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Abstract: PO0340

The Vitamin D Metabolite Ratio and Change in Bone Density and Fracture Risk in Older Adults

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Ginsberg, Charles, University of California San Diego, La Jolla, California, United States
  • Katz, Ronit, University of Washington School of Medicine, Seattle, Washington, United States
  • Hoofnagle, Andrew N., University of Washington School of Medicine, Seattle, Washington, United States
  • Hughes-Austin, Jan M., University of California San Diego, La Jolla, California, United States
  • Miller, Lindsay M., University of California San Diego, La Jolla, California, United States
  • Becker, Jessica Osborn, University of Washington School of Medicine, Seattle, Washington, United States
  • Kritchevsky, Stephen B., Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
  • Shlipak, Michael, University of California San Francisco, San Francisco, California, United States
  • Sarnak, Mark J., Tufts Medical Center, Boston, Massachusetts, United States
  • Ix, Joachim H., University of California San Diego, La Jolla, California, United States
Background

Recent studies have suggested that 25-hydroxyvitamin D [25(OH)D] may be a poor biomarker of bone health. Higher concentrations of its catabolic product 24,25-dihydroxyvitmin D [24,25(OH)2D3] and a higher ratio of 24,25(OH)2D3 to 25(OH)D3 (the vitamin D metabolite ratio [VMR]) may provide additional information on vitamin D receptor activity and bone health.

Methods

We measured 24,25(OH)2D3, 25(OH)D3, 25(OH)2D3 and serial bone densitometry scans over a 9-year period, in 761 community dwelling older adults, that participated in the Health Aging and Body Composition Study. Participants were followed for a median time of 11 years for any fractures. 24,25(OH)2D3 and 25(OH)D3 were used to calculate the VMR. We used linear mixed models to assess the relationship between 24,25(OH)2D3, 25(OH)D3,1,25(OH)2D3 and the VMR with annual change in hip, lumbar and thoracic spine bone mineral density (BMD). We used Cox models to assess the relationships between these parameters and fracture risk.

Results

Study participants had mean age 75+/- 3 years, 49% were female, 42% were black, and 23% had CKD. In fully adjusted models, a doubling of VMR and 24,25(OH)2D3 were associated with an 0.6% (95% CI 0.3, 0.9%) and an 0.3% (95% CI 0.1, 0.3%) increase in annual change in hip BMD, respectively (Table 1). We found similar relationships with thoracic and lumbar spine BMD. 25(OH)D3 and 1,25(OH)2D3 concentrations were not associated with any of the BMD measurements. There were 194 fractures in follow-up. A higher VMR was associated with a lower risk of fracture [HR 0.71 (95% CI 0.51, 0.97) per doubling of VMR, Table 1]. Associations of 24,25(OH)2D3, 25(OH)D3,1,25(OH)2D3 with fracture risk did not reach statistical significance.

Conclusion

In diverse cohort of community dwelling older adults, a higher VMR was associated with improvement in BMD and a lower risk of fracture. Trials are needed to evaluate the VMR as a therapeutic target in persons at risk for worsening BMD and fracture.

Funding

  • NIDDK Support