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Equine veterinary journal2020; 53(2); 250-260; doi: 10.1111/evj.13292

Clinically and temporally specific diagnostic thresholds for plasma ACTH in the horse.

Abstract: Pituitary pars intermedia dysfunction (PPID) is commonly investigated using plasma ACTH concentrations but problems exist with currently available diagnostic thresholds. Objective: To derive temporally specific diagnostic thresholds for equine plasma ACTH concentration to be used alongside clinical judgement in each individual week of the year and appropriate for the degree of clinical suspicion in any given case. Furthermore, to apply these thresholds to compare the prevalence of high and low ACTH in two subgroups of animals with high and low clinical suspicion of PPID. Methods: A retrospective population study examining a large laboratory database of equine plasma ACTH concentrations using an indirect approach to calculate diagnostic thresholds. Methods: Logs of plasma ACTH concentrations from 75 892 individual horses were examined using robust L estimation of mixtures of two normal distributions in categories of each week and month of the year. Thresholds dividing the two populations of high-ACTH and low-ACTH horses were then established at different levels of sensitivity and specificity and compared with clinical subgroups of horses divided based on reported clinical signs, as having high (n = 4036) or low (n = 3022) clinical suspicion of PPID. Results: For most of the year there were small interweek differences in diagnostic thresholds. However, from mid-June to early-December diagnostic thresholds showed greater interweek variability, reaching a maximum in late September and early October. Grouping of high- and low-ACTH compared favourably with grouping based on clinical signs. Conclusions: Given the multiple sources of diagnostic samples, pre-analytical data could not be fully verified. Conclusions: Diagnostic thresholds for equine plasma ACTH vary through the year. It is especially important to consider the temporally specific threshold between June and December. Different clinical thresholds can be used depending on the case circumstances and whether a false-positive or false-negative diagnosis is deemed least desirable.
© 2020 EVJ Ltd.
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Publication Date: 2020-06-23 PubMed ID: 32470177DOI: 10.1111/evj.13292Google 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 establishes time-based diagnostic thresholds for the concentration of Adrenocorticotropic hormone (ACTH) in horse plasma, which assists in the detection of Pituitary pars intermedia dysfunction (PPID). The study also highlights the importance of these temporal thresholds in determining the prevalence of high and low ACTH, particularly relevant when there’s a high or low clinical suspicion of PPID.

Objective and Methodology

  • The objective of the study was to identify specific diagnostic thresholds for equine plasma ACTH concentration for each week of the year. The goal was to have a more accurate and temporally specific way of diagnosing PPID in horses.
  • The research also aimed to compare the prevalence of high and low ACTH in two subgroups of horses, those with high clinical suspicion of PPID and those with low suspicion.
  • The researchers carried out a retrospective population study, where they examined logs of plasma ACTH concentrations from 75,892 individual horses using robust L estimation of mixtures of two normal distributions.
  • The data was categorized by each week and month of the year. Using this data, thresholds that divide the high and low ACTH populations were established.

Key Findings

  • Interweek differences in diagnostic thresholds were minimal for most parts of the year.
  • However, from mid-June to early-December, these thresholds demonstrated increased variability, peaking in late September and early October.
  • The study found that grouping horses based on high and low ACTH concentration aligned favorably with grouping based on reported clinical signs of PPID.

Conclusion and Implications

  • Since the multiple sources of diagnostic samples prevented full verification of pre-analytical data, validation of the findings may be required.
  • The study concludes that diagnostic thresholds for equine plasma ACTH vary throughout the year, highlighting the importance of considering these temporal variations, especially between June and December.
  • The study also recommends that different clinical thresholds should be applied based on the case circumstances and whether a false-positive or false-negative diagnosis would have a more significant impact.

Cite This Article

APA
Durham AE, Clarke BR, Potier JFN, Hammarstrand R, Malone GL. (2020). Clinically and temporally specific diagnostic thresholds for plasma ACTH in the horse. Equine Vet J, 53(2), 250-260. https://doi.org/10.1111/evj.13292

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 53
Issue: 2
Pages: 250-260

Researcher Affiliations

Durham, Andy E
  • The Liphook Equine Hospital, Liphook, UK.
Clarke, Brenton R
  • Mathematics and Statistics, ITMAS, College of Science, Health, Engineering and Education, Murdoch University, Western Australia, Australia.
Potier, Julie F N
  • The Liphook Equine Hospital, Liphook, UK.
Hammarstrand, Robert
  • Mathematics and Statistics, ITMAS, College of Science, Health, Engineering and Education, Murdoch University, Western Australia, Australia.
Malone, George L
  • Mathematics and Statistics, ITMAS, College of Science, Health, Engineering and Education, Murdoch University, Western Australia, Australia.

MeSH Terms

  • Adrenocorticotropic Hormone / metabolism
  • Animals
  • Horse Diseases / diagnosis
  • Horses
  • Pituitary Diseases / diagnosis
  • Pituitary Diseases / veterinary
  • Pituitary Gland, Intermediate / metabolism
  • Plasma / metabolism
  • Retrospective Studies

Grant Funding

  • Murdoch University
  • Boehringer Ingelheim

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Citations

This article has been cited 13 times.
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