Harmonization Study Between LC-MS/MS and Diasorin RIA for Measurement of 25-Hydroxyvitamin D Concentrations in a Large Population Survey

BACKGROUND: Population-based research on vitamin D has increased dramatically in recent years. Such studies are typically reliant on assay procedures to measure reliable and comparable levels of 25-hydroxyvitamin D [25(OH)D] concentrations. METHODS: Concentrations of 25(OH)D3 and 25(OH)D2 were measu...

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Bibliographic Details
Main Authors: Berry, DJ, Dutton, J, Fraser, WD, Järvelin, MR, Hyppönen, E
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
25(OH)D
assay
limits of agreement
population study
reliability
replication
vitamin D
Northern Finland
Online Access:https://discovery.ucl.ac.uk/id/eprint/1514947/1/Berry_et_al-2016-Journal_of_Clinical_Laboratory_Analysis.pdf
https://discovery.ucl.ac.uk/id/eprint/1514947/
Description
Summary:BACKGROUND: Population-based research on vitamin D has increased dramatically in recent years. Such studies are typically reliant on assay procedures to measure reliable and comparable levels of 25-hydroxyvitamin D [25(OH)D] concentrations. METHODS: Concentrations of 25(OH)D3 and 25(OH)D2 were measured using LC-MS/MS in 5,915 participants (aged 31 years) of Northern Finland Birth Cohort 1966. Blood samples were assayed in batches over a course of 18 months. As anomalies were present in the measurements, 200 samples were reassayed using Diasorin RIA. Agreement between measurements was assessed by Passing-Bablok regression and limits of agreement (LoA). To harmonize LC-MS/MS with Diasorin RIA measurements, formulae were derived from the LoA. RESULTS: Concentrations measured by LC-MS/MS were much higher than those measured by Diasorin RIA, with a mean difference of 12.9 ng/ml. Constant variation was evident between batch measurements after log transformation. Statistical formula was applied separately for each batch of LC-MS/MS measurements, enabling us to remove both the constant and proportional bias that was evident prior to the transformation. CONCLUSION: Despite the introduction of schemes/programs to improve accuracy of assays to measure 25(OH)D, significant differences can still happen. In these instances, methods to harmonize measurements based on a relatively small number of replicates can be successfully applied to establish confidence and to enable between-study comparisons.

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