Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats
Abstract Background No gold standard assay for serum total thyroxine (TT4) concentration in small animals exists. The Microgenics DRI TT4 (MTT4) assay is used by most reference laboratories. Hypothesis/Objectives IDEXX Catalyst Total T4 (CTT4) and Immulite 2000 TT4 (ITT4) results will agree with MTT...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2020-03-01
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| Series: | Journal of Veterinary Internal Medicine |
| Subjects: | |
| Online Access: | https://doi.org/10.1111/jvim.15703 |
| _version_ | 1819210391491706880 |
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| author | Ewan D. S. Wolff Graham Bilbrough George Moore Lynn Guptill J. Catharine Scott‐Moncrieff |
| author_facet | Ewan D. S. Wolff Graham Bilbrough George Moore Lynn Guptill J. Catharine Scott‐Moncrieff |
| author_sort | Ewan D. S. Wolff |
| collection | DOAJ |
| description | Abstract Background No gold standard assay for serum total thyroxine (TT4) concentration in small animals exists. The Microgenics DRI TT4 (MTT4) assay is used by most reference laboratories. Hypothesis/Objectives IDEXX Catalyst Total T4 (CTT4) and Immulite 2000 TT4 (ITT4) results will agree with MTT4 results. Animals Residual small animal sera were randomized before reanalysis (dogs, CTT4 versus MTT4: n = 176, ITT4 versus MTT4: n = 74; cats, CTT4 versus MTT4: n = 319, ITT4 versus MTT4: n = 79). Methods Validation and method comparison study. Serum TT4 concentration was measured on all analyzers. Pairwise Pearson correlation, cumulative sum linearity test, regression, and Bland‐Altman method were performed. Results CTT4 versus MTT4 in dogs: constant bias (y‐intercept) was 0.10 μg/dL (95% confidence interval [CI], 0.05‐0.15), proportional bias (slope) was 0.86 μg/dL (95% CI, 0.83‐0.89); in cats, constant bias was 0.13 μg/dL (95% CI, 0.08‐0.20) and proportional bias was 1.01 μg/dL (95% CI, 0.98‐1.03), but the test for linearity failed. Bland‐Altman plots identified increasing disagreement with increasing serum TT4 concentrations. ITT4 versus MTT4 in dogs, constant bias was 0.14 μg/dL (95% CI, 0.04‐0.22) and 0.22 μg/dL (95% CI, 0.09‐0.33) for cats; proportional bias was 0.76 (95% CI, 0.72‐0.80) for dogs and 0.71 (95% CI, 0.69‐0.74) for cats. Conclusions and Clinical Importance Differences in CTT4 and MTT4 results affect interpretation at higher serum TT4 concentrations. The ITT4 proportional bias will underestimate serum TT4 concentrations in dogs and cats, compared to MTT4. Serial TT4 measurements should be done using the same assay. |
| first_indexed | 2024-12-23T06:10:26Z |
| format | Article |
| id | doaj.art-a86a1770c45945cba0e04a3a7163d4ec |
| institution | Directory Open Access Journal |
| issn | 0891-6640 1939-1676 |
| language | English |
| last_indexed | 2024-12-23T06:10:26Z |
| publishDate | 2020-03-01 |
| publisher | Wiley |
| record_format | Article |
| series | Journal of Veterinary Internal Medicine |
| spelling | doaj.art-a86a1770c45945cba0e04a3a7163d4ec2022-12-21T17:57:28ZengWileyJournal of Veterinary Internal Medicine0891-66401939-16762020-03-0134260761510.1111/jvim.15703Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and catsEwan D. S. Wolff0Graham Bilbrough1George Moore2Lynn Guptill3J. Catharine Scott‐Moncrieff4Purdue University College of Veterinary Medicine West Lafayette IndianaIDEXX Laboratories Inc Westbrook MainePurdue University College of Veterinary Medicine West Lafayette IndianaPurdue University College of Veterinary Medicine West Lafayette IndianaPurdue University College of Veterinary Medicine West Lafayette IndianaAbstract Background No gold standard assay for serum total thyroxine (TT4) concentration in small animals exists. The Microgenics DRI TT4 (MTT4) assay is used by most reference laboratories. Hypothesis/Objectives IDEXX Catalyst Total T4 (CTT4) and Immulite 2000 TT4 (ITT4) results will agree with MTT4 results. Animals Residual small animal sera were randomized before reanalysis (dogs, CTT4 versus MTT4: n = 176, ITT4 versus MTT4: n = 74; cats, CTT4 versus MTT4: n = 319, ITT4 versus MTT4: n = 79). Methods Validation and method comparison study. Serum TT4 concentration was measured on all analyzers. Pairwise Pearson correlation, cumulative sum linearity test, regression, and Bland‐Altman method were performed. Results CTT4 versus MTT4 in dogs: constant bias (y‐intercept) was 0.10 μg/dL (95% confidence interval [CI], 0.05‐0.15), proportional bias (slope) was 0.86 μg/dL (95% CI, 0.83‐0.89); in cats, constant bias was 0.13 μg/dL (95% CI, 0.08‐0.20) and proportional bias was 1.01 μg/dL (95% CI, 0.98‐1.03), but the test for linearity failed. Bland‐Altman plots identified increasing disagreement with increasing serum TT4 concentrations. ITT4 versus MTT4 in dogs, constant bias was 0.14 μg/dL (95% CI, 0.04‐0.22) and 0.22 μg/dL (95% CI, 0.09‐0.33) for cats; proportional bias was 0.76 (95% CI, 0.72‐0.80) for dogs and 0.71 (95% CI, 0.69‐0.74) for cats. Conclusions and Clinical Importance Differences in CTT4 and MTT4 results affect interpretation at higher serum TT4 concentrations. The ITT4 proportional bias will underestimate serum TT4 concentrations in dogs and cats, compared to MTT4. Serial TT4 measurements should be done using the same assay.https://doi.org/10.1111/jvim.15703chemiluminescenceenzyme immunoassayhyperthyroidismhypothyroidism |
| spellingShingle | Ewan D. S. Wolff Graham Bilbrough George Moore Lynn Guptill J. Catharine Scott‐Moncrieff Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats Journal of Veterinary Internal Medicine chemiluminescence enzyme immunoassay hyperthyroidism hypothyroidism |
| title | Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats |
| title_full | Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats |
| title_fullStr | Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats |
| title_full_unstemmed | Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats |
| title_short | Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats |
| title_sort | comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats |
| topic | chemiluminescence enzyme immunoassay hyperthyroidism hypothyroidism |
| url | https://doi.org/10.1111/jvim.15703 |
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