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Type: Journal article
Title: Differences in Recognition of the 1st WHO International Reference Reagents for hCG-Related Isoforms by Diagnostic Immunoassays for Human Chorionic Gonadotropin
Author: Sturgeon, C.
Berger, P.
Bidart, J.
Birken, S.
Burns, C.
Norman, R.
Stenman, U.
Citation: Clinical Chemistry (Washington, DC): international journal of molecular diagnostics and laboratory medicine, 2009; 55(8):1484-1491
Publisher: Amer Assoc Clinical Chemistry
Issue Date: 2009
ISSN: 0009-9147
Statement of
Catharine M. Sturgeon, Peter Berger, Jean-Michel Bidart, Steven Birken, Chris Burns, Robert J. Norman, Ulf-Håkan Stenman on behalf of the IFCC Working Group on hCG
Abstract: Background: The 1st WHO International Reference Reagents (IRRs) for 6 human chorionic gonadotropin (hCG)-related molecular variants, highly purified and calibrated in substance concentrations by the IFCC Working Group for hCG, permit experimental elucidation of what commercially available hCG methods measure in molar terms and enable assessment of their fitness for clinical purposes. Methods: Pools containing known amounts of the IRRs spiked into normal human serum were issued to participants through the UK National External Quality Assessment Service for hCG for a period of 7 years. Among 16 assays used, 4 recognized only hCG, whereas 6 recognized hCG and its free β-subunit (hCGβ), and 6 recognized hCG, hCGβ, and the beta core fragment. Results: Differences in calibration of current hCG assays are moderate. Mean recovery of the current International Standard (IS), hCG IS 75/589, was 107% (range 93% to 126%), whereas that of the IRR 99/688 for hCG was 139% (range 109%–164%). Between-method variation for the latter (CV 12.3%) was also greater than for IS 75/589 (CV 8.8%). Recognition of hCGβ varied markedly (CV 37%). Most assays overestimated it, but 2 RIAs produced results that were slight underestimations. Recognition of the beta core fragment was even more variable (CV 57%) and was closest to equimolarity for the RIAs. Conclusions: Assays for hCG show considerable variation in their recognition of various forms of hCG, and this variablility is the most important cause of method-related differences in hCG results in serum and an even more important cause of method-related differences in urine measurements. Equimolar recognition of the major hCG isoforms is essential if between-method comparability for hCG is to be improved.
Keywords: IFCC Working Group on hCG
Chorionic Gonadotropin
Chorionic Gonadotropin, beta Subunit, Human
Glycoprotein Hormones, alpha Subunit
Peptide Fragments
Protein Isoforms
Reference Standards
World Health Organization
Description: © 2009 American Association for Clinical Chemistry, Inc.
DOI: 10.1373/clinchem.2009.124578
Published version:
Appears in Collections:Aurora harvest 5
Paediatrics publications

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