Evaluation of Renal Functional Reserve in Adult Living Kidney Donors

Background: Renal functional reserve (RFR) assessed by renal response to a protein load is considered to reflect functional reserve capacity and is believed to be a tool for screening living donors Methods: A descriptive, observational and prospective study was carried out in a single center where 22 living kidney donors, over 18 years of age, clinically healthy, were considered between the month of July 2023 to May 2024. RFR was measured with a test of the glomerular stress using an oral protein loading test Results: Of a total of 22 patients included, the median age was 39 (18-56) years, 77% (17) women. Body mass index was 25.5 (20.2 to 32.7). Median baseline Cr was 0.67 (0.47-1.04) mg/dl, median baseline cystatin was 0.67 (0.40-0.9) mg/dl versus post-cystatin. stress was 0.6 (0.30-0.90) mg/dl. The median values of bGFR and sGFR were statistically different (123.54 [56.38 -250.11] vs. 178.71 [84.88 - 418.43] ml/min/1.73 m2, p = 0. 0017. A difference will be observed between bGFR and sGFR, with an RFR = 45.9% (11.87-132.62) equivalent to an increase in GFR after a protein load of 48.81 ml/min (16.24- 161.56) having a bGFR > 90 ml/min was associated with a risk of presenting borderline FRR < 30). ml/min OR 1.2 95% CI (1.0- 1.05) and a BMI < 30 estimated an OR 0.76 95% CI (0.60-0.96) protective factor to preserve an RFR > 30ml /min. Conclusion: The results suggest that glomerular renal stress testing by oral protein loading could be useful before transplantation to establish the original global filtration capacity of the donor kidneys. The results provide a previous global renal function of 48 ml/min, a result similar to that reported in the literature, drawing attention to the tendency in obese patients to present a low RFR, as well as the no association in the level of basal normality. creatines and RFR that may represent an inadequate estimate and present the patient's susceptibility to developing kidney injury before it becomes clinically evident