Does size really matter? A retrospective analysis of donor renal volume and its effects on renal function in donors after donation

Introduction: It has been postulated that renal volume should play a bigger role in selection of donor kidney apart from anatomy and that the larger kidney should be kept for the donor. We attempted to investigate the correlation between donor residual renal volume and post-transplant donor renal function up to 5 years post donation. Material and methods: Retrospective analysis was performed on all living related renal transplant at a tertiary institution from 2005-2013. Pre-operative renal volumes of donors were calculated using computer tomography (CT) images. Serum creatinine and creatinine clearance levels were collected at pre-operative, 6 months, 1 year, and 5 years post donation. Percentage residual renal volume was correlated against the percentage change in serum creatinine and creatinine clearance over the specified time points. Results: Eighty-four donors were analyzed and the left kidney was removed in all patients. Median age was 46 years (22-76), median pre-operative renal volume was 261 cm 3 (142–453) and median percentage of residual renal volume was 44% (29-55). Median serum creatinine at pre-operative, 6 months, 1 year, and 5 years were 65, 96, 99, and 91 μmol/L respectively. Median creatinine clearance at pre-operative, 6 months, 1 year and 5 years were 113, 76, 74 and 81 ml/min respectively. Serum creatinine trend showed improvement up to 5 years but creatinine clearance stabilized after 6 months. When compared against percentage residual renal volume, there were no significant correlations found with percentage change in serum creatinine and creatinine clearance over pre-operative, 6 months, 1 year or 5 years. Discussion: There is no association between donated renal volume and changes in serum creatinine or creatinine clearance. Size of the donated kidney does not matter.