Purpose: Klotho is a protein produced in renal tubular cells with nephroprotective actions which acts as a co-receptor for phosphaturic factor FGF-23. The natural history of the production and expression of post-transplant klotho and FGF-23 is still unknown. Our aim is to know the evolution of these molecules during two years after kidney transplant (KT).

Methods: Klotho and FGF-23 levels were determined in 42 patients at baseline, third, twelve and twenty-fourth month after kidney transplant (KT), measured by ELISA. The glomerular filtration rate (GFR) of the kidney graft was performed by indirect methods (formula:MDRa and CKD-EPI) at each study visit.

Results: A total of 146 kidney transplant patients were included in the study and 42 patients have completed the follow-up. The clinical and demographic characteristics of donor and recipients are shown in Table 1. Klotho levels at the third month decreased significantly in both groups (basal 452,69±236,85 vs third month 408,83± 223,34;p=0.01) rising in month 12 (523.9±279.6), remaining at these values in the second year after KT (511.1±308.3), even higher than before KT. Similarly, when we analyzed the pre-transplant FGF23 in 56 patients, we observed a reduction trend at the third month, which was maintained until 24 months (baseline 783 vs 193.88 at third month, 158.32 at month 12 and 192.10 in month 24;p=0.066).

Conclusions: We describe a decreasement in Klotho levels which increase after one year post KT, which could be justified by the “stunned” of the renal tubule after KT, caused by ischemia-reperfusion time, tubular necrosis, treatment with calcineurin inhibitors, which improves and rises to levels even higher than those prior to KT. More prospective studies are needed to confirm these hypotheses.