Dirks NF, Martens F, Vanderschueren D, Billen J, Pauwels S, Ackermans MT, Endert E, Heijer MD, Blankenstein MA, Heijboer AC. Determination of human reference values for serum total 1,25-dihydroxyvitamin D using an extensively validated 2D ID-UPLC-MS/MS method.
J Steroid Biochem Mol Biol 2016;
164:127-133. [PMID:
26690787 DOI:
10.1016/j.jsbmb.2015.12.003]
[Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 10/15/2015] [Accepted: 12/06/2015] [Indexed: 01/18/2023]
Abstract
BACKGROUND
To assess a patient's vitamin D status the precursor metabolite 25-hydroxyvitamin D can be determined. However, measurement of 1,25-dihydroxyvitamin D is required when disorders of 1a-hydroxylation, extrarenal 1a-hydroxylation, or vitamin D receptor defects are suspected.
METHODS
The aim of this study was to determine reference values for 1,25-dihydroxyvitamin D3 and D2 using a 2D ID-UPLC-MS/MS method.
RESULTS
The LC-MS/MS method, able to measure picomolar concentrations of both 1,25-dihydroxyvitamin D3 and D2 in human serum, was extensively validated. Intra-assay variations were <5% and 8.5% and <7.5% and 11%, for 1,25-dihydroxyvitamin D3 and D2, respectively, over the whole dynamic range (3.1-376 and 3.1-652pmol/L). Limit of quantitation was 3.4pmol/L for both compounds. Our method correlated well with a published LC-MS/MS method (r=0.87) and with the average 1,25-dihydroxyvitamin D3 results of the vitamin D External Quality Assessment Scheme (DEQAS) determined with LC-MS/MS (r=0.93). Reference ranges, determined in 96 plasma samples of healthy volunteers were 59-159pmol/L and <17pmol/L for respectively 1,25-dihydroxyvitamin D3 and D2. The female part of the reference group showed a statistically significant decrease of 1,25-dihydroxyvitamin D3 concentrations with age. The presence of significantly higher average 1,25-dihydroxyvitamin D3 levels in premenopausal women taking oral contraceptive pills compared to postmenopausal women suggests that this effect is estrogen-related, as estrogens lead to a higher vitamin D binding protein.
CONCLUSIONS
The major finding of the present study is a reference interval of 59-159pmol/L for 1,25-dihydroxyvitamin D3 determined with a highly sensitive and precise LC-MS/MS method.
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