Baseline living-donor kidney volume and function associate with 1-year post-nephrectomy kidney function.

Living donors may develop kidney dysfunction more often than equally healthy populations. The purpose of this study was to determine whether computed tomography-assessed remaining kidney volume indexed to body surface area (RKV/BSA) was associated with 1-year post-nephrectomy renal function independent of baseline renal function. Using multivariable regression, we modeled 1-year estimated glomerular filtration rate (eGFR) and eGFR <60 mL /min/1.73 m2 and considered pre-determined baseline eGFR subgroups in 151 consecutive donors. Mean ± SD baseline age, eGFR, RKV, BSA, and RKV/BSA were 38 ± 11 years, 97 ± 16 mL/min/1.73 m2 , 153 ± 29 mL, 1.9 ± 0.2 m2 , and 80.0 ± 12.8 ml/m2 , respectively; 50% were female and 94% were white. Mean baseline eGFR was greater with increasing RKV/BSA tertiles (92 ± 14, 97 ± 16, 107 ± 16 mL/min/1.73 m2 ; P < 0.001). Post-nephrectomy eGFR remained separated by RKV/BSA tertiles. At baseline, each SD greater RKV/BSA and eGFR was independently associated with higher adjusted 1-year eGFR by 2.4 and 9.2 mL/min/1.73 m2 . Each SD greater age associated with 2.2 mL/min/1.73 m2 lower adjusted 1-year eGFR. Adjusted odds of 1-year eGFR <60 increased significantly for donors with RKV/BSA <80 mL/m2 . With baseline eGFR <90, probability of 1-year eGFR <60 increased to >80% with decreasing RKV/BSA values below 80 mL/m2 . Those with baseline eGFR >100 rarely developed 1-year eGFR <60 if RKV/BSA remained >60 mL/m2 . RKV/BSA independently associated with 1-year eGFR <60, especially with lower baseline eGFRs. Additional studies should evaluate the predictive utility of this measure and its potential role in donor evaluations and informed consent.

Effect of donor kidney volume on recipient outcome: does the "dose" matter?

BACKGROUND: The effect of donor kidney volume on recipient kidney function has not been fully evaluated. METHODS: We performed a prospective analysis of 125 consecutive living kidney donor/recipient pairs. Donor kidney volume was calculated from pretransplantation computed tomography angiograms using a three-dimensional computerized volume method. Cortical volume was calculated from arterial phase and total volume from delayed phase. Because weight is a surrogate marker for metabolic demands, we looked at the "volume dose" by calculating the ratio of donor kidney volume to recipient weight. Recipient kidney function was assessed by calculating the estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration formula. Logistic regression models were used to evaluate odds of developing eGFR of <60 mL/min per 1.73m(2) (eGFR<60) at 12 months. RESULTS: Because cortical and total volumes were correlated (R=0.734, P<0.001), we used total kidney volume to evaluate the dose effect. The mean donated volume dose (SD) was 2.13 (0.62) mL/kg. The mean recipient eGFR at 12 months was 63.6 (17.3) mL/min per 1.73 m, and it correlated with volume dose (r=0.341, P<0.001). Compared with the lowest tertile, those in the highest tertile of donor kidney volume to recipient weight had lower odds ratio of developing eGFR of less than 60 mL/min per 1.73 m(2) (odds ratio, 0.23; 95% confidence interval, 0.07-0.81) in a multivariate logistic regression model. Spline regression suggested that a volume dose greater than 2.5 mL/kg was associated with lowest risk of eGFR of less than 60 mL/min per 1.73 m(2) at 12 months. CONCLUSIONS: Donor kidney volume dosing is an important determinant of recipient graft outcomes and may predict recipient kidney function in kidney transplantation.