An evaluation of automated methods for measurement of serum 25-hydroxyvitamin D

Objectives: To compare two new automated assays with the well-established reference method, DiaSorin radioimmunoassay (RIA), for quantitation of serum total 25-hydroxyvitamin D [25(OH)D]. Methods: 25(OH) D from human sera (n=158) was measured using DiaSorin RIA and two automated platforms, DiaSorin LIAISON 25 OH Vitamin D TOTAL, and Roche Modular Vitamin D3 (25-OH). Methods were compared by regression and Bland-Altman analyses. Results: DiaSorin LIAISON demonstrated a stronger correlation (r=0.918) and better agreement (bias=-0.88 nmol/L) with DiaSorin RIA than the Roche Modular assay (r=0.871, bias=-2.55 nmol/L). Precision ranges (CV%) for the RIA, LIAISON, and Roche Modular assays, respectively, were: within run (6.8-12.9%, 2.8-8.1%, and 1.9-5.5%), and total precision (7.4-14.5%, 7.3-17.5%, and 7.6-14.5%). Conclusion: DiaSorin LIAISON displayed the best correlation and agreement with DiaSorin RIA. The DiaSorin LIAISON 25 OH Vitamin D TOTAL assay is an accurate and precise automated tool for serum total 25(OH) D determination. (C) 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.