Egner, W., Swallow, K., Lock, R.J. et al. (1 more author) (2016) Falsely low IgG4 in routine analysis - How not to miss IgG4 disease. Clinical & Experimental Immunology, 186 (1). pp. 57-63. ISSN 0009-9104
Abstract
Background IgG4 disease can have apparently “normal” levels of IgG4 due to antigen excess conditions. IgG4 measurement therefore appears falsely low. UK NEQAS data and other reports have suggested this problem occurred despite pre-existing antigen excess detection steps. Methods We examined the prevalence and characteristics of prozoning in our laboratory and patient cohorts, to determine the clinical relevance of the problem. Results We establish that the prevalence of raised IgG4 in routine IgG4 analysis is low (<1%) using one of the 2 routine methods in use in the UK. We show that subsequent assay modification appears to have reduced the likelihood of misleading readings. However, the original version of the assay prozoned to low levels (below 0.64g/L) in 41% of high IgG4 samples in our patients. This may explain the previous reports of low sensitivity of raised IgG4 for IgG4RD, and predictive values should be re-evaluated in this disease using modified prozone-resistant protocols. Conclusions All laboratories providing IgG4 measurements should verify that their assays are fit for the clinical quality requirement of detection raised IgG4 levels and must verify the upper limit of their reference ranges and freedom from prozoning.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016 Wiley. This is an author-produced version of a paper accepted for publication in Clinical and Experimental Immunology. Uploaded in accordance with the publisher's self-archiving policy |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Medicine, Dentistry and Health (Sheffield) > The Medical School (Sheffield) The University of Sheffield > Sheffield Teaching Hospitals |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 11 Jul 2016 13:32 |
Last Modified: | 18 Jul 2017 06:26 |
Published Version: | http://dx.doi.org/10.1111/cei.12805 |
Status: | Published |
Publisher: | Wiley |
Refereed: | Yes |
Identification Number: | 10.1111/cei.12805 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:102237 |