Correlation of two nonradioactive immunoassays to a radioimmunoassay technique for thyroxine measurement in equine serum.
Abstract: The purpose of this study was to compare 2 different nonradioactive assay methods with a conventional radioimmunoassay (RIA) measuring the concentration of serum thyroxine (T4) in horses. Serum was obtained from 85 adult standardbred horses. The T4 concentration of each sample was analyzed by RIA, chemiluminescent enzyme immunoassay (CEI), and homogeneous enzyme immunoassay (HEI). The correlation between the HEI method and RIA method was significantly greater (r = 0.89) than the correlation between the CEI and the reference method (r = 0.53). In addition, the precision of the HEI method was significantly greater than the CEI method; within-run percentage coefficients of variation were 4.5% and 15.9%, respectively, at mean T4 concentrations of 19-20 nmol/liter. On the basis of these findings, the HEI method was evaluated further. Both between-run precision and linearity were deemed adequate upon dilution by the HEI method. In addition, recovery of L-thyroxine added to equine serum was linear over 6 concentrations tested and averaged 79.6% with a manufacturer recommended data correction factor. An in-house correction factor was calculated by linear regression analysis of the RIA and HEI results from the original equine serum samples. Use of this correction factor improved the average recovery to 94.2% while maintaining excellent linearity (r2 = 0.9978). Although both nonradioactive methods of T4 analysis could likely substitute for the RIA reference method, the HEI method had the highest correlation and precision. The HEI technique also yielded adequately accurate results after correction of the data with an appropriate correction factor. Individually derived in-house correction factors may improve the accuracy of the HEI method to a greater extent than manufacturer suggested correction factors.
Publication Date: 2000-02-26 PubMed ID: 10690776DOI: 10.1177/104063870001200109Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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The research is a analytical comparison of two nonradioactive immunoassay techniques with a conventional radioimmunoassay method for measuring thyroxine levels in horse serum. It revealed that the Homogeneous Enzyme Immunoassay (HEI) method showed higher correlation and precision compared to Chemiluminescent Enzyme Immunoassay (CEI) and hence was identified as a potential substitute for the conventional method.
Research Objective and Methods
- The objective of this research was to compare two nonradioactive testing methods for measuring thyroxine (T4) concentration in horse blood serum, against a conventional radioactive testing method.
- The conventional method used is Radioimmunoassay (RIA), while the two nonradioactive ones are Chemiluminescent Enzyme Immunoassay (CEI) and Homogeneous Enzyme Immunoassay (HEI).
- The researchers collected serum from 85 adult Standardbred horses and analyzed the concentration of T4 in each sample by all three methods.
Comparative Analysis and Findings
- The correlation between the HEI method and the RIA method was significantly higher than the correlation between CEI and RIA.
- The precision of the HEI method was also found to be higher than the CEI method.
- Based on these findings, the HEI method was further evaluated for its between-run precision, linearity upon dilution, and recovery of thyroxine added to equine serum.
Further Evaluation of HEI Method
- The recovery by HEI method of L-thyroxine added to equine serum was linear over 6 concentrations tested and averaged 79.6% with a manufacturer recommended data correction factor.
- An in-house correction factor was calculated and when used, improved the average recovery to 94.2% while maintaining excellent linearity.
Conclusions
- The conclusions drawn from the study underline that despite both nonradioactive methods presenting as likely substitutes for the conventional Radioimmunoassay method, the Homogeneous Enzyme Immunoassay method demonstrated the highest correlation and precision.
- The study also suggested that using individually derived in-house correction factors over manufacturer suggested ones can yield more accurate results from the HEI method.
Cite This Article
APA
Solter PF, Farner S.
(2000).
Correlation of two nonradioactive immunoassays to a radioimmunoassay technique for thyroxine measurement in equine serum.
J Vet Diagn Invest, 12(1), 51-56.
https://doi.org/10.1177/104063870001200109 Publication
Researcher Affiliations
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana 61802, USA.
MeSH Terms
- Animals
- Horses / physiology
- Immunoassay / standards
- Immunoassay / veterinary
- Radioimmunoassay / standards
- Radioimmunoassay / veterinary
- Regression Analysis
- Reproducibility of Results
- Sensitivity and Specificity
- Thyroxine / analysis
Citations
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