Journal Information
Journal ID (publisher-id): BM
Journal ID (nlm-ta): Biochem Med (Zagreb)
Title: Biochemia Medica
Abbreviated Title: Biochem. Med. (Zagreb)
ISSN (print): 1330-0962
ISSN (electronic): 1846-7482
Publisher: Croatian Society of Medical Biochemistry and Laboratory Medicine
Article Information
Copyright statement: ©Croatian Society of Medical Biochemistry and Laboratory Medicine.
Copyright: 2021, Croatian Society of Medical Biochemistry
License (open-access):
This is an Open Access article distributed under the terms of the Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Date received: 08 February 2021
Date accepted: 12 June 2021
Publication date (electronic): 05 August 2021
Publication date (print): 15 October 2021
Volume: 31
Issue: 3
Electronic Location Identifier: 030701
Publisher ID: bm-31-3-030701
DOI: 10.11613/BM.2021.030701
Comparison of Freelite and N-Latex serum free light chain assays: a critical review
Vincenzo Roccaforte[4]
Giuseppe Lippi[5]
[1] Clinical Biochemical Laboratory, Hospital of Bolzano, Bolzano, Italy
[2] Northern Ireland Blood Transfusion Service (NIBTS), Belfast, United Kingdom
[3] Department of Internal Medicine V, University of Innsbruck, Innsbruck, Austria
[4] Clinical Pathology Laboratory, Hospital Alessandro Manzoni, Lecco, Italy
[5] Section of Clinical Biochemistry, Verona University of Verona, Verona, Italy
Author notes:
[*] Corresponding author: massimo.daves@sabes.it
Introduction
The measurement of serum free light chain (FLC) represents a fundamental aspect on the assessment of patients with monoclonal gammopathies (MG). Different analytical methods for FLC have become available with the possibility to obtain different value with a substantial impact on the assessment of patients with MG. This study aimed to evaluate FLC results obtained with two different assays and how the difference value obtained can impact in the patient’s assessment.
Materials and methods
Ninety-three patient serum samples that underwent analysis for FLC with two different methods, Serum Freelite (The Binding Site, Birmingham, UK) and N-Latex FLC (Siemens, Marburg, Germany), were included in this retrospective study. Statistical analysis was performed to evaluate correlation, difference, and the grade of concordance between the results obtained with the two methods.
Results
Significant statistical differences between the results obtained from the two methods were found (P < 0.05). A good correlation was found (0.99 for κ FLC, 0.95 for λ FLC, and 0.94 for the κ/λ ratio, respectively). We found a weighted kappa value of 0.65 for κ/λ ratio, 0.65 for λ FLC and 0.90 for κ FLC. A positive bias found with the Bland-Altman plot mirrors overestimation of κ FLC and κ/λ ratio with Freelite compared to N-Latex, whilst a negative bias underscores underestimation of λ FLC by Freelite compared to N-Latex.
Keywords: free light chain; monoclonal gammopathies; analytical techniques and equipment; comparison; immunoassays