Increased plasma concentrations of vitamin D metabolites and vitamin D binding protein in women using hormonal contraceptives: a cross-sectional study
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UNLABELLED: Use of hormonal contraceptives (HC) may influence total plasma concentrations of vitamin D metabolites. A likely cause is an increased synthesis of vitamin D binding protein (VDBP). Discrepant results are reported on whether the use of HC affects free concentrations of vitamin D metabolites.
AIM: In a cross-sectional study, plasma concentrations of vitamin D metabolites, VDBP, and the calculated free vitamin D index in users and non-users of HC were compared and markers of calcium and bone metabolism investigated.
RESULTS: 75 Caucasian women aged 25-35 years were included during winter season. Compared with non-users (n = 23), users of HC (n = 52) had significantly higher plasma concentrations of 25-hydroxyvitamin D (25OHD) (median 84 interquartile range: [67-111] vs. 70 [47-83] nmol/L, p = 0.01), 1,25-dihydroxyvitamin D (1,25(OH)2D) (198 [163-241] vs. 158 [123-183] pmol/L, p = 0.01) and VDBP (358 [260-432] vs. 271 [179-302] µg/mL, p < 0.001). However, the calculated free indices (FI-25OHD and FI-1,25(OH)2D) were not significantly different between groups (p > 0.10). There were no significant differences in indices of calcium homeostasis (plasma concentrations of calcium, parathyroid hormone, and calcitonin, p > 0.21) or bone metabolism (plasma bone specific alkaline phosphatase, osteocalcin, and urinary NTX/creatinine ratio) between groups.
IN CONCLUSION: Use of HC is associated with 13%-25% higher concentrations of total vitamin D metabolites and VDBP. This however is not reflected in indices of calcium or bone metabolism. Use of HC should be considered in the interpretation of plasma concentrations vitamin D metabolites.
Original language | English |
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Journal | Nutrients |
Volume | 5 |
Issue number | 9 |
Pages (from-to) | 3470-80 |
Number of pages | 11 |
ISSN | 2072-6643 |
DOIs | |
Publication status | Published - 5 Sep 2013 |
- Adult, Bone Density, Calcitonin, Calcium, Contraceptive Agents, Female, Contraceptives, Oral, Hormonal, Cross-Sectional Studies, European Continental Ancestry Group, Female, Humans, Parathyroid Hormone, Seasons, Vitamin D, Vitamin D-Binding Protein, Journal Article, Research Support, Non-U.S. Gov't
Research areas
ID: 168819291