Marked Underestimation of Serum 25-hydroxyvitamin D Concentrations by The Abbot Architect Chemiluminescent Microparticle Immunoassay in Patients Receiving Vitamin D2 Supplementation

There are several methods of measurement for serum 25-hydroxyvitamin D [25(OH)D] concentration, including the gold standard liquid chromatography tandem mass spectrometry (LC-MS/MS), as well as immunoassays and high-performance liquid chromatography. Some variability in the detectability of 25(OH)D2 and 25(OH)D3 across the methods has been noted.1–5 The most frequently used assays in general clinical practice are automated immunoassays, owing to...