Tc-99m Hydroxymethylene Diphosphonate (HMDP) Renal Uptake as a Surrogate Marker of Postoperative Impairment of the Glomerular Filtration Rate in Renal Tumor Patients Following Nephron-Sparing Surgery

Purpose: We investigated Tc-99m hydroxymethylene diphosphonate (HMDP) scintigraphy findings in renal tumor patients from the perspective of postoperative renal dysfunction following nephron-sparing surgery (NSS). Methods: Forty-three renal tumor patients (M:F = 28:15, age 53.9 ± 12.5 years) who had undergone Tc-99m HMDP scintigraphy after NSS were enrolled. The patients were divided into HMDP⁺ or HMDP⁻ groups by visual assessment, and the asymmetric index (ASI) was calculated using a region-of-interest analysis. In 16 patients, the total and split glomerular filtration rate (GFR) was assessed using Tc-99m diethylenetriaminepentaacetic acid (DTPA) scintigraphy at baseline and at 3 and 6 months post-NSS. Results: High Tc-99m HMDP uptake was observed in the operated kidneys, but this did not persist later than 7 days post-NSS. Split GFR of the operated kidneys at baseline (58.5 ± 9.3 ml/min) was significantly reduced at 6 months post-NSS (40.1 ± 5.9 ml/min, p < 0.001) in only those who showed intense uptake of Tc-99m HMDP. Declines in both total GFR (p = 0.010 and p = 0.002 for 3 and 6 months, respectively) and split GFR of the operated kidneys (p < 0.001 and p < 0.001 for 3 and 6 months, respectively) were clearly evidenced at 3 and 6 months post-NSS only in patients with high Tc-99m HMDP in the operated kidneys. The ASI was negatively correlated with %change in the split GFR of these operated kidneys at 6 months post-NSS (rho =−0.578, p = 0.0304). Conclusions: Tc-99m HMDP uptake within 1 week following NSS is a surrogate marker of GFR impairment over 6 months post-NSS.