Evaluation of two automated immunoassays for 25-OH vitamin D: Comparison against LC-MS/MS

▸ Two automated 25-OHD immunoassay methods were compared against LC-MS/MS. ▸ Serum specimens contained endogenous 25-OHD2 to challenge immunoassay specificity. ▸ The DiaSorin method demonstrated better precision than the Siemens method. ▸ The DiaSorin LIAISON® method agreed with LC-MS/MS. ▸ Substantial bias was observed in the Siemens ADVIA Centaur® method.