Abstract
Total serum 25(OH)D is used clinically as a biomarker for vitamin D status. However, the biochemistry of its transportation, the features of its metabolism, and the mechanisms of its entry into different cell types combine to complicate its designation as the best biomarker of vitamin D sufficiency. Vitamin D-binding protein is the major transport protein of vitamin D metabolites, and it has been proposed that the small portion of 25(OH)D that is unbound (free 25(OH)D) or bound only to albumin (bioavailable 25(OH)D) could be relevant measures of vitamin D status. This chapter reviews the concepts behind free and bioavailable 25(OH)D, the studies that suggest their possible importance, the new assays that are used to measure or estimate them, and the clinical and epidemiologic studies that have evaluated them. The likely utility of these biomarkers is evaluated based on current knowledge, and prospects for the future are offered.
| Original language | English (US) |
|---|---|
| Title of host publication | Biochemistry, Physiology and Diagnostics |
| Publisher | Elsevier Inc. |
| Pages | 925-937 |
| Number of pages | 13 |
| Volume | 1 |
| ISBN (Electronic) | 9780128099667 |
| ISBN (Print) | 9780128099650 |
| DOIs | |
| State | Published - 2018 |
Keywords
- Albumin
- Bioavailable 25-hydroxyvitamin D
- Free 25-hydroxyvitamin D
- Total 25-hydroxyvitamin D
- Vitamin D-binding protein
ASJC Scopus subject areas
- General Agricultural and Biological Sciences
- General Biochemistry, Genetics and Molecular Biology
- General Medicine