Abstract: SA-PO889

Relationships between Vitamin D and Bone Formation and Mineralization in Adults and Children with Pre-Dialysis CKD

Session Information

  • Mineral Disease: CKD-Bone
    November 04, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Mineral Disease

  • 1203 Mineral Disease: CKD-Bone

Authors

  • Nickolas, Thomas, Columbia University Medical Center, New York, New York, United States
  • Pereira, Renata C., University of California, Los Angeles, California, United States
  • Coco, Maria, Montefiore Medical Center , Bronx, New York, United States
  • Ix, Joachim H., UCSD, San Diego, California, United States
  • Chonchol, Michel, University of Colorado, Aurora, Colorado, United States
  • Pullman, James M., Montefiore Medical Center, Bronx, New York, United States
  • Sprague, Stuart M., NorthShore University HealthSystem University of Chicago Pritzker School of Medicine, Chicago, Illinois, United States
  • Salusky, Isidro B., Mattel Children's Hospital, Los Angeles, California, United States

Group or Team Name

  • Kidney Disease Bone Biopsy Working Group
Background

The Institute of Medicine (IOM) recommends levels of 25-hydroxyvitamin D (25D) >20ng/mL to optimize bone quality for the general population. In contrast, optimal 25D levels in adults and children with pre-dialysis CKD have not been established. We used bone-tissue level data to investigate the 25D level that is associated with optimal turnover and mineralization in adult and pediatric patients with pre-dialysis CKD.

Methods

From Columbia University, Montefiore Medical Center, NorthShore University and UCLA, we pooled iliac crest bone biopsies with tetracycline double labeling and quantified relationships between 25D and 1,25-dihydroxyvitamin D (1,25D) and histomorphometry in 25 adults and 31 children with CKD. Spearmen correlations were adjusted for kidney function (CKD-EPI in adults; Schwartz Formula in children). To determine 25D levels that optimized bone formation and mineralization we used receiver operator curve (ROC) analysis and defined high turnover renal osteodystrophy (ROD) as bone formation or mineralization in the upper tertile of respective adult and pediatric populations.

Results

In adults, mean±SD age and GFR were 63±14yrs and 27±18mL/min, respectively, and levels of 25D and 1,25D were 28±17ng/mL and 34±20pg/mL, respectively. 25D was inversely correlated with bone formation rate (BFR; r -0.47, p0.02) and mineralizing surface (r -0.48, p0.02), and 1,25D was inversely correlated with osteoid surface (r -0.54, p0.006). In ROC analysis, 25D levels ≥35ng/mL provided 100% specificity of both non-high turnover and normal mineralization rates and no patient had high turnover ROD. In contrast, >60% of patients with 25D <35ng/mL had high turnover ROD. In children, age and GFR were 14±4yrs and 50±21mL/min respectively and levels of 25D and 1,25D were 27±7ng/mL and 33±14pg/mL, respectively. 25D did not correlate with histomorphometry, but 1,25D was positively correlated with BFR (r 0.41, p0.02) and mineral apposition rate (r 0.46, p0.01).

Conclusion

Relationships between 25D and 1,25D and bone differ in adult and pediatric CKD patients. In adults, 25D levels that are greater than the IOM recommendations may be needed to optimize bone quality. In children, 1,25D may have more of an effect on bone quality than 25D. Larger studies will further explore these findings.

Funding

  • NIDDK Support