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Pretransplant CT estimated renal volume is not a predictor of graft function post transplantation

Introduction: There appears to be a critical nephron mass required to handle the metabolic demands of the body. The relationship between an individual's glomerular number and their weight is called the ‘nephron dose’. Inadequate nephron dose results in hyperfiltration and renal dysfunction. In healthy kidneys, there is a linear relationship between the renal weight and the glomerular number, but as it is impossible to measure the donor renal weight prior to excision, various surrogate measures have been reported. These include BMI, ultrasound and MRI volume studies. No studies assessing CT estimated renal volumes have previously been reported. Methods: In this retrospective cohort study, we analysed the data from 48 patients receiving live-donor renal transplants between June 2001 and November 2003 at our institution. The donor renal volume-recipient weight (Vol/Wt) ratio was calculated for each patient and compared to the GRF at 1, 3 and 6 months posttransplantation. Vol/Wt ratio to GFR was analysed as continuous, categorical and tertile variables. Results: There was no relationship found between Vol/Wt ratio and GFR at 1, 3 or 6 months posttransplantation. Conclusion: Using CT renal volume estimations as a surrogate for nephron number does not allow one to predict short term renal function after living donor transplantation.