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Kidney Week

Abstract: FR-PO315

Evaluation of Mineral and Bone Metabolism in Living Kidney Donors: A 10-Year Follow-Up

Session Information

Category: Bone and Mineral Metabolism

  • 502 Bone and Mineral Metabolism: Clinical

Authors

  • Duque, Eduardo Jorge, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Ferreira, Gustavo, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Oliveira, Ivone Braga de, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Dominguez, Wagner, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Agena, Fabiana, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Jorgetti, Vanda, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Lemos, Francine, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Wolf, Myles, Duke University, Durham, North Carolina, United States
  • David-Neto, Elias, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Moyses, Rosa M.A., Universidade de Sao Paulo, Sao Paulo, Brazil
Background

Living kidney donors (LKD) experience an abrupt decline in glomerular filtration rate (GFR) resulting in abnormalities of mineral and bone metabolism (MBD), and this may have implications for the skeletal health. We prospectively studied acute and long term MBD adaptation of LKD from two kidney transplant centers (Brazil and USA).

Methods

We have measured renal function and MBD parameters longitudinally after live kidney donation (KD, baseline – D0, day 1, 14, 180 and 360 post-operatively) in 74 live donors (40ys, 73% female, 54% Brazilian). A subset of 20 brazilian LKD were reassessed after 10 years of KD.

Results

At baseline, Brazilian LKD presented lower FGF23 (20.8 vs 80.1 pg/mL*) and higher PTH (47.4 vs 40.1*) than their US counterparts. GFR decreased 41% just after KD, but improved 11% during the first year. PTH increased on D1 (65±30 vs D0 44±14 pg/mL*), as well as FGF23, which remained significantly higher at D360 (60 vs D0 44.4 pg/mL*). There was a reduction in serum phosphate (3.3±0.6 vs D0 3.7±0.5 mg/dL*) and calcium (7.9±0.5 vs D0 9.4±0.4 mg/dL*) on D1, which returned to baseline levels at D180 (3.5±0.6 and 9.4±0.5mg/dL, respectively). A higher fractional excretion of phosphate (FEP) was noted since D14. After 10 years of KD, Brazilian LKD presented a significant reduction in GFR [65 (55-69)ml/min] and in FGF23 [21.7 (18-30)pg/mL], as well as an increase in PTH [57 (42-66)pg/mL] and calcium levels. Despite that, FEP reduced and phosphate levels remained stable (figure 1). *p<0.05

Conclusion

The abrupt decline in kidney mass is associated with an increase in PTH and FGF23, which could not be explained by phosphate retention. In a long term evaluation, LKD showed a sustained drop in GFR, accompanied by an increase in PTH and calcium levels, while the reduction in FGF23 and FEP maintained phosphate stable.