Abstract: FR-OR075

Acute and Mid-Term Mineral Disturbances Following Kidney Donation

Session Information

Category: Mineral Disease

  • 1201 Mineral Disease: Ca/Mg/PO4

Authors

  • Lim, Kenneth, Massachusetts General Hospital, Harvard Medical School, Boston, United States
  • Smith, Jane Clair, University of Cambridge, Cambridge, United Kingdom
  • McEniery, Carmel M., University of Cambridge, Cambridge, United Kingdom
  • Tomlinson, Laurie A., London School of Hygiene and Tropical Medicine, London, United Kingdom
  • Wilkinson, Ian, University of Cambridge, Cambridge, United Kingdom
  • Hiemstra, Thomas F., University of Cambridge, Cambridge, United Kingdom
Background

Unilateral nephrectomy performed for live transplant donation is increasing due to a greater demand for available organs. To counteract the growing transplant waiting list, the opportunity to donate organs has been extended to a broader population. However, these expanded criteria donors (ECDs) maybe at greater risk from a fall in GFR following unilateral nephrectomy. While emerging studies have demonstrated profound mineral disturbances that occur following kidney donation, whether acute disturbances in mineral homeostasis occur following unilateral nephrectomy is currently unknown.

Methods

We conducted the KARMA (Effect of Kidney Donation on Bone and Mineral Metabolism) study, a prospective controlled observational cohort study. Biochemical parameters were determined before and acutely after kidney donation on days 1-3 with mid-term follow-up at 6 weeks and 12 months in the donor group and at baseline, 6 weeks and 12 months in the control group.

Results

We enrolled 34 donors (59% male) and 34 healthy controls (47% male). Both groups had similar characteristics: mean (±SD) age (53±10 vs 50±14 years, p=0.33), BMI (26±2.8 vs 25.9±3.7, p=0.59), systolic BP (128±13 vs 130±6, p=0.59), diastolic BP (80±9 vs 81±9, p=0.68) and baseline GFR (84.4±20.2 vs 83.6±25.2 ml/min/1.73m2, p=0.89). Kidney donation reduced eGFR significantly from 84.4±20.2 to 52.3±17.5 (p<0.001) acutely by day 1 and remained lower than baseline by 6 weeks (60.0±20.0; p<0.001) and 12 months (88.6±24.3; p<0.001). Phosphate levels increased from baseline by day 1 (1.1[0.9,1.2] to 1.3[1.1, 1.4], p <0.001) and then declined to 0.8[0.8, 1.0] by day 2 (p<0.001) before normalizing by 6 weeks. Albumin-corrected calcium declined on day 1 (p=0.003) but did not differ at 6 weeks or 12 months after donation. PTH levels did not rise significantly from baseline until 1 year (4.77[3.39, 5.8] vs 5.8[4.56, 8.7]; p=0.018). FGF-23 levels were statistically unchanged at all time points. However, soluble α-Klotho levels were significantly reduced by day 1 (p=0.001) and remained low at 6 weeks (p=0.02) and 1 year (p=0.04).

Conclusion

Profound mineral disturbances occur acutely after kidney donation. Acute mineral disturbances in phosphate and calcium occur independently of changes in the phosphaturic hormones, PTH and FGF-23. Serum α-Klotho levels decline acutely following unilateral nephrectomy.

Funding

  • Private Foundation Support