ArticleAnalytical and bioanalytical chemistry2022
Towards harmonization of directly measured free 25-hydroxyvitamin D using an enzyme-linked immunosorbent assay.
Article in Analytical and bioanalytical chemistry, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers.
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7 citing papers in PubMed, 12 citations in OpenAlex.
- Advances in the measurement of vitamin D binding protein.Analytical and bioanalytical chemistry · 2026Review
- Review
- Sensitive and Facile Detection of Vitamin D Based on Fluorescent Labeled Aptamer Probe and Exonuclease I-Assisted Signal Amplification.Journal of fluorescence · 2025Article
- Article
- Reference Materials for Improving Reliability of Multiomics Profiling.Phenomics (Cham, Switzerland) · 2024Review
- Evolution and impact of Standard Reference Materials (SRMs) for determining vitamin D metabolites.Analytical and bioanalytical chemistry · 2024Review
- A novel LC-MS/MS method combined with derivatization for simultaneous quantification of vitamin D metabolites in human serum with diabetes as well as hyperlipidemia.RSC advances · 2023Article
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Authors and funding
9 authors at 5 institutions in 4 countries.
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Abstract
The majority of circulating 25-hydroxyvitamin D (25(OH)D) is protein bound and perhaps less available than the free fraction of 25(OH)D; therefore, researchers have proposed that the measurement of free 25(OH)D in human serum may be a better indicator of vitamin D health status than total 25(OH)D. The availability of a new enzyme-linked immunosorbent assay (ELISA) for the determination of free 25(OH)D provides a method for direct measurement of the low levels of non-protein bound 25(OH)D. As an initial step towards harmonization of measurements of free 25(OH)D, the ELISA was used to measure free 25(OH)D in three existing Standard Reference Materials (SRMs): SRM 972a Vitamin D Metabolites in Frozen Human Serum, SRM 2973 Vitamin D Metabolites in Frozen Human Serum (High Level), and SRM 1949 Frozen Prenatal Human Serum. Target values for free 25(OH)D in the nine SRM serum pools, obtained by combining the results from two laboratories, ranged from 3.76 ± 0.36 to 10.0 ± 0.58 pg/mL. Of particular significance is the assignment of free 25(OH)D target values to SRM 1949, which consists of four serum pools from non-pregnant female donors of reproductive age and pregnant women in each of the three trimesters and which also has values assigned for vitamin D binding protein, which increases during pregnancy. The availability of target values for free 25(OH)D in these SRMs will allow researchers to validate new analytical methods and to compare their results with other researchers as an initial step towards harmonization of measurements among different studies and laboratories.
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