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Determination of 21-hydroxylase autoantibodies: inter-laboratory concordance in the Euradrenal International Serum Exchange Program

  • Alberto Falorni EMAIL logo , Vittorio Bini , Corrado Betterle , Annalisa Brozzetti , Luis Castaño , Marta Fichna , Olle Kämpe , Gunnar Mellgren , Pärt Peterson , Shu Chen , Johan Rönnelid , Jochen Seissler , Claudio Tiberti , Raivo Uibo , Liping Yu , Åke Lernmark and Eystein Husebye
Published/Copyright: March 26, 2015
Clinical Chemistry and Laboratory Medicine (CCLM)
From the journal Clinical Chemistry and Laboratory Medicine (CCLM) Volume 53 Issue 11

Abstract

Background: 21-Hydroxylase autoantibodies (21OHAb) are markers of an adrenal autoimmune process that identifies individuals with autoimmune Addison’s disease (AAD). Quality and inter-laboratory agreement of various 21OHAb tests are incompletely known. The objective of the study was to determine inter-laboratory concordance for 21OHAb determinations.

Methods: Sixty-nine sera from 51 patients with AAD and 51 sera from 51 healthy subjects were blindly coded by a randomization center and distributed to 14 laboratories that determined 21OHAb, either by an “in-house” assay (n=9) using in vitro-translated 35S-21OH or luciferase-labeled 21OH or a commercial kit with 125I-21OH (n=5). Main outcome measures were diagnostic accuracy of each participating laboratory and inter-laboratory agreement of 21OHAb assays.

Results: Intra-assay coefficient of variation ranged from 2.6% to 5.3% for laboratories using the commercial kit and from 5.1% to 23% for laboratories using “in-house” assays. Diagnostic accuracy, expressed as area under ROC curve (AUC), varied from 0.625 to 0.947 with the commercial kit and from 0.562 to 0.978 with “in-house” methods. Cohen’s κ of inter-rater agreement was 0.603 among all 14 laboratories, 0.691 among “in-house” laboratories, and 0.502 among commercial kit users. Optimized cutoff levels, calculated on the basis of AUCs, increased the diagnostic accuracy of every laboratory (AUC >0.9 for 11/14 laboratories) and increased the Cohen’s κ of inter-rater agreement. Discrepancies in quantitation of 21OHAb levels among different laboratories increased with increasing autoantibody levels.

Conclusions: The quality of 21OHAb analytical procedures is mainly influenced by selection of cutoff value and correct handling of assay materials. A standardization program is needed to identify common standard sera and common measuring units.

Keywords: Addison’s disease; adrenal antibodies; autoimmunity; diagnosis; RIA; standardization
Corresponding author: Alberto Falorni, MD, PhD, Department of Medicine, University of Perugia, Via E. Dal Pozzo, 06126 Perugia, Italy, Phone: +39-75-5783588, Fax:+39-75-5783940, E-mail:

Acknowledgments

A.F. is chairing a Sub-Committee on Organ-Specific Autoantibodies of the IUIS Committee on Quality Assessment and Standardization (www.iuisonline.org) and received an unconditioned support from IUIS. We wish to thank Jose Ramón Bilbao, Åsa Hallgren, Hege Hoff Skavøy, Kai Kisand, Belinda Lind, Dongmei Miao, Maire Pihlap, Bernard Rees-Smith, Koit Reimand, and Ingrid Wigheden for valuable discussion and technical help.

Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

Financial support: The study was supported by EU FP7 (grant number 201167), Euradrenal, and in part by NIH grant DK32083.

Disclosure statement: RSR Ltd is a manufacturer of medical diagnostics including kits for 21OH autoantibodies.

Employment or leadership: None declared.

Honorarium: None declared.

Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

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Supplemental Material:

The online version of this article (DOI: 10.1515/cclm-2014-1106) offers supplementary material, available to authorized users.

Received: 2014-11-11
Accepted: 2015-2-11
Published Online: 2015-3-26
Published in Print: 2015-10-1

©2015 by De Gruyter

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https://doi.org/10.1515/cclm-2014-1106
Keywords for this article
Addison’s disease; adrenal antibodies; autoimmunity; diagnosis; RIA; standardization

Articles in the same Issue

  1. Frontmatter
  2. Editorials
  3. Laboratory medicine does matter in science (and medicine)… yet many seem to ignore it
  4. The standardization of the urine albumin assays: no longer deferrable
  5. Reviews
  6. The role of telomeres and vitamin D in cellular aging and age-related diseases
  7. Atypical hemolytic uremic syndrome: from diagnosis to treatment
  8. Clinical relevance and contemporary methods for counting blood cells in body fluids suspected of inflammatory disease
  9. EFLM Opinion Paper
  10. How to assess the quality of your analytical method?
  11. Genetics and Molecular Diagnostics
  12. Validation of CFTR intronic variants identified during cystic fibrosis population screening by a minigene splicing assay
  13. General Clinical Chemistry and Laboratory Medicine
  14. Uncertainty in measurement for 43 biochemistry, immunoassay, and hemostasis routine analytes evaluated by a method using only external quality assessment data
  15. A study examining the bias of albumin and albumin/creatinine ratio measurements in urine
  16. National survey on appropriateness of clinical biochemistry reporting in China
  17. Potentiometric measurement of urinary iodine concentration in patients with thyroid diseases with and without previous exposure to non-radioactive iodine
  18. Determination of 21-hydroxylase autoantibodies: inter-laboratory concordance in the Euradrenal International Serum Exchange Program
  19. Value of a commercial kit for detecting anti-C1q autoantibodies and correlation with immunological and clinical activity of lupus nephritis
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  21. Measurement of the inflammatory response in the early postoperative period after hip and knee arthroplasty
  22. Whole blood thromboelastometry profiles in women with preeclampsia
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  25. Reference ranges of serum bile acids in children and adolescents
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  29. Head-to-head comparison of 10 natriuretic peptide assays
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