Not the usual suspect: Polymeric IgA paraprotein causes false positive results in kinetic interaction of microparticles in solution (KIMS) immunoassays.

David J Kemble, Simon Lamothe, Lynne Uhl

Clinical biochemistry 2021 Jun

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Immunoassays are commonly used by the clinical laboratory, but paraproteins can occasionally produce erroneous results. In this study, we investigated the cause of apparent false positive results for multiple Kinetic Interaction of Microparticles in Solution (KIMS) immunoassays. Patient controls and samples containing the interference were analyzed using automated chemistry platforms, gel electrophoresis, immunofixation, affinity chromatography, and size exclusion chromatography. Our results show that IgA paraprotein caused false positive results for the KIMS measurement of three therapeutic drugs. To our knowledge, this is the first report of IgA paraprotein-causing immunoassay interference. The clinical implications of this interference are discussed. Copyright © 2021 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Citation

David J Kemble, Simon Lamothe, Lynne Uhl. Not the usual suspect: Polymeric IgA paraprotein causes false positive results in kinetic interaction of microparticles in solution (KIMS) immunoassays. Clinical biochemistry. 2021 Jun;92:82-85