Analytical performance of a single epitope meta-sandwich total 25-hydroxyvitamin D immunoassay and establishment of reference intervals in a Chinese population

BACKGROUND: 25-hydroxyvitamin D [25-(OH)D] concentration is considered to evaluate vitamin D status. Persistent discrepancies between chemiluminescent immunoassays (CLIAs) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) continue to challenge clinical laboratories. To investigate the single epitope meta-sandwich (SEMS) immunoassay from Mindray, we performed an assessment of VD-T Ⅱ assay on the analytical performance, and the reference intervals establishment. METHODS: We performed detection limits, precision, linearity, cross reactivity studies according to American Clinical and Laboratory Standards Institute (CLSI) protocols, measured 118 selected serum samples with Mindray VD-T Ⅱ (CLIA). The results were compared with those obtained with LC-MS/MS and three other automated 25-(OH)D assays (Roche, Abbott, Snibe). Additionally, season-stratified 95% reference intervals in adults and age-specific 95% reference intervals in children of VD-T Ⅱ assay from 1402 healthy individuals are determined. RESULTS: The LoB, LoD and LoQ all met the claimed range; within-run and within-laboratory precision coefficient of variation (CV%) for VD-T Ⅱ was between 1.64% and 2.36%, 3.08% and 6.32% respectively; a good linearity was found in linear range from 3.00ng/mL to 150.00 ng/mL. The correlation coefficient of VD-T Ⅱ compared with LC-MS/MS was 0.963, which was the highest correlation among the assays tested; In adults, the 95% reference intervals were 7.86-48.56 ng/mL in summer, 6.28-43.34 ng/mL in winter; in children, the 95% reference intervals were 3.76-43.34 ng/mL, 6.56-50.47 ng/mL and 4.66-29.22 ng/mL in < 1 years old, 1-13 years old and 14-18 years old groups. CONCLUSIONS: The Mindray VD-T Ⅱ assay is suitable for routine total 25-(OH)D testing.