Performance evaluation of Siemens ADVIA Centaur and Roche MODULAR Analytics E170 Total 25-OH Vitamin D assays

► We evaluated the MODULAR E170 and the ADVIA Centaur Total Vitamin D assays. ► Both assays demonstrated acceptable linearity, imprecision, and accuracy. ► The E170 assay demonstrated consistent underestimation of 25-OH vitamin D2 levels. ► The ADVIA Centaur assay demonstrated a smaller average bias than the E170 assay. ► The ADVIA Centaur assay needs to improve its analytical precision and interference.