Kidney function after radical nephrectomy: assessment by quantitative SPECT of 99mTc-DMSA uptake by the kidneys

To determine the function of the remaining contralateral kidney after the removal of a functioning kidney, 30 consecutive patients (18 men, 12 women; average age, 67 y; age range, 34-87 y) who were undergoing unilateral radical nephrectomy were evaluated by sequential quantitative 99mTc-dimercaptosuccinic acid (DMSA) SPECT (QDMSA) studies.

The 30 patients were undergoing radical nephrectomy for renal tumors. The first study was done before surgery. Follow-up studies were performed 2-23 mo after surgery. Clinical evaluations and determinations of serum creatinine level were performed at the same time as the QDMSA studies.

The relative contribution of the resected kidneys to the global renal function before surgery was 43.2% +/- 7.3%. After surgery the uptake of the remaining kidney increased from 13.4% +/- 4.0% to 18.3% +/- 5.8% (t = 5.7; P = 0.0000). The relative function of the remaining kidney increased from 56.8% +/- 7.1% to 79.1% +/- 23.6% (t = 4.9; P < 0.0001) of the global renal function before nephrectomy. Increases in the renal volume (from 211 +/- 62 cm3 to 229 +/- 68 cm3; t = 4.5; P = 0.0001) and in the percentage injected dose per cubic centimeter (%ID/cm3) of the remaining kidney (from 0.066 +/- 0.02 % ID/cm3 to 0.085 +/- 0.03 %ID/cm3; t = 4.6; P = 0.0001) were associated with this change. Nine patients had 2 follow-up studies performed 3-4 mo after surgery and 12-14 mo after surgery. The volume of the remaining kidney (209.22 +/- 46.20 cm3 versus 217.88 +/- 58.85 cm3; t = 0.962; P = 0.364), the %ID/cm3 (0.09 +/- 0.016 %ID/cm3 versus 0.093 +/- 0.025 %ID/cm3; t = 0.362; P = 0.726), and the percentage uptake (19.26% +/- 4.45% versus 20.11% +/- 7.01%) did not change significantly between these 2 QDMSA studies.

The results of this study suggest that adaptive changes causing hyperfunction of the remaining kidney may occur after nephrectomy of a functioning kidney in adults. These changes occur soon after surgery, persist for at least 1 y, and are evident on QDMSA studies.