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Abstract: TH-PO590

Infilling of Individual Cortical Pores in the Setting of CKD

Session Information

Category: Bone and Mineral Metabolism

  • 401 Bone and Mineral Metabolism: Basic

Authors

  • Swallow, Elizabeth A., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Metzger, Corinne E., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Hammond, Max A., Indiana University - Purdue University Indianapolis, Cincinnati, Ohio, United States
  • Nickolas, Tom, Columbia University Medical Center, New York, New York, United States
  • Moe, Sharon M., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Allen, Matthew R., Indiana University School of Medicine, Indianapolis, Indiana, United States
Background

Cortical porosity is the most prominent skeletal phenotype in the setting of chronic kidney disease (CKD), and likely contributes to the increased fracture risk in CKD. Reducing cortical porosity is likely to confer improved bone mechanical properties yet data on this topic are limited. Although strategies aimed at prevention of cortical porosity development would be ideal, a more likely clinical scenario would require that existing cortical porosity be reduced through pore infilling. The purpose of this work was to test the hypothesis that cortical porosity can be reversed indicating porosity infilling.

Methods

Skeletally mature male rats (n=6) with established CKD (BUN > 2x normal age-matched animals and PTH values of ~500-2500 pg/mL) were scanned with high resolution CT before and after 5 weeks of 3% calcium drinking water to suppress PTH.

Results

Baseline imaging showed cortical porosity of the distal tibia ranging from 0.5% to 10.1% across the six animals. After 5 weeks of treatment PTH values ranged from ~30-80 pg/mL, BUN was unchanged, and cortical porosity was < 1% in all animals. Using a newly developed MATLAB program that allows tracking of individual pores, the overwhelming majority of pores (93%) completely filled in over the 5 week period while 6% of pores became smaller and only 2% of pores newly developed. Preliminary analysis on kidney transplant patients (n=2), using high-resolution peripheral CT scans of the distal tibia, show that that over 60% of the pores either completely infill or get smaller one year following kidney transplant. This was offset by newly formed pores or pores that got larger over the year, resulting in overall porosity being unchanged.

Conclusion

These data confirm that in the setting of CKD, cortical pores can fill in and that analysis methods that tracking individual pores over time provides a unique view of the dynamic changes to cortical bone porosity.