Effect of dexamethasone administration on serum thyroid hormone concentrations in clinically normal horses.
Abstract: The effect that 5 consecutive days of treatment with dexamethasone (0.04 mg/kg of body weight, IM, q 24 h) would have on baseline concentrations of triiodothyronine (T3), thyroxine (T4), reverse T3 (rT3), free T3 (FT3), and free T4 (FT4), and on response to thyroid-stimulating hormone (TSH) administration was determined in 12 clinically normal horses. Results of TSH response tests indicated that the horses could be placed into 2 groups: in 6 horses (group A), T4 concentration after administration of TSH was more than twice the baseline concentration; in the other 6 horses (group B), T4 concentration 6 hours after administration of TSH was less than twice the baseline concentration. Baseline serum concentrations of T3, T4, rT3, FT3, and FT4 were not significantly different between group-A and group-B horses. In both groups of horses, serum T3, T4, rT3, and FT4 concentrations were significantly increased 6 hours following TSH administration, compared with baseline concentrations. Treatment with dexamethasone resulted in significant (P < 0.05) increases in baseline concentrations of rT3 and FT3 in group-A horses and baseline concentrations of rT3 in group-B horses. The response to TSH administration following dexamethasone treatment appeared to be blunted with significant (P < 0.05) increases only in T3, T4, and FT4 concentrations in group-A horses and FT4 concentration in group-B horses. The magnitude of change in serum FT3 concentration in response to TSH administration was significantly less (P = 0.05) following dexamethasone treatment, compared with magnitude of change prior to dexamethasone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1995-01-01 PubMed ID: 7744665
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- Journal Article
Summary
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The research article explores the impact of dexamethasone treatment on the concentration of thyroid hormones in healthy horses. The findings indicate that the drug causes an increase in some hormone levels and blunts the response to thyroid-stimulating hormone.
Objective and Methodology
- The primary aim of this study was to investigate the effect of a steroid medication, dexamethasone, given over five consecutive days, on the baseline concentrations of various thyroid hormones in clinically healthy horses.
- The hormones studied were triiodothyronine (T3), thyroxine (T4), reverse T3 (rT3), free T3 (FT3), and free T4 (FT4). Furthermore, the researchers evaluated the response to the administration of thyroid-stimulating hormone (TSH).
- The study involved a total of 12 horses, which, based on their TSH response, could be categorized into two groups: group A and group B. Group A included horses where T4 concentration increased more than twice the baseline level after TSH administration, and group B constituted horses where the increase was less than twice.
Results and Findings
- An interesting finding of the study was that there were no significant differences in the baseline concentrations of T3, T4, rT3, FT3, and FT4 between group A and group B horses.
- Despite these similarities, implementation of dexamethasone treatment led to noteworthy increases in rT3 and FT3 levels in group A and just rT3 levels in group B horses.
- It was also observed that the horses’ response to TSH administration after having been treated with dexamethasone was blunted. This was demonstrated by a significant increase only in T3, T4, and FT4 levels in group A horses and FT4 levels in group B horses.
- Finally, the change in FT3 concentration due to TSH administration was significantly less following dexamethasone treatment compared to prior treatment. This suggests a potential effect of dexamethasone on the thyroid hormone regulation mechanism in horses.
Conclusions
- The study thus establishes a connection between dexamethasone treatment and thyroid hormone concentration changes. The possible implications of this effect are significant, suggesting a reconsideration of dexamethasone usage in equine medicine due to its potential impact on thyroid function.
Cite This Article
APA
Messer NT, Ganjam VK, Nachreiner RF, Krause GF.
(1995).
Effect of dexamethasone administration on serum thyroid hormone concentrations in clinically normal horses.
J Am Vet Med Assoc, 206(1), 63-66.
Publication
Researcher Affiliations
- Department of Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia 65211.
MeSH Terms
- Animals
- Dexamethasone / pharmacology
- Female
- Horses / blood
- Male
- Reference Values
- Thyroid Gland / drug effects
- Thyroid Gland / metabolism
- Thyrotropin
- Thyroxine / blood
- Triiodothyronine / blood
Citations
This article has been cited 1 times.- 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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