Bias in IGF-1 concentrations and interpretation across three different clinical laboratory assays

Zahraa Mohammed-Ali; Sarah Delaney; Ravinder Singh; Felix Leung; Jennifer Taher; Jeannette Goguen; Julie Gilmour; Lusia Sepiashvili; Daniel R Beriault

doi:10.1016/j.clinbiochem.2022.06.009

Bias in IGF-1 concentrations and interpretation across three different clinical laboratory assays

Clin Biochem. 2022 Oct:108:14-19. doi: 10.1016/j.clinbiochem.2022.06.009. Epub 2022 Jun 27.

Authors

Zahraa Mohammed-Ali¹, Sarah Delaney², Ravinder Singh³, Felix Leung⁴, Jennifer Taher⁴, Jeannette Goguen⁵, Julie Gilmour⁵, Lusia Sepiashvili⁶, Daniel R Beriault⁷

Affiliations

¹ Department of Laboratory Medicine, St. Michael's Hospital, Toronto, ON, Canada. Electronic address: [email protected].
² Department of Laboratory Medicine, St. Michael's Hospital, Toronto, ON, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
³ Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
⁴ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada; Department of Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada.
⁵ Department of Medicine, Division of Endocrinology and Metabolism, St. Michael's Hospital, Toronto, ON, Canada.
⁶ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada; The Hospital for Sick Children, Toronto, ON, Canada.
⁷ Department of Laboratory Medicine, St. Michael's Hospital, Toronto, ON, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada; Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.

PMID: 35772500
DOI: 10.1016/j.clinbiochem.2022.06.009

Abstract

In this study, we compared the DiaSorin LiaisonXL IGF-1 immunoassay to both the Roche Elecsys IGF-1 immunoassay and to the liquid chromatography-high resolution mass spectrometry (LC-MS) IGF-1 assay. Our study shows a constant positive bias in DiaSorin compared to the Roche immunoassay (mean 42 μg/L, 24%), and a proportional positive bias in DiaSorin compared to the LC-MS method (mean 49 μg/L, 29%). Further, we demonstrate the potential clinical impact of this bias by evaluating 43 adult samples, collected over a 2-month period, which were shown to be discrepant based on a chart review. Despite the positive analytical bias in the Diasorin assay compared to the LC-MS assay, the Diasorin assay upper reference limits were lower than those of the LC-MS assay. This effect caused nine out of forty-three samples to show falsely elevated results when they were clinically diagnosed as negative for acromegaly. Discussed in the context of previous literature, our findings emphasize the importance of adjusting reference intervals for IGF-1 assays based on the clinical needs of a patient population.

Keywords: Acromelagy; Diasorin Liaison XL; Giagantism; IGF-1 immunoassay; LC–MS; Method comparison; Roche Elecsys.

MeSH terms

Adult
Chromatography, Liquid / methods
Humans
Immunoassay / methods
Insulin-Like Growth Factor I
Laboratories, Clinical
Tandem Mass Spectrometry* / methods
Vitamin D*

Substances

Vitamin D
Insulin-Like Growth Factor I