Ontology highlight
ABSTRACT: Context
The physiologic role of free 25-hydroxyvitamin D [25(OH)D] in humans is unclear.Objective
To assess whether rise in total vs free 25(OH)D is associated with change in downstream biomarkers of 25(OH)D entry into target cells in kidney and parathyroid: 24,25-dihyroxyvitamin D [24,25(OH)2D] and PTH, respectively.Design
16-week randomized controlled trial.Intervention
60 μg (2400 IU)/d of D3 or 20 μg/d of 25(OH)D3.Setting
Academic medical center.Participants
35 adults age ≥18 years with 25(OH)D levels < 20 ng/mL.Main outcome measures
24,25(OH)2D, 1,25-dihyroxyvitamin D [1,25(OH)2D] and PTH.Results
At baseline, participants [D3 and 25(OH)D3 groups combined] were 35.1 ± 10.6 years. Mean total 25(OH)D, free 25(OH)D, 24,25(OH)2D, and PTH were 16.6 ng/mL, 4.6 pg/mL, 1.3 ng/mL, and 37.2 pg/mL, respectively. From 0 to 4 weeks, rise in only free 25(OH)D was associated with a concurrent 24,25(OH)2D increase [P = 0.03, adjusted for change in 1,25(OH)2D and supplementation regimen] and PTH decrease (P = 0.01, adjusted for change in calcium and supplementation regimen). Between 4 and 8 weeks, and again from 8 to 16 weeks, rises in free and total 25(OH)D were associated with 24,25(OH)2D increase; in contrast, rise in neither total nor free 25(OH)D was associated with PTH decrease during these time periods.Conclusions
Early rise in free 25(OH)D during treatment of vitamin D deficiency was more strongly associated with changes in biomarkers of 25(OH)D entry into target kidney and parathyroid cells, suggesting a physiologic role of free 25(OH)D in humans.
SUBMITTER: Shieh A
PROVIDER: S-EPMC6126886 | biostudies-literature | 2018 Sep
REPOSITORIES: biostudies-literature
Shieh Albert A Ma Christina C Chun Rene F RF Wittwer-Schegg Jonas J Swinkels Leon L Huijs Tonnie T Wang Jeffrey J Donangelo Ines I Hewison Martin M Adams John S JS
The Journal of clinical endocrinology and metabolism 20180901 9
<h4>Context</h4>The physiologic role of free 25-hydroxyvitamin D [25(OH)D] in humans is unclear.<h4>Objective</h4>To assess whether rise in total vs free 25(OH)D is associated with change in downstream biomarkers of 25(OH)D entry into target cells in kidney and parathyroid: 24,25-dihyroxyvitamin D [24,25(OH)2D] and PTH, respectively.<h4>Design</h4>16-week randomized controlled trial.<h4>Intervention</h4>60 μg (2400 IU)/d of D3 or 20 μg/d of 25(OH)D3.<h4>Setting</h4>Academic medical center.<h4>Pa ...[more]