The kidney that received the greater mean kidney dose was defined as the primarily irradiated kidney. The kidney that received the lesser mean kidney dose was defined as the non-primarily irradiated kidney. All patients received concurrent chemotherapy. Few patients received chemotherapy prior to radiation and most patients received further chemotherapy following radiation.

Renal scintigraphy All patients received intravenous hydration prior to intravenous injection of 6 mCi of Technetium99m MAG-3. Renal scintigraphy was performed with the patient in the supine position Inhibitors,research,lifescience,medical and images were obtained in the posterior projection. Sequential flow images were obtained for quantitative analysis of the renogram, initially taken as 1 second per frame for the first minute and then as 30 seconds per frame for the next 30 minutes. The posterior images were obtained using a 64 x 64 matrix on a large field of view gamma camera with low energy collimators. Inhibitors,research,lifescience,medical Split uptake of left to right relative function was measured over the initial 2-3 minute interval post injection and was determined using the time–activity curve generated after the acquisition

Inhibitors,research,lifescience,medical was completed. Endpoints Endpoints analyzed included relative renal function on renal scintigraphy, biochemical endpoints, and dose volume parameters. Change in split renal function was evaluated by comparison of the relative contribution of each kidney on renogram. Biochemical endpoints used to assess change in renal function included Inhibitors,research,lifescience,medical serum creatinine and creatinine clearance. Creatinine clearance was calculated using the Cockcroft-Gault formula: (140-age)

x (weight in kilograms) / (72 x serum creatinine) (15). This value was adjusted for female gender by multiplying the creatinine clearance x 0.85. Renal scintigraphy, laboratory data, and biochemical endpoints were determined prior to and after radiation in 6 month intervals. Statistical analysis Statistical analyses for categorical variables were performed using Fisher’s Inhibitors,research,lifescience,medical exact test while continuous variables were analyzed using the Wilcoxon non-parametric test with exact p-values obtained using Monte-Carlo MK-2206 molecular weight estimates. Change in outcome variables over time were assessed using a repeated measures model. To account for missing data, a pattern mixture model all was used. Values for continuous variables are given as mean (standard deviation) while values for categorical data are specified as number (percentage). Statistical analysis was performed using SAS Statistical analysis software version 9.1.3 (SAS Institute Inc, Cary, NC, USA). A nominal significance level of 0.05 was used. Results Patient and treatment characteristics One hundred thirty six patients were identified who received abdominal radiation with concurrent chemotherapy, had renal scintigraphy performed prior to radiation, received at least 20 Gy, and had dose volume parameters and mean kidney doses available for analysis.