to predict postoperative renal function.
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