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Domestic animal endocrinology2011; 41(2); 81-90; doi: 10.1016/j.domaniend.2011.05.001

Evaluation of commercially available assays for the measurement of equine insulin.

Abstract: Determining circulating equine insulin concentrations is becoming increasingly important in equine clinical practice and research. Most available assays are optimized for human medicine, but there is strong equine cross-reactivity because of the highly conserved nature of insulin. To identify an accurate and reliable assay for equine insulin, 6 commercial immunoassays were evaluated for precision, accuracy, and specificity. Only 1 assay initially reached the requisite standard: Mercodia Equine Insulin Enzyme-linked Immunosorbent assay (ELISA). Plasma matrix interferences were identified when the provided assay buffer was used with the Siemens Count-a-Coat Insulin radioimmunoassay (RIA) but not when charcoal-stripped equine plasma was used as the diluent. This modified RIA and the Mercodia Equine Insulin ELISA were evaluated further by directly examining accuracy by comparing their results for 18 equine plasma samples with values obtained using liquid chromatography and high-resolution/high-accuracy mass spectrometry (LC-MS). Compared with LC-MS measurements, the modified Siemens Insulin RIA rendered a moderate Lin's concordance coefficient (ρ(c)) of 0.41, whereas the Mercodia Equine Insulin ELISA rendered a very poor ρ(c) of 0.06. This suggests that the Siemens Insulin RIA is appropriate to use for routine evaluations when LC-MS is not available.
Copyright © 2011 Elsevier Inc. All rights reserved.
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Publication Date: 2011-05-31 PubMed ID: 21741576DOI: 10.1016/j.domaniend.2011.05.001Google Scholar: Lookup
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  • Comparative Study
  • Evaluation Study
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study assesses commercially available assays for measuring equine insulin levels, concluding that the Siemens Insulin Radioimmunoassay (RIA) fares better than others, but only when modified to account for interference issues.

Objective of the Study

  • The research aimed to identify a reliable and accurate commercial assay for the measurement of equine insulin, given the growing significance of determining circulating equine insulin concentrations in veterinary practice and research.

Analysis of Commercial Immunoassays

  • The study evaluated six commercial immunoassays based on their precision, accuracy, and specificity.
  • Only one of the six tests, the Mercodia Equine Insulin Enzyme-linked Immunosorbent assay (ELISA), met the required standards in the preliminary assessment.

Issues with Siemens Count-a-Coat Insulin RIA

  • Plasma matrix interferences, which can distort the test results, were detected with the Siemens Count-a-Coat Insulin Radioimmunoassay (RIA) when the provided assay buffer was used.
  • However, these interference issues were eliminated when charcoal-stripped equine plasma was used as the diluent.

Comparative Evaluation of Siemens Insulin RIA and Mercodia Equine Insulin ELISA

  • The modified Siemens Insulin RIA and the Mercodia Equine Insulin ELISA were then further compared for accuracy.
  • This was done by comparing the outputs of these tests for 18 equine plasma samples with the values obtained using liquid chromatography and high-resolution/high-accuracy mass spectrometry (LC-MS), which is a well-established method for analyzing biological samples.

Results of the Study

  • Compared with LC-MS measurements, the modified Siemens Insulin RIA showed a moderate Lin’s concordance coefficient (ρ(c)) of 0.41, indicating moderate agreement.
  • The Mercodia Equine Insulin ELISA showed a very poor Lin’s concordance coefficient of 0.06, pointing towards poor agreement with the LC-MS measurements.
  • This indicates that the Siemens Insulin RIA, when used with suitable modifications to account for interference, is better suited for routine evaluations when LC-MS is not available.

Cite This Article

APA
Tinworth KD, Wynn PC, Boston RC, Harris PA, Sillence MN, Thevis M, Thomas A, Noble GK. (2011). Evaluation of commercially available assays for the measurement of equine insulin. Domest Anim Endocrinol, 41(2), 81-90. https://doi.org/10.1016/j.domaniend.2011.05.001

Publication

Domestic animal endocrinology
ISSN: 1879-0054
NlmUniqueID: 8505191
Country: United States
Language: English
Volume: 41
Issue: 2
Pages: 81-90

Researcher Affiliations

Tinworth, K D
  • School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
Wynn, P C
    Boston, R C
      Harris, P A
        Sillence, M N
          Thevis, M
            Thomas, A
              Noble, G K

                MeSH Terms

                • Animals
                • Horses / blood
                • Insulin / blood
                • Radioimmunoassay / veterinary
                • Reproducibility of Results
                • Sensitivity and Specificity

                Citations

                This article has been cited 16 times.
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                12. Dunbar LK, Mielnicki KA, Dembek KA, Toribio RE, Burns TA. Evaluation of Four Diagnostic Tests for Insulin Dysregulation in Adult Light-Breed Horses. J Vet Intern Med 2016 May;30(3):885-91.
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                14. Espinosa-López EM, Ortiz-Guisado B, Diez de Castro E, Durham A, Aguilera-Tejero E, Gómez-Baena G. Quantitative proteomics unveils potential plasma biomarkers and provides insights into the pathophysiological mechanisms underlying equine metabolic syndrome. BMC Vet Res 2025 Jul 2;21(1):425.
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                15. Nolen-Walston RD, Kulp JC, Stefanovski D, van Eps AW. Evaluation of an Automated Fluorescence Enzyme Immunoassay for Quantification of Equine Insulin and Comparison to Five Other Immunoassays. J Vet Intern Med 2025 Mar-Apr;39(2):e70038.
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                16. Embaby A, Balai M, Franssen EJF. Insulin overdose with fatal outcome?: Two forensic cases. Toxicol Rep 2024 Jun;12:542-545.
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