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Published on: May 4, 2018
Racial differences in calculated bioavailable vitamin D with vitamin D/calcium supplementation
Michael T Yin1, Ellen S Chan, Todd T Brown
1aColumbia University Medical Center, New York City, New York bHarvard T.H. Chan School of Public Health, Boston, Massachusetts cJohns Hopkins University School of Medicine, Baltimore, Maryland dHospital of the University of Pennsylvania, Philadelphia, Pennsylvania eCase Western Reserve University, Cleveland, Ohio fGilead Sciences, Foster City, California gBristol-Myers Squibb, Plainsboro, Middlesex County, New Jersey hDuke University Community Advisory Board, Durham, North Carolina iUniversity of Alabama, Birmingham, Alabama, USA.
Objectives:
Some studies suggest that bioavailable 25-dihydroxyvitamin D [25-(OH)D] is more accurate than total 25-(OH)D as an assessment of vitamin D (VitD) status in black individuals. We hypothesized that increases in bioavailable 25-(OH)D would correlate better with improvement in bone outcomes among black HIV-infected adults.
Design:
This is a secondary analysis of AIDS Clinical Trials Group A5280, a randomized, double-blind study of VitD3 and calcium supplementation in HIV-infected participants initiating antiretroviral therapy.
Methods:
Effect of VitD/calcium on total and calculated bioavailable 25-(OH)D, parathyroid hormone, bone turnover markers, and bone mineral density in black and nonblack participants were evaluated at 48 weeks. Wilcoxon signed-rank tests and Wilcoxon rank sum tests assessed within and between-race differences.
Results:
Of 165 participants enrolled, 129 (40 black and 89 nonblack) had complete data. At baseline, black participants had lower total 25-(OH)D [median (Q1,Q3) 22.6 (15.8, 26.9) vs. 31.1 (23.1, 38.8) ng/ml, P < 0.001] but higher bioavailable 25-(OH)D [2.9 (1.5, 5.2) vs. 2.0 (1.5, 3.0) ng/ml, P = 0.022] than nonblack participants. After 48 weeks of VitD/calcium supplementation, bioavailable 25-(OH)D increased more in black than nonblack participants, but there were no between-race differences change in bone turnover markers or bone mineral density. The associations between increases in 25-(OH)D levels and change in bone outcomes appeared similar for both total and bioavailable 25-(OH)D.
Conclusion:
Baseline and change in bioavailable 25-(OH)D were higher among black adults initiating antiretroviral therapy with VitD/calcium; however, associations between 25-(OH)D and bone outcomes appeared similar for total and bioavailable 25-(OH)D. The assessment of total 25-(OH)D may be sufficient for evaluation of VitD status in black HIV-infected individuals.
Trial Registration Number:
NCT01403051.
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