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Increased IgA in a subject with positive anti-thyroid autoantibodies – a case report

Slavica Dodig orcid.org/0000-0002-3419-5171 ; Department of Clinical Laboratory Diagnosis, Srebrnjak Children's Hospital, Zagreb, Croatia
Renata Zrinski Topić orcid.org/0000-0002-3740-7854 ; Department of Clinical Laboratory Diagnosis, Srebrnjak Children's Hospital, Zagreb, Croatia
Jadranka Demirović ; Clinical Laboratory, University Hospital for Tumors, Zagreb, Croatia
Jadranka Živčić ; Department of Clinical Laboratory Diagnosis, Srebrnjak Children's Hospital, Zagreb, Croatia

Abstract

Introduction: Increased concentrations of antithyroid autoantibodies are found in inflammatory diseases as well as in thyroid autoimmune disorders. The aim of this report is to present increased IgA concentrations in a female patient with positive anti-thyroid autoantibodies. Results throughout 13 months of follow-up are presented.
Materials and methods: The levels of thyroid hormones and antibodies in the serum samples were measured using microparticle enzyme-immunoas-say. IgA was determined by two immunochemical methods, immuno-turbi-dimetric method and radial immunodiffusion, respectively.
Results: Initial thyroid function tests showed normal values of T3, T4 and thyroid stimulating hormone (TSH), and increased values of thyroid peroxi-dase autoantibodies (anti-TPO), anti-thyroglobulin (anti-Tg) autoantibodies and IgA. The patient underwent treatment with single daily dose of levot-hyroxine. The elevated initial levels of anti-TPO stabilized with the administration of levothyroxine, while anti-Tg remained increased. IgA determined by immuno-turbidimetric method was significantly increased during the follow-up period. Repeated determination of IgA by radial immunodiffusion revealed lower IgA concentrations.
Conclusion: Possible false increased IgA values could be a result of both, interferences of goat anti-IgA antibodies from reagents, and cross-reactivity with endogenous anti-Tg autoantibodies in serum, respectively. Further investigations are needed to ascertain the cause of increased IgA values in patient with positive anti-thyroid autoantibodies.

Keywords

IgA; immunoassay; interferences; thyroid disease; autoantibody

Hrčak ID:

47855

URI

https://hrcak.srce.hr/47855

Publication date:

1.2.2010.

Article data in other languages: croatian

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