Effect of thyrotropin-releasing hormone stimulation testing on the oral sugar test in horses when performed as a combined protocol.
Abstract: The use of parallel dynamic tests to identify insulin dysregulation (ID) and pituitary pars intermedia dysfunction (PPID) in horses could have better diagnostic utility than measuring baseline hormone concentrations, if the tests do not alter diagnostic interpretation of one another. Objective: Performing a thyrotropin-releasing hormone (TRH) stimulation test before an oral sugar test (OST) would not affect results of OST. Methods: Twenty-six healthy university-owned horses. Methods: A prospective randomized placebo-controlled, crossover design was used to evaluate 3 OST protocols: OST alone, TRH followed by OST (TRH + OST), and placebo followed by OST (placebo + OST). Agreement for plasma insulin concentrations and diagnostic interpretation were assessed with Bland-Altman and logistic regression analyses, respectively. Results: Bland-Altman analysis of TRH + OST versus OST alone showed good agreement between testing protocols, with bias ± SD for insulin concentrations at baseline 0.4 ± 4.7 μIU/mL (95% limits of agreement [LOA], -8.8 to 9.7), 60 minute -0.5 ± 22.6 μIU/mL (95% LOA, -44.7 to 43.8), and 90 minute 1.9 ± 20.6 μIU/mL (95% LOA, -38.5 to 42.4) after OST, similar to placebo + OST versus OST alone. Diagnostic interpretation (positive/negative) was not different between protocols (TRH + OST versus OST alone [P = .78], placebo + OST versus OST alone [P = .77], or TRH + OST versus placebo + OST [P = .57]). Conclusions: Concurrent testing for PPID and ID with a TRH stimulation test before an OST is an acceptable diagnostic tool for investigation of endocrinopathies in horses and allows accurate testing to be performed efficiently in 1 visit.
© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
Publication Date: 2019-08-20 PubMed ID: 31432575PubMed Central: PMC6766522DOI: 10.1111/jvim.15601Google 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
Summary
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The research aimed to assess the impact of performing a thyrotropin-releasing hormone (TRH) stimulation test prior to an oral sugar test (OST) on identifying insulin dysregulation (ID) and pituitary pars intermedia dysfunction (PPID) in horses. Findings suggested that both tests could be conducted effectively together to identify these disorders without interference in the results.
Methodology
- The research used a prospective randomized placebo-controlled, crossover design.
- Twenty-six healthy university-owned horses were involved in the study.
- Three OST protocols were evaluated: OST alone, TRH followed by OST (TRH + OST), and a placebo followed by OST (placebo + OST).
- The agreement for plasma insulin concentrations and diagnostic interpretation was assessed using Bland-Altman and logistic regression analyses.
Results
- The Bland-Altman analysis comparing TRH + OST and OST alone showed good agreement, indicating similar insulin concentrations between the two testing procedures.
- Comparisons of TRH + OST with OST alone were nearly identical to that of placebo + OST with OST alone.
- The diagnostic interpretations (positive or negative results) didn’t significantly differ across the different protocols.
- Results demonstrated strong concurrence across all testing protocols, suggesting the co-administration of TRH and OST tests doesn’t affect the reliability of results.
Conclusions
- The TRH stimulation test can be performed before an OST without altering the test results, demonstrating appropriate diagnostic tools for testing hormone dysregulation in horses.
- Coupled testing allows accurate and efficient diagnosis of endocrinopathies in horses in a single visit, enhancing practicality and convenience for veterinarians and horse owners.
Cite This Article
APA
Hodge E, Kowalski A, Torcivia C, Lindborg S, Stefanovski D, Hart K, Frank N, van Eps A.
(2019).
Effect of thyrotropin-releasing hormone stimulation testing on the oral sugar test in horses when performed as a combined protocol.
J Vet Intern Med, 33(5), 2272-2279.
https://doi.org/10.1111/jvim.15601 Publication
Researcher Affiliations
- School of Veterinary Medicine, University of Pennsylvania, Clinical Studies-New Bolton Center, Kennett Square, Chester, Pennsylvania.
- School of Veterinary Medicine, University of Pennsylvania, Clinical Studies-New Bolton Center, Kennett Square, Chester, Pennsylvania.
- School of Veterinary Medicine, University of Pennsylvania, Clinical Studies-New Bolton Center, Kennett Square, Chester, Pennsylvania.
- School of Veterinary Medicine, University of Pennsylvania, Clinical Studies-New Bolton Center, Kennett Square, Chester, Pennsylvania.
- School of Veterinary Medicine, University of Pennsylvania, Clinical Studies-New Bolton Center, Kennett Square, Chester, Pennsylvania.
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia.
- Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts.
- School of Veterinary Medicine, University of Pennsylvania, Clinical Studies-New Bolton Center, Kennett Square, Chester, Pennsylvania.
MeSH Terms
- Adrenocorticotropic Hormone / blood
- Animals
- Cross-Over Studies
- Female
- Glucose Tolerance Test / veterinary
- Horses / blood
- Horses / metabolism
- Insulin / blood
- Male
- Pituitary Gland, Intermediate / physiology
- Prospective Studies
- Random Allocation
- Thyrotropin-Releasing Hormone / pharmacology
Grant Funding
- Raymond Firestone Trust Research Grant
- Tamworth Research Fund
Conflict of Interest Statement
Authors declare no conflict of interest.
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Citations
This article has been cited 2 times.- Stefanovski D, Robinson MA, Van Eps A. Effect of a GLP-1 mimetic on the insulin response to oral sugar testing in horses.. BMC Vet Res 2022 Jul 29;18(1):294.
- Thane K, Uricchio C, Frank N. Effect of early or late blood sampling on thyrotropin releasing hormone stimulation test results in horses.. J Vet Intern Med 2022 Mar;36(2):770-777.