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Updated: Jul 25, 2025
Homogeneous Time-resolved Förster Resonance Energy Transfer-based Assay for Detection of Insulin Secretion
Published on: May 10, 2018
Beyond the method change in clinical practice: evaluation of insulin-like growth factor I assay
Paula Sienes Bailo1, Marta Fabre Estremera1, José Cuenca Alcocel2
1Department of Clinical Biochemistry, Miguel Servet University Hospital, Zaragoza, Spain; and Aragon Institute of Health Research (IIS Aragon), Zaragoza, Spain.
Objectives:
Insulin-like growth factor I (IGF-I) is the preferred biomarker for diagnosing and monitoring growth-related disorders but its serum quantification presents several difficulties since different IGF-I assays still leads to different IGF-I concentrations, especially when results are either above or below the normal range.
Methods:
We conducted a prospective study between November and December 2020 at a tertiary University Hospital with 212 serum samples to determine the analytical performance of the IGF-I assay on the Cobas e411 (Roche Diagnostics) and compare it with that of the Immulite 2000XPi (Siemens).
Results:
In this work, we report for the first time the existence of discrepancies between IGF-I levels measured by Immulite 2000XPi and Cobas e411. Deming regression model provided a slope of 1.570 (95% CI: 1.395-1.745) and an intercept of -58.591 (95% CI: -89.151 to -28.030), with R2=0.967 and average bias of +53.061 with overestimation of IGF-I. It was found that Cobas e411 provides abnormally high IGF-I concentrations, but further studies are required to elucidate the cause of the discrepancies.
Conclusions:
Our data can alert clinicians and laboratory professionals of this situation and avoid misinterpretation of increased IGF-I levels as a therapeutic failure rather than as a problem associated with this method change.
