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Measurement of free thyroxine concentration in horses by equilibrium dialysis.
Abstract: The purpose of the study reported here was to validate measurement of free thyroxine (fT4) concentration in equine serum by equilibrium dialysis (fT4D), and to compare values with fT4 concentration measured directly and with total T4 (TT4) concentration. The fT4D, fT4, and TT4 concentrations were measured over a range of values in euthyroid horses and horses made hypothyroid by administration of propylthiouracil (PTU). Concentrations of fT4D (<1.8-83 pmol/L) were consistently higher than those of fT4 (<1-40 pmol/L). There was a significant (P < .001) regression of fT4D on fT4 in 503 samples from normal horses (y = 2.086x - 0.430). In baseline samples from 71 healthy euthyroid horses, fT4 concentration ranged from 6-21 pmol/L (median, 11 pmol/L; 95% confidence interval [CI]10.5-11.8 pmol/L), and fT4D concentration ranged from 7-47 pmol/L (median, 22 pmol/L; 95% CI 20.9-25.1 pmol/L). Free T4D, fT4, and TT4 concentrations were also measured in 34 ill horses. Horses consuming PTU and ill horses had significantly (P < .05) lower serum concentration of TT4, fT4, and fT4D than did clinically normal, healthy horses. If serum samples from ill horses were further subdivided into samples from horses that lived and samples from horses that died, fT4D concentration was not significantly different in ill horses that lived, compared with that in healthy horses, whereas fT4 concentration was still significantly decreased in ill horses that died (P < 0.001). We conclude that measurement of fT4 concentration by equilibrium dialysis is a valid technique in the horse, and its use may provide improved ability to distinguish nonthyroidal illness syndrome from hypothyroidism in that species.
Publication Date: 2006-04-06 PubMed ID: 16594596DOI: 10.1892/0891-6640(2006)20[371:moftci]2.0.co;2Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
- Animal Health
- Animal Studies
- Clinical Findings
- Clinical Pathology
- Clinical Study
- Comparative Study
- Diagnosis
- Diagnostic Technique
- Disease Diagnosis
- Disease Etiology
- Disease Management
- Disease Treatment
- Equine Diseases
- Equine Health
- Horses
- Laboratory Methods
- Physiology
- Regression Analysis
- Thyroid Hormones
- Veterinary Medicine
- Veterinary Research
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.
This research article explores and validates the measurement of free thyroxine (fT4) concentration in horse serum using equilibrium dialysis (fT4D) and compares these results to the value of fT4 concentration measured directly and total thyroxine concentration.
Research Methodology and Measurements
- The study aimed to validate the technique of equilibrium dialysis for measuring the concentration of free thyroxine (fT4) in the serum of equine subjects. It also compared these measured values to direct measurement of fT4 and total T4 (TT4) concentration.
- The fT4D, fT4, and TT4 concentrations were assessed in both normal, healthy horses (euthyroid horses) and in horses that were made hypothyroid through administration of propylthiouracil (PTU).
- Concentrations of fT4D were consistently recorded as higher than those of fT4 across an array of values.
Results and Findings
- The researchers found a statistically significant regression of fT4D on fT4 in samples taken from normal horses.
- In samples collected from 71 healthy horses (baseline samples), the measured fT4 concentration fluctuated between 6-21 pmol/L, while the fT4D concentration had a broader range from 7-47 pmol/L.
- Measurements were also conducted on 34 ill horses, who alongside the horses consuming PTU, displayed significantly lower serum levels of TT4, fT4, and fT4D, as compared to healthy horses.
- If the data from ill horses was further subdivided into those that survived and those that didn’t, the fT4D concentration was discovered not to be significantly different in surviving ill horses compared to healthy ones. Nevertheless, fT4 concentration was still considerably lowered in ill horses that did not survive.
Conclusion and Implication
- The research concluded that measuring fT4 concentration in horse serum using equilibrium dialysis is indeed a valid and reliable technique.
- The use of this technique may lead to improved diagnostic precision in distinguishing between non-thyroidal illness and hypothyroidism in horses.
Cite This Article
APA
Breuhaus BA, Refsal KR, Beyerlein SL.
(2006).
Measurement of free thyroxine concentration in horses by equilibrium dialysis.
J Vet Intern Med, 20(2), 371-376.
https://doi.org/10.1892/0891-6640(2006)20[371:moftci]2.0.co;2 Publication
Researcher Affiliations
- North Carolina State University, College of Veterinary Medicine, Raleigh 27606, USA. betta_breuhaus@ncsu.edu
MeSH Terms
- Animals
- Dialysis / methods
- Dialysis / veterinary
- Female
- Horse Diseases / blood
- Horse Diseases / diagnosis
- Horses / blood
- Hypothyroidism / blood
- Hypothyroidism / diagnosis
- Hypothyroidism / veterinary
- Male
- Reference Values
- Thyroxine / blood
Citations
This article has been cited 4 times.- Tangyuenyong S, Sato F, Nambo Y, Murase H, Endo Y, Tanaka T, Nagaoka K, Watanabe G. Comparison of physical body growth and metabolic and reproductive endocrine functions between north and south climates of Japan in trained Thoroughbred yearling horses. J Equine Sci 2017;28(3):77-86.
- Tangyuenyong S, Nambo Y, Nagaoka K, Tanaka T, Watanabe G. Sensitive radioimmunoassay of total thyroxine (T4) in horses using a simple extraction method. J Vet Med Sci 2017 Jul 28;79(7):1294-1300.
- Breuhaus BA. Thyroid function and dysfunction in term and premature equine neonates. J Vet Intern Med 2014 Jul-Aug;28(4):1301-9.
- Hilderbran AC, Breuhaus BA, Refsal KR. Nonthyroidal illness syndrome in adult horses. J Vet Intern Med 2014 Mar-Apr;28(2):609-17.
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