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Vitamin D Standardization Program (VDSP) intralaboratory study for the assessment of 25-hydroxyvitamin D assay variability and bias



Johanna Camara, Stephen Wise, Christopher T. Sempos, Pierre Lukas, Caroline LeGoff, Stephanie Peeters, Carolyn Burdette, Federica Nalin, Grace Hahm, Ramon Durazo-Arvizu, Adam J. Kuszak, Joyce M. Merkel, E. Cavalier


An intralaborabory comparison study to assess the performance of assays for the determination of serum total 25-hydroxyvitamin D [25(OH)D] was conducted in 2017 as part of the Vitamin D Standardization Program (VDSP). The intralaboratory study consisted of the evaluation of 13 assays in a single laboratory including 11 different immunoassays and one liquid chromatography – tandem mass spectrometry (LC-MS/MS) assay. The assays were used to determine serum total 25(OH)D, which is defined as the sum of 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3], in 50 single-donor serum samples. The 50 single-donor samples, which included 8 samples with high concentrations of 25(OH)D2, were analyzed at the National Institute of Standards and Technology (NIST) using reference measurement procedures to assigned target values for 25(OH)D2, 25(OH)D3, 3- epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3], and 24R,25-dihydroxyvitamin D3 [24,25(OH)2D3]. For each assay, duplicate measurements were performed on two separate days (n = 4) for each of the 50 single-donor serum samples (i.e., total of 200 measurements per assay). The mean total coefficient of variation (%CV) and the mean % bias from the target values were determined for each assay and compared with the VDSP performance criteria of ≤ 10 % CV and ≤ ±5 % mean % bias. All 13 assays met the performance criterion for %CV and 9 of the 13 assays were within ≤ ±5 % mean % bias. Only three immunoassays (Beckman Coulter, Fujirebio Inc, and Diazyme) and the LC-MS/MS assay were minimally affected by the inclusion of the high 25(OH)D2 single-donor samples. The remaining nine immunoassays exhibited deviations (some as great as 30 %) in the linear regression analysis due to the high concentration 25(OH)D2 samples indicating that these assays may not have equivalent responses for both 25(OH)D2 and 25(OH)D3 as assumed or promoted. The Fujirebio Inc. assay exhibited the lowest %CV, highest % of individual measurements within ±
Journal of Steroid Biochemistry and Molecular Biology


25-hydroxyvitamin D3, 25-hydroxyvitamin D2, 3-epi-25-hydroxyvitamin D3, serum total 25-hydroxyvitamin D, liquid chromatography – tandem mass spectrometry (LC-MS/MS), immunoassay, reference measurement procedure (RMP), Vitamin D Standardization Program (VDSP)


Camara, J. , Wise, S. , Sempos, C. , Lukas, P. , LeGoff, C. , Peeters, S. , Burdette, C. , Nalin, F. , Hahm, G. , Durazo-Arvizu, R. , Kuszak, A. , Merkel, J. and Cavalier, E. (2021), Vitamin D Standardization Program (VDSP) intralaboratory study for the assessment of 25-hydroxyvitamin D assay variability and bias, Journal of Steroid Biochemistry and Molecular Biology, [online], , (Accessed May 28, 2024)


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Created May 17, 2021, Updated October 14, 2021