Serum free and bio-available 25-hydroxyvitamin D correlate better with bone density than serum total 25-hydroxyvitamin D
Open accessAbstract
In the circulation 25-hydroxyvitamin D (25(OH)D) is bound to vitamin D-binding protein (DBP) and albumin. Only a small fraction is in the unbound, free form. According to the 'free-hormone-hypothesis' only the free form is biologically active. Genetic differences in DBP may affect the binding to 25(OH)D and thereby the amount of free 25(OH)D. In the present study sera were obtained from 265 postmenopausal women with low bone mass density (BMD). Serum 25(OH)D, DBP and albumin were measured and the free and bio-available (free + albumin-bound) 25(OH)D calculated. Based on genotyping of the polymorphisms rs7041 and rs4588, the six common DBP phenotypes were identified and the free and bio-available 25(OH)D calculated according to the corresponding binding coefficients. Relations between measures of 25(OH)D and PTH and BMD were evaluated with linear regression adjusted for age and BMI. The calculated amount of free and bio-available 25(OH)D was 0.03% and 13.1%, respectively, of the measured total serum 25(OH)D. Adjusting for DBP phenotype affected the calculated free and bio-available 25(OH)D levels up to 37.5%. All measures of 25(OH)D correlated significantly with PTH, whereas a significant association with BMD was only seen for the free and bio-available 25(OH)D measures. Adjusting for the DBP phenotypes improved the associations. These relations were almost exclusively seen in subjects not using vitamin D and/or calcium supplements. In conclusion, the free and bio-available fo…
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Free 25(OH)D is more appropriate than total 25(OH)D for assessing vitamin D status when DBP levels are altered (CKD, obesity, liver problems).
“Valorization of a patient’s vitamin D status in clinical settings where DBP levels are altered, such as CKD, obesity and liver problems, has also been deemed more appropriate when using free serum 25(OH)D as compared to total serum 25(OH)D [243–246].”
From Role of sex hormone-binding globulin in the free hormone hypothesis and the relevance of free testosterone in androgen physiology (2022) · cites this paper as [244]
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Narinx, N., David, K., Walravens, J., Vermeersch, P., Claessens, F., Fiers, T., Lapauw, B., Antonio, L., & Vanderschueren, D. (2022) · Cellular and Molecular Life Sciences · doi:10.1007/s00018-022-04562-1 · Cited by 96 · see citing works
- Authors
- Johnsen, M. S., Grimnes, G., Figenschau, Y., Torjesen, P. A., Almås, B., & Jorde, R.
- Affiliations
- UiT The Arctic University of Norway (NO)
- University Hospital of North Norway (NO)
- Oslo University Hospital (NO)
- Haukeland University Hospital (NO)
- Corresponding author
- Jorde, Rolf
- Venue
- Scandinavian Journal of Clinical and Laboratory Investigation
- Publisher
- Informa UK Limited
- Published
- 2014-01-02
- Volume
- 74
- Issue
- 3
- Pages
- 177-183
- ISSN
- 0036-5513 (ISSN-L)
- 1502-7686
- OpenAlex
- W2081357257
- Cited by
- 112
- References
- 5
- Citations by year
- 2025: 5 · 2024: 5 · 2023: 3 · 2022: 6 · 2021: 11 · 2020: 9 · 2019: 6 · 2018: 18 · 2017: 18 · 2016: 17 · 2015: 9 · 2014: 5
- FWCI
- 12.15
- Type
- journal article
- Language
- en
- Update notices
- correction (2014-08-14)
- Open access
- green
- hdl.handle.net
- Licence
- cc-by-nc-sa
- Locations
- Scandinavian Journal of Clinical and Laboratory Investigation (publishedVersion)
- PubMed (publishedVersion)
- NORA - Norwegian Open Research Archives (submittedVersion, cc-by-nc-sa)
- Funders
- Nasjonalforeningen for Folkehelsen
- Topics
- Health Sciences › Medicine › Pathology and Forensic Medicine › Vitamin D Research Studies
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Bone health and osteoporosis research
- Health Sciences › Medicine › Nephrology › Parathyroid Disorders and Treatments
- Keywords
- 25-hydroxyvitamin D, free vitamin D, bioavailable vitamin D, vitamin D binding protein, rs7041, rs4588, bone mineral density, postmenopausal women, osteopenia, parathyroid hormone, vitamin D status, vitamin D supplementation
- MeSH terms
- Aged, Aged, 80 and over, Biological Availability, Female, Genotype, Humans, Middle Aged, Parathyroid Hormone, Phenotype, Polymorphism, Genetic, Serum Albumin, Vitamin D, Vitamin D-Binding Protein, Bone Density, Postmenopause
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