Factors that Influence Graft Function at 1-Year Posttransplantation and Correlation with Baseline Donated Kidney Function Measured with Radioisotopes

Abstract

Abstract Introduction. Assessment of renal function is a crucial component of donor evaluation. The higher measured donor GFR is independently associated with a better allograft outcomes in living donor kidney transplantation (LDKT). Monitoring graft function and estimation of GFR is a recommended method for patients’ follow-up in posttransplantation period. The aim of our study was to investigate the correlation of directly measured GFR of donated kidney with estimated GFR through creatininebased formulas and to detect impact factors on the graft function at 12 months posttransplantation. Methods. Fifty LDKT patients (related and nonrelated donors) with stable renal function in a period of 12 months after transplantation were included in our study. The mean recipient age was 30.7±9.6 years, and donor age 55.45±9.41 years. The mean directly measured donated kidney GFR was 47.61±5.72 ml/min. Graft function was estimated at 3, 6 and 12 months by 3 formulas: Cockcroft- Gault (C-G), MDRD 6 variables and Nankivell. Direct correlation of estimated with measured radiolabeled 99mTc DTPA GFR was performed. Various impact factors such as donor age, dialysis vintage and different calcineurin inhibitors as a part of immunosupression were evaluated. Results. Estimated GFR at 12 months with MDRD, Cockroft Gault, and Nankivell formulas was 72.65±22.6, 94.25±36.42, and 81.78±17.89 ml/min, respectively. The highest estimated GFR was obtained with C-G formula at all three time points. The estimated allograft GFR did not correlate with directly measured GFR of donated kidney. Donor age well correlated with the graft function at 12 months. Allografts from standard criteria donors-SCD (<60 years) had better function than allografts form expanded criteria donors-ECD (>60 years). The highest GFR was estimated with C-G equation (106.08±39.26 ml/min), while GFR estimated with Nankivell was 86.86±15.30 ml/min, and with MDRD 79.67±20.28 ml/min, presenting patients in stage 2 of chronic kidney disease. Duration of hemodialysis treatment under 24 months showed better graft function estimated by C-G at 12 months (102.23±38.86 ml/min), compared to that above 24 months of HD (77.84±18.11 ml/ min). Different type of calcineurin inhibitors did not influence on the graft function at any time point. Conclusion. Creatinine-based formulas for estimation of the graft function did not correlate with directly measured function of the donated kidney with radiolabeled isotopes, nor between each other. Hence, the monitoring of the graft function should be done by a single formula in the posttransplantation period. Expectedly, a better graft function was observed in young donors (standard criteria) and in patients with shorter hemodialysis treatment.