English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Background: Measurement of 25-hydroxyvitamin D2 and D3 (25-OH D2 and D3) is essential for investigating vitamin D deficiency. Competitive binding techniques are unable to distinguish between the 2 metabolites and suffer from interference from other hydroxy metabolites of vitamin D. Methods: We used isotope-dilution liquid chromatography–tandem mass spectrometry (ID-LC-MS/MS) for routine determination of 25-OH D2 and D3 with a stable-isotope–labeled internal standard (IS). Serum samples (100 μL) were denatured with methanol–propanol containing IS, vortex-mixed, extracted into hexane, and dried under nitrogen. The reconstituted extract was chromatographed on a BDS C8 HPLC column, and the metabolites and IS were detected by electrospray ionization MS/MS in multiple-reaction monitoring mode. Results: 25-OH D2 and D3 and the IS nearly coeluted, whereas 1α-hydroxyvitamin D3 was separated; total run time was 8 min. The interassay CVs for 25-OH D2 were 9.5% and 8.4% at 52 and 76 nmol/L, respectively, and for 25-OH D3 were 5.1% and 5.6% at 55 and 87 nmol/L, respectively. The detection limit of the present method was &amp;lt;4 nmol/L for both metabolites. Method comparison with a commercial RIA measuring total 25-hydroxyvitamin D showed good correlation: y = 0.97x − 2.7 nmol/L (r = 0.91). The analytical system can assay 100 samples in 12.5 h. Conclusions: This simple robust interference-free LC-MS/MS assay is suitable for routine measurement of the 25-hydroxy metabolites of vitamins D2 and D3 in human serum. The assay has been in use for 9 months and has been used to assay more than 6000 routine samples.

clinical chemistry

Routine Isotope-Dilution Liquid Chromatography–Tandem Mass Spectrometry Assay for Simultaneous Measurement of the 25-Hydroxy Metabolites of Vitamins D2 and D3