The Journal of Clinical Endocrinology & Metabolism May 14, 2012 jc.2011-3401
Lan-Juan Zhao, Yu Zhou, Fengxiao Bu, Dianne Travers-Gustafson, An Ye, Xiaojing Xu, Lee Hamm, Daniel Michael Gorsage, Xiang Fang, Hong-Wen Deng, Robert R. Recker and Joan M. Lappe
Department of Biostatistics and Bioinformatics (L.-J.Z., Y.Z., A.Y., X.X., H.-W.D.), Center for Bioinformatics and Genomics, and Department of Medicine (L.H.), Tulane University, New Orleans, Louisiana 70112; and Osteoporosis Research Center (L.-J.Z., Y.Z., F.B., D.T.-G., A.Y., X.X., D.M.G., X.F., R.R.R., J.M.L.), Creighton University, Omaha, Nebraska 68131
Address all correspondence and requests for reprints to: Lan-Juan Zhao, Ph.D., Center for Bioinformatics and Genomics, Department of Biostatistics and Bioinformatics, Tulane University, 1440 Canal Street, Suite 2001, New Orleans, Louisiana 70112. E-mail: lzhao2 at tulane.edu.
Objective: It is well documented that there is wide variation in the response of serum 25-hydroxyvitamin D [25(OH)D] to a given dose of vitamin D supplementation. Understanding factors affecting the response variation is important for identifying subjects who are susceptible to vitamin D deficiency or toxicity. This study aimed to evaluate potential predictors for vitamin D response variation.
Design and Participants: A total of 1179 non-Hispanic white postmenopausal women were enrolled into a 4-yr calcium and vitamin D (1100 IU/d) clinical trial. Among them, serum 25(OH)D level of 1063 subjects were measured at both baseline and after 12 months treatment. Vitamin D response was computed for these 1063 subjects as the difference in levels of serum 25(OH)D concentration at the end of a 12-month vitamin D treatment compared with baseline. Stepwise linear regression was used to identify predictors of vitamin D response variation.
- Increase in vitamin D intake,
- baseline serum 25(OH)D level,
- baseline blood collection season,
- baseline serum calcium level, and
- baseline body mass index
were predictors of vitamin D response variation.
These five factors explained 46.8% of the vitamin D response variation in the 1063 subjects.
The first three factors [[increase in vitamin D intake, baseline serum 25(OH)D level, baseline blood collection season] remained as predictors in the 392 subjects with trial vitamin D supplementation.
For the first time, our study indicated that season is an important prediction factor for vitamin D response variation.
Subjects who started vitamin D treatment in a cold season (autumn and winter) achieved a significantly higher serum 25(OH)D increase than those started in a hot season (summer) (P < 0.001).
Conclusion: Our study suggests that the increase in vitamin D supplementation, baseline serum 25(OH)D level, and the season when initiating the vitamin D supplementation can partially predict vitamin D response variation in non-Hispanic postmenopausal women.
Received December 19, 2011; Accepted April 25, 2012.
Copyright © 2012 by The Endocrine Society
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RED square = reduction in serum level
from slide presentation: http://www.vitamindwiki.com/tiki-index.php?page_id=2269