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Kidney Week

Abstract: FR-OR038

Impact of Kidney Transplantation on Bone Microarchitecture: A Longitudinal Study

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Meng, Catarina, University Hospitals Leuven, Leuven, Belgium
  • Behets, Geert J., University of Antwerp, Antwerp (Wilrijk), Belgium
  • D'Haese, Patrick C., University Antwerp, Edegem, Belgium
  • De loor, Henriette, University Hospitals Leuven, Leuven, Belgium
  • Evenepoel, Pieter, University Hospitals Leuven, Leuven, Belgium
Background

Patients with chronic kidney disease (CKD) who undergo kidney transplantation experience increased risk of fracture. Bone microarchitecture is a major contributor to overall bone strength. High bone remodeling has been reported to be associated with cortical bone loss in CKD. The present prospective observational study aimed to investigate the impact of kidney transplantation on cortical and trabecular microarchitecture.

Methods

Bone biopsies were performed in 49 patients (56 yrs, males 69%) at the time of transplantation, with paired samples available in 30 patients 1 year after transplantation. Structural parameters were analysed by histomorphometry (trabecular bone only) and micro-CT including trabecular bone volume, thickness (TbTh), separation (TbSp) and cortical thickness (CtTh) and porosity (CtPo). Cortical region of interest was independently defined in baseline and follow-up scans. Parameters of mineral metabolism (including PTH, sclerostin, FGF23) and bone turnover markers (BTMs, including trimeric N-terminal propeptide [P1NP] and tartrate-resistant acid phosphatase 5b [TRAP5B]) were monitored as well.

Results

Changes of parameters of mineral metabolism were as expected (e.g. 1-84 PTH 320 vs 85 ng/ml, median, pre vs post) and bone turnover markers showed a significant decrease after transplantation (e.g. P1NP 109 vs 60 µg/L; TRAP5B 6.2 vs 3.9 U/L, median). Parameters of microarchitecture, overall remained stable, with only TbTh (as assessed by µCT) showing a modest but significant decline. Parameters of mineral metabolism and BTMs failed to correlate with parameters of microarchitecture. µCT and histomorphometry derived parameters of microarchitecture showed moderate correlation (r between 0.4 and 0.6).

Conclusion

Contemporaneous kidney transplantation has no or minimal impact on bone microarchitecture, noteworthy on cortical indices. This beneficial outcome may be a reflection of (adequate) suppression of bone remodeling following transplantation.

 parameterBaselineYear 1p-value
HistomorphometryBAr/TAr (%)18.0 (13.4-24.2)18.9 (14.5-23.7)1.0
TbTh (µm)134.9 (113.1-148.6)124.1 (110.9-140.5)0.7
TbSp (µm)409.0 (303.5-504.1)383.7 (313.7-949.6)0.2
µCTBV/TV (%)16.2 (13.5-21.6)14.5 (11.5-17.8)0.02
TbTh (µm)134.7 (118.2-151.9)125.3 (115.2-129.4)0.03
TbSp (µm)677.8 (557.0-754.5)653.6 (596.3-763.2)0.9
CtPo (%)10.2 (8.0-16.3)9.5 (7.3-14.6)0.2
CtTh (mm)0.676 (0.548-0.853)0.610 (0.507-0.941)0.5