biostudies-literatureWise SAIntramural NIH HHSNational Institutes of Health Office of the Director105917https://www.ebi.ac.uk/biostudies/studies/S-EPMC8403635biostudies-literatureUnknown212An intralaboratory study assessing assay variability and bias for determination of serum total 25-hydroxyvitamin D [25(OH)D] was conducted by the Vitamin D Standardization Program (VDSP). Thirteen assays for serum total 25(OH)D were evaluated in a single laboratory including 11 unique immunoassays and one liquid chromatography - tandem mass spectrometry (LC-MS/MS) assay. Fifty single-donor serum samples, including eight samples with high concentrations of 25(OH)D₂ (> 30 nmol/L), were assigned target values for 25(OH)D₂ and 25(OH)D₃ using reference measurement procedures (RMP). Using four replicate measurements for each sample, the mean total percent coefficient of variation (%CV) and mean % bias from the target values were determined for each assay using thThe Journal of steroid biochemistry and molecular biologyVitamin D Standardization Program (VDSP) intralaboratory study for the assessment of 25-hydroxyvitamin D assay variability and bias.PMC8403635Z99 OD999999Camara JEHahm GSempos CTWise SABurdette CQCavalier EMerkel JNalin FPeeters SLe Goff CDurazo-Arvizu RALukas PKuszak AJfalseVitamin D Standardization Program (VDSP) intralaboratory study for the assessment of 25-hydroxyvitamin D assay variability and bias.An intralaboratory study assessing assay variability and bias for determination of serum total 25-hydroxyvitamin D [25(OH)D] was conducted by the Vitamin D Standardization Program (VDSP). Thirteen assays for serum total 25(OH)D were evaluated in a single laboratory including 11 unique immunoassays and one liquid chromatography - tandem mass spectrometry (LC-MS/MS) assay. Fifty single-donor serum samples, including eight samples with high concentrations of 25(OH)D₂ (> 30 nmol/L), were assigned target values for 25(OH)D₂ and 25(OH)D₃ using reference measurement procedures (RMP). Using four replicate measurements for each sample, the mean total percent coefficient of variation (%CV) and mean % bias from the target values were determined for each assay using th2021-01-01T00:00:00Z2021 Sep2025-04-04T09:37:37.277Z2025-04-04T09:37:37.277ZS-EPMC84036353401068710.1016/j.jsbmb.2021.105917