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Home / Equine Research Bank / J Vet Intern Med / Evaluation of combined testing to simultaneously diagnose pi...
Journal of veterinary internal medicine2019; 33(5); 2249-2256; doi: 10.1111/jvim.15617

Evaluation of combined testing to simultaneously diagnose pituitary pars intermedia dysfunction and insulin dysregulation in horses.

Abstract: The thyrotropin-releasing hormone (TRH) stimulation test and the 2-step insulin sensitivity test are commonly used methods to diagnose, respectively, pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID). Objective: To investigate the diagnostic value of combining the TRH stimulation test and the 2-step insulin sensitivity test to diagnose PPID and ID simultaneously. Methods: Twenty-seven adult horses, 10 control horses without PPID or ID, 5 horses with PPID only, 5 horses with ID only, and 7 horses with PPID and ID. Methods: Randomized prospective study. Horses underwent a TRH stimulation test alone, a 2-step insulin sensitivity test alone, and combined testing with simultaneous TRH and insulin injection in the same syringe. Data were compared by 2-way repeated measures analysis of variance and 2 1-sided tests to demonstrate equivalence. Bland-Altman plots were generated to visualize agreement between combined and independent testing. Results: The effect of combined testing on plasma adrenocorticotropic hormone, blood glucose concentration, or percentage decrease in blood glucose concentration was not significantly different from the effect obtained with independent testing. One control horse appeared falsely positive for PPID, 2 PPID-only horses appeared falsely positive for ID, and 1 PPID and ID horse appeared falsely negative for ID when tests were performed simultaneously. Bland-Altman plots supported the agreement between combined and independent testing. Conclusions: Combining the TRH stimulation test and the 2-step insulin sensitivity test appears to be a useful diagnostic tool for equine practitioners in the field, allowing testing of a horse for both PPID and ID simultaneously.
© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
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Publication Date: 2019-09-09 PubMed ID: 31498947PubMed Central: PMC6766519DOI: 10.1111/jvim.15617Google Scholar: Lookup
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  • Journal Article

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.

The research study investigates the effectiveness of combining two existing diagnostic tests (the thyrotropin-releasing hormone (TRH) stimulation test and the 2-step insulin sensitivity test) to concurrently diagnose two horse diseases, pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID).

Objective and Methodology

  • The main objective of this study was to evaluate the diagnostic value of the combined TRH stimulation test and the 2-step insulin sensitivity test in diagnosing both PPID and ID in horses concurrently.
  • The study involved 27 adult horses segregated into four groups: 10 healthy control horses, 5 horses with only PPID, 5 horses with only ID, and 7 horses with both PPID and ID.
  • The methodology used was a randomized prospective study where horses underwent individual TRH stimulation tests, individual 2-step insulin sensitivity tests, and combined testing with simultaneous TRH and insulin injection.
  • The results from these tests were analyzed and compared through specific statistical measures and plotting techniques, such as 2-way repeated measures analysis of variance, 2 1-sided tests for demonstrating equivalence, and Bland-Altman plots.

Results

  • The results did not show a significant difference between the effect of combined testing and independent testing on plasma adrenocorticotropic hormone levels, blood glucose concentration, or the decrease percentage in blood glucose concentration.
  • However, there were cases of false positives and false negatives when the tests were performed simultaneously. One control horse falsely tested positive for PPID; two horses with PPID only appeared falsely positive for ID; and one horse with both PPID and ID seemed falsely negative for ID.
  • Despite these incidents of false results, Bland-Altman plots supported the overall agreement between combined testing and individual testing.

Conclusions

  • The combined TRH stimulation test and the 2-step insulin sensitivity test proved to be a beneficial diagnostic tool for equine practitioners.
  • This combination allows for the simultaneous testing of PPID and ID in horses, optimizing the diagnostic process compared to individually conducting the tests.
  • The authors recommend integrating this combined testing method into regular veterinary practice, despite the highlighted instances of false results.

Cite This Article

APA
Horn R, Bertin FR. (2019). Evaluation of combined testing to simultaneously diagnose pituitary pars intermedia dysfunction and insulin dysregulation in horses. J Vet Intern Med, 33(5), 2249-2256. https://doi.org/10.1111/jvim.15617

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 33
Issue: 5
Pages: 2249-2256

Researcher Affiliations

Horn, Remona
  • School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia.
Bertin, François-René
  • School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia.

MeSH Terms

  • Adrenocorticotropic Hormone / blood
  • Animals
  • Blood Glucose
  • Female
  • Horse Diseases / blood
  • Horse Diseases / diagnosis
  • Horse Diseases / metabolism
  • Horses
  • Insulin Resistance
  • Male
  • Pituitary Diseases / blood
  • Pituitary Diseases / diagnosis
  • Pituitary Diseases / veterinary
  • Pituitary Gland, Intermediate / pathology
  • Prospective Studies
  • Random Allocation
  • Thyrotropin-Releasing Hormone / administration & dosage
  • Thyrotropin-Releasing Hormone / pharmacology

Conflict of Interest Statement

Authors declare no conflict of interest.

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Citations

This article has been cited 8 times.
  1. Kirkwood NC, Hughes KJ, Stewart AJ. Prospective Case Series of Clinical Signs and Adrenocorticotrophin (ACTH) Concentrations in Seven Horses Transitioning to Pituitary Pars Intermedia Dysfunction (PPID).. Vet Sci 2022 Oct 17;9(10).
    doi: 10.3390/vetsci9100572pubmed: 36288186google scholar: lookup
  2. Kirkwood NC, Hughes KJ, Stewart AJ. Pituitary Pars Intermedia Dysfunction (PPID) in Horses.. Vet Sci 2022 Oct 10;9(10).
    doi: 10.3390/vetsci9100556pubmed: 36288169google scholar: lookup
  3. Hinrichsen SL, Yuen KY, Dryburgh EL, Bertin FR, Stewart AJ. Short-Term Effects of Temperature and Thyrotropin-Releasing Hormone Stimulation on Adrenocorticotropin Stability in Horses.. Animals (Basel) 2022 Jan 28;12(3).
    doi: 10.3390/ani12030324pubmed: 35158648google scholar: lookup
  4. 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.
    doi: 10.1111/jvim.16362pubmed: 35049089google scholar: lookup
  5. Kam YN, McKenzie K, Coyle M, Bertin FR. Repeatability of a thyrotropin-releasing hormone stimulation test for diagnosis of pituitary pars intermedia dysfunction in mature horses.. J Vet Intern Med 2021 Nov;35(6):2885-2890.
    doi: 10.1111/jvim.16281pubmed: 34642962google scholar: lookup
  6. Hicks GR, Fraser NS, Bertin FR. Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares.. Animals (Basel) 2021 Mar 20;11(3).
    doi: 10.3390/ani11030891pubmed: 33804751google scholar: lookup
  7. Horn R, Stewart AJ, Jackson KV, Dryburgh EL, Medina-Torres CE, Bertin FR. Clinical implications of using adrenocorticotropic hormone diagnostic cutoffs or reference intervals to diagnose pituitary pars intermedia dysfunction in mature horses.. J Vet Intern Med 2021 Jan;35(1):560-570.
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  8. Hu K, Stewart AJ, Yuen KY, Hinrichsen S, Dryburgh EL, Bertin FR. The effect of freeze-thaw cycles on determination of immunoreactive plasma adrenocorticotrophic hormone concentrations in horses.. J Vet Intern Med 2020 May;34(3):1350-1356.
    doi: 10.1111/jvim.15771pubmed: 32255541google scholar: lookup
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