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Veterinary sciences2026; 13(7); 690; doi: 10.3390/vetsci13070690

Assessment of Thyroid Hormones Using the Immulite 2000xpi Analyzer in Healthy Donkeys.

Abstract: The Immulite 2000xpi, a chemiluminescent immunoassay (CLIA)-based analyzer, is currently recommended for measuring thyroid hormones (TH) concentrations in equids. However, scarce data are available on TH measurements in donkeys using this technique. Similarly, the effects of factors such as age and gender on TH concentrations have not been assessed with this analyzer. Serum free and total T4 and T3 concentrations were measured in 40 healthy donkeys (6.1 ± 0.8 years old; 8 intact jacks and 32 jennies) and 41 horses (10.7 ± 0.5 years old; 15 stallions and 26 geldings) using the Immulite 2000xpi. A Mann-Whitney test was used to compare two groups, and a Kruskal-Wallis test followed by Dunn's post hoc test was used for comparisons among more than two groups. This analyzer had lower intra-assay variability and fewer measurements under the detection limit for tT4 and fT4 than for tT3 and fT3 determinations. The canine TSH kit for thyroid-stimulating hormone (TSH) showed high imprecision. Donkeys had higher serum TH concentrations than horses. No differences were observed among gender or age groups. This is the first study to report TH concentrations in donkeys using a CLIA-based analyzer and to evaluate the effects of several factors on TH concentrations. The canine TSH kit is not valid for measuring TSH in equids.
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Publication Date: 2026-07-15 PubMed ID: 42514700PubMed Central: PMC13419001DOI: 10.3390/vetsci13070690Google Scholar: Lookup
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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.

Overview

  • This study evaluated thyroid hormone levels in healthy donkeys using the Immulite 2000xpi, a chemiluminescent immunoassay analyzer commonly used for equids.
  • The research compared thyroid hormone measurements in donkeys and horses and examined the influence of age and gender on these hormone levels.

Background and Purpose

  • The Immulite 2000xpi analyzer, based on chemiluminescent immunoassay (CLIA) technology, is a recommended tool for measuring thyroid hormones in horses and other equids.
  • Despite its use in equine species, there is limited information on the measurement of thyroid hormones in donkeys specifically using this analyzer.
  • It was unclear how factors such as age and gender might affect thyroid hormone concentrations in donkeys when assessed with this technology.
  • The study aimed to fill these knowledge gaps by assessing free and total thyroid hormone levels, and also tested the usefulness of a canine thyroid-stimulating hormone (TSH) kit for equids.

Methodology

  • Subjects: 40 healthy donkeys (average age 6.1 ± 0.8 years; 8 intact males called jacks and 32 females called jennies) and 41 horses (average age 10.7 ± 0.5 years; 15 stallions and 26 geldings).
  • Thyroid hormones measured included free T4 (fT4), total T4 (tT4), free T3 (fT3), and total T3 (tT3).
  • The Immulite 2000xpi analyzer was used for hormone quantification.
  • Statistical analysis involved the Mann-Whitney test for two-group comparisons and Kruskal-Wallis with Dunn’s post hoc test for multiple groups, ensuring robust evaluation of differences based on species, gender, and age.
  • The canine TSH kit was also tested for measuring TSH levels in these equids, focusing on performance and precision metrics.

Key Findings

  • The analyzer showed lower variability and fewer measurements below detection limits for total and free T4 compared to T3 measurements, indicating better reliability in measuring T4 hormones.
  • Measurements of thyroid-stimulating hormone (TSH) using the canine TSH kit were highly imprecise, suggesting this kit is unsuitable for equid TSH assessment.
  • Donkeys had significantly higher serum concentrations of thyroid hormones (both T3 and T4) than horses, indicating species differences in baseline thyroid hormone levels.
  • No significant differences in thyroid hormone concentrations were observed between genders (male vs. female) or across different age groups in either species.

Conclusions and Implications

  • This research is the first to provide reference data on thyroid hormone concentrations in donkeys using a CLIA-based Immulite 2000xpi analyzer.
  • The findings highlight species-specific differences in thyroid hormone levels, which are critical for veterinarians and researchers when interpreting thyroid function tests in donkeys versus horses.
  • Age and gender do not appear to significantly influence thyroid hormone concentrations in healthy donkeys or horses, simplifying interpretation of results across demographic groups.
  • The canine TSH immunoassay kit is not appropriate for equid TSH measurement, signaling a need for species-specific TSH testing tools or development of validated equine/donkey-specific kits.
  • Overall, the Immulite 2000xpi analyzer is a useful tool for measuring T4 and T3 thyroid hormones in donkeys, but caution is necessary when selecting TSH assays.

Cite This Article

APA
Davias C, Perez-Ecija A, Ruiz-Lastra D, Heras AL, Toribio R, Mendoza FJ. (2026). Assessment of Thyroid Hormones Using the Immulite 2000xpi Analyzer in Healthy Donkeys. Vet Sci, 13(7), 690. https://doi.org/10.3390/vetsci13070690

Publication

Veterinary sciences
ISSN: 2306-7381
NlmUniqueID: 101680127
Country: Switzerland
Language: English
Volume: 13
Issue: 7
PII: 690

Researcher Affiliations

Davias, Carmen
  • Department of Animal Medicine and Surgery, University of Cordoba, 14014 Cordoba, Spain.
Perez-Ecija, Alejandro
  • Department of Animal Medicine and Surgery, University of Cordoba, 14014 Cordoba, Spain.
Ruiz-Lastra, Daniela
  • Department of Animal Medicine and Surgery, University of Cordoba, 14014 Cordoba, Spain.
Heras, Adelaida De Las
  • Department of Animal Medicine and Surgery, University of Cordoba, 14014 Cordoba, Spain.
Toribio, Ramiro
  • Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
Mendoza, Francisco J
  • Department of Animal Medicine and Surgery, University of Cordoba, 14014 Cordoba, Spain.

Grant Funding

  • AGR277 / University of Córdoba

Conflict of Interest Statement

The authors declare no conflicts of interest.

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