Abstract
Background and Aims
Renal function decreases with aging. Aging is associated with significant changes in structure and function of the kidney. On the macrostructural level, kidney cortical volume decreases, therefore total kidney volume (TKV) also decreases with aging. On the microstructural level, the number of glomerulosclerosis increases, therefore nephron number decreases with aging. Some reports show that the decline of TKV and nephron number is accompanied by a reduction in renal function.
However, in the field of living kidney transplantation, TKV and glomerulosclerosis are not fully evaluated as factors influencing the donor’s post-transplant renal function.
Living kidney transplantation is an established renal replacement therapy for end-stage renal disease patients. To predict living kidney recipient’s renal function, one-hour protocol biopsy is conducted during the operation. From one-hour protocol biopsy, donor’s pathophysiological findings such as glomerulosclerosis can be evaluated. In this study, we evaluated the correlation of potential influencing factors including TKV and glomerulosclerosis with pre- and post-transplant renal function in living kidney donors.
Method
This is a retrospective study including all 37 living related kidney donors seen at Kyoto University Hospital from January 2013 to April 2019. Estimated glomerular filtration rate (eGFR) was calculated using equation for Japanese population from serum creatinine levels at pre- and post-transplant. TKV was calculated from the 3D volume-rendered images of enhanced CT (=π/6×length×width×thickness), and adjusted to standard body surface area (BSA) by individual BSA. The ratio of number of non-glomerulosclerosis per that of whole glomeruli (non-GS) was evaluated by protocol renal biopsy at one hour after renal reperfusion. This study protocol was approved by the Ethics Committee on human research of the Graduate School of Medicine, Kyoto University.
Results
We evaluated 37 living kidney donors (35.1% male, mean age 58.2 ± 12.0 years). Mean pre-transplant eGFR was 75.7 ± 12.1 ml/min/1.73m2, mean post-transplant eGFR; 44.9 ± 7.75 ml/min/1.73m2, adjusted TKV (aTKV); 349.3 ± 58.4 ml, and non-GS; 0.892 ± 0.086. Pre-transplant eGFR was associated with aTKV and aTKV×nonGS (r=0.525, 0.569 respectively, p<0.01). Post-transplant eGFR was associated with age (≧65 years old, p<0.01), aTKV, non-GS, and aTKV×non-GS (r=0.527, 0.344, 0.626 respectively, p<0.05). The rate of eGFR decline was associated with age (≧65 years old, p=0.044), but not with aTKV and non-GS, aTKV×non-GS.
Conclusion
These results suggest that non-GS and age are correlated with post-transplant renal function but not pre-transplant renal function in living kidney donor, and the decline rate of eGFR are correlated with age.
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