Evaluation of a Chemiluminescent Immunoassay for Measurement of Equine Insulin



Carslake, HB ORCID: 0000-0003-1288-1768, Pinchbeck, GL ORCID: 0000-0002-5671-8623 and McGowan, CM ORCID: 0000-0002-1946-9584
(2017) Evaluation of a Chemiluminescent Immunoassay for Measurement of Equine Insulin. JOURNAL OF VETERINARY INTERNAL MEDICINE, 31 (2). pp. 568-574.

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Abstract

<h4>Background</h4>Many diagnostic tests for insulin dysregulation use reference intervals established with an insulin radioimmunoassay (RIA) that is no longer available. A chemiluminescent immunoassay (CLIA) is commonly used for the measurement of serum insulin concentration in clinical practice but requires further validation, especially at clinically relevant reference intervals.<h4>Objectives</h4>To evaluate the CLIA for measurement of equine insulin and compare it to the previously validated, but now unavailable RIA.<h4>Samples</h4>Equine serum samples (n = 78) from clinical and experimental studies.<h4>Methods</h4>In this experimental study, performance of the CLIA was evaluated using standard variables, including comparison with the RIA. Continuous and binary outcomes were analyzed.<h4>Results</h4>The CLIA showed good intra-assay (coefficient of variation [CV], 1.8-2.4%) and interassay (CV, 3-7.1%) precision. Acceptable recovery on dilution (100 ± 10%) was achieved only at dilutions <1:1. Recovery on addition was acceptable. Comparison of the CLIA and RIA showed strong positive correlation (r = 0.91-0.98), with fixed and proportional bias. At 3 diagnostic cutoffs, sensitivity of CLIA compared with RIA ranged from 67 to 100% and specificity from 96 to 100%.<h4>Conclusions and clinical importance</h4>The CLIA is a highly repeatable assay which is suitable for within- and between-horse comparisons. Dilution of high concentration samples should be performed with charcoal-stripped serum (CSS) and at the lowest dilution factor possible. At concentrations commonly used for diagnosis of insulin dysregulation (≤100 μIU/mL), results from the CLIA tend to be lower than from the RIA and should be interpreted accordingly. Further standardization of equine insulin assays is required.

Item Type: Article
Uncontrolled Keywords: ELISA, Horse, Laminitis, Metabolic
Depositing User: Symplectic Admin
Date Deposited: 10 Feb 2017 10:42
Last Modified: 19 Jan 2023 07:19
DOI: 10.1111/jvim.14657
Open Access URL: http://onlinelibrary.wiley.com/doi/10.1111/jvim.14...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3005698