Current 25-hydroxyvitamin D assays: Do they pass the test?

► Five 25-hydroxyvitamin D (25OHD) assays were compared. ► Four 25OHD assays were evaluated using accuracy and precision data. ► The imprecision of quality control samples for the immunoassays was all below 10%. ► The imprecision of pooled serum samples for immunoassays was between 2.7% and 22.8%. ► Based on stringent analytical goals, most 25OHD assays did not meet the standards.