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Introduction

Computer Tomography based volume measurements (CT Volumetry) in living kidney donor imaging have been shown to correlate well with nuclear based split renal function, potentially facilitating more thoughtful selection of the side for donor nephrectomy. However, the impact of removing the relatively larger volume kidney on post donor nephrectomy renal function has not been widely studied. We compared the 6 month post-donation renal function of patients who gave their larger kidneys (on CT scan), with that of patients who did otherwise. _x000D_

Methods

A clinical chart review of 103 consecutive patients (Mean Age 45.28 ±12.7, Males, n=49) who underwent uncomplicated donor nephrectomy from 2010 to 2015 was performed. All patients' bilateral kidney volumes were measured based on their preoperative CT scans. Estimated glomerular filtration rate (eGFR) was determined using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation - before and 6 months after surgery. Patients were divided into two groups and compared. Group 1 (n=29) consisted of patients who underwent donor nephrectomy of the side larger than the remaining side by 5% or more of the total kidney volume.

Results

Patients in Group 1 and 2 (n=74) were not significantly different (P=NS) respectively in terms of age (43.9 vs. 46.4), BMI (22.9 vs. 25.3) gender and racial distribution (58.6 vs. 51.4% Female and 59 vs. 59% Chinese). Both patient groups had equivalent proportion of controlled hypertension and hyperlipidaemia. Surgical approach, arterial number and side were not significantly different. Although total kidney volumes were equivalent between group 1 and 2 (264.8±65.4 vs. 283.6±55.9mls, P=NS), Group 1 had significantly smaller right kidney volumes (111.2±24.7 vs. 142.2±27.3mls, P=0.04). Of note, the kidney removed in 2 of 29 patients in Group 1 was 10% greater by split renal function in terms of volume than the remaining side. EGFR pre-operatively (113.6±20.0 vs.105.8.0±22.4mL/min/1.73m 2 ) and at 6 months (66.3±13.2 vs. 65.9±15.6mL/min/1.73m 2 ) were not significantly different between the two groups. Despite this, patients in group 1 had a significantly greater absolute (53.9±3.3 vs. 42.0±14.6 mL/min/1.73m 2 ,) P=0.01)and relative decline (44.7% vs. 37.1% P=0.01)in eGFR at 6 months compared to group 2.

Conclusions

At a threshold split renal function difference by kidney volume of 5% between the 2 sides, removal of the larger kidney for living kidney donation will result in a significantly greater early decline in an individual's renal function than kidney donors whose larger or equivalent kidney is preserved.

Funding

None