Evaluation of Risk Factors for Kidney Function Decline and Chronic Kidney Disease in Living Kidney Donors

<b>Background/Objectives</b>: Living kidney donors (LKDs) can be at risk of chronic kidney disease (CKD). Several conditions are associated with hyperfiltration, such as solitary kidney, obesity, and high protein consumption. In this regard, we aimed to evaluate the risk factors for kidney function decline in LKDs and the effect of daily protein intake. Methods: Data collected from 220 living kidney donors (mean age: 48.35 ± 12.4 years; 55% female) between 2016 and 2023 were evaluated. One-year and long-term outcomes were evaluated following donor nephrectomy, along with the risk factors for GFR decline and the development of CKD. <b>Results</b>: The percentage of eGFR decline was 31.15 (IQR: 19.81-37.5) in the first year and 28.18 (IQR: 18.75-38.16) in the third year after donation. None of the donors had end-stage renal disease during the 31 (IQR: 19-71) months. CKD developed in 31 (23.1%) LKDs. In the first year, the risk factors associated with a decline in eGFR exceeding 30% included male gender (OR: 0.25; 95% CI: 0.11-0.57; <i>p</i>: 0.001) and baseline eGFR value (OR: 0.95; 95% CI: 0.92-0.98; <i>p</i>: 0.002). At the final visit, the risk factors were male gender (OR: 7.19; 95% CI: 3.06-16.94; <i>p</i> < 0.001), age (OR: 1.06; 95% CI: 1.02-1.10; <i>p</i>: 0.001), and BMI (OR: 1.12; 95% CI: 1.01-1.23; <i>p</i>: 0.030). For the development of CKD, the risk factors were male gender (OR: 0.25; 95% CI: 0.09-0.71; <i>p</i>: 0.009) and baseline eGFR (OR: 0.88; 95% CI: 0.83-0.93; <i>p</i> < 0.001). No association was observed between daily protein intake and renal outcomes in LKDs following donor nephrectomy. <b>Conclusions</b>: In the present study, there was no significant unexpected decline in kidney function in donors in the short-term and the medium-term. Age, BMI, and low basal eGFR values should be carefully considered for LKD evaluation. Furthermore, our findings indicated that protein intake does not substantially impact the GFR. Further controlled studies are required to support our findings.