title: The vitamin D metabolite ratio (VMR) as a predictor of functional biomarkers of bone health.
abstract: BACKGROUND
  The vitamin D metabolite ratio (VMR) (serum 24,25(OH)2D3/25(OH)D3) has been proposed as a biomarker of vitamin D sufficiency to replace serum 25(OH)D.
  
  
  OBJECTIVE
  To examine the relationships of 24,25(OH)2D3and VMR to functional biomarkers of bone health following vitamin D supplementation.
  
  
  METHODS
  An ambulatory research centre.
  
  
  METHODS
  Serum from a previous research study of dose response of PTH, calcium absorption and bone turnover to vitamin D supplementation was analysed for vitamin D metabolites (25(OH)D, 24,25(OH)2D3).
  
  
  RESULTS
  The relationship of serum 24,25(OH)2D3and VMR to calcium absorption, PTH and bone turnover markers was examined.
  
  
  RESULTS
  Although there were strong correlations of serum 25(OH)D with 24,25(OH)2D3and free 25(OH)D, its correlation with VMR was lower. After vitamin D supplementation, the change in 25(OH)D, 24,25(OH)2D3and VMR was associated with the change in calcium absorption, PTH and CTX. The correlation of the change in PTH with the change in metabolites was the lowest for VMR. Moreover, estimated dose response for standardized values of vitamin D metabolites showed a beta-coefficient for VMR that was significantly less in magnitude compared to other metabolites.
  
  
  CONCLUSIONS
  Serum 24,25(OH)2D3is closely associated with the dose response of serum 25(OH)D to vitamin D supplementation. However, the VMR does not appear to be equivalent to either of these metabolites in its response to increasing vitamin D intake or its association with PTH. It is unlikely that VMR will replace 25(OH)D as a biomarker for vitamin D sufficiency.
authors.affiliation: Bone Mineral Research Center, Winthrop University Hospital, Mineola, NY, USA.
authors.forename: John
authors.identifier: http://orcid.org/0000-0002-4130-7717
authors.initials: J
authors.lastname: Aloia
authors.affiliation: Bone Mineral Research Center, Winthrop University Hospital, Mineola, NY, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Fazzari
authors.affiliation: Bone Mineral Research Center, Winthrop University Hospital, Mineola, NY, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Shieh
authors.affiliation: Bone Mineral Research Center, Winthrop University Hospital, Mineola, NY, USA.
authors.forename: Ruban
authors.initials: R
authors.lastname: Dhaliwal
authors.affiliation: Bone Mineral Research Center, Winthrop University Hospital, Mineola, NY, USA.
authors.forename: Mageda
authors.initials: M
authors.lastname: Mikhail
authors.affiliation: University of Washington, Seattle, WA, USA.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Hoofnagle
authors.affiliation: Bone Mineral Research Center, Winthrop University Hospital, Mineola, NY, USA.
authors.forename: Lou
authors.initials: L
authors.lastname: Ragolia
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3 / Q000097:blood*; D000368:Aged; D015415:Biomarkers / Q000097:blood; D016723:Bone Remodeling / Q000502:physiology*; D002112:Calcifediol / Q000097:blood*; D002118:Calcium / Q000378:metabolism*; D024042:Collagen Type I / Q000097:blood; D006801:Humans; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D010455:Peptides / Q000097:blood; D014807:Vitamin D / Q000008:administration & dosage / Q000494:pharmacology*; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D014807:Vitamin D; D015650:24,25-Dihydroxyvitamin D 3; D002112:Calcifediol; D002118:Calcium