A comparison of progesterone assays for determination of peripheral pregnane concentrations in the late pregnant mare.
Abstract: During the latter half of gestation in mares, there is a complex milieu of pregnanes in peripheral blood. Progesterone concentrations are often assessed by immunoassay during late gestation as a measure of pregnancy well-being; however, interpretation of results is complicated by the numerous cross-reacting pregnanes present in high concentrations during late gestation. Further, many mares are supplemented with an exogenous progestin, altrenogest, which may also cross-react with existing assays and further confound interpretation. The objectives of this study were: 1) to compare differences in pregnane concentrations determined with four immunoassays compared to LC-MS/MS and 2) to assess cross-reactivity observed with the same immunoassays, specifically considering pregnenolone (P5), progesterone (P4), 5α-dihydroprogesterone (DHP), allopregnanolone, and altrenogest. Blood samples from four healthy mares in late gestation were evaluated by immunoassay and by LC-MS/MS. Measured immuno-reactive progesterone (ir-progesterone) concentrations differed (p < 0.0001) between immunoassays, although results were highly correlated (r = 0.85-1.0; p < 0.001). Measured ir-progesterone concentrations by immunoassay were linearly associated (r = 0.68-0.76; p < 0.001) with concentrations of P5, P4, DHP, and allopregnanolone determined by LC-MS/MS. There was no detectable cross-reaction of altrenogest in any immunoassay, but varying degrees of cross-reactivity was observed with other pregnanes analyzed. These data confirm ir-progesterone concentrations during late gestation vary depending upon the assay used and the cross-reactivity to other pregnanes present in late gestation, although the synthetic progestin altrenogest did not affect the results of any immunoassay tested.
Copyright © 2017 Elsevier Inc. All rights reserved.
Publication Date: 2017-10-07 PubMed ID: 29059599DOI: 10.1016/j.theriogenology.2017.10.002Google Scholar: Lookup
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- Journal Article
Summary
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The research article centers around comparing and evaluating four different immunoassays to determine progesterone concentrations in late-pregnant mares. The study aims to better understand the assays’ cross-reactivity with different pregnanes in the blood samples of the mare during the latter part of gestation.
Objectives
The study aimed to:
- Compare four immunoassays with LC-MS/MS (liquid chromatography combined with mass spectrometry) for determining pregnane concentrations
- Evaluate the degree of cross-reaction between these immunoassays and various pregnanes namely pregnenolone (P5), progesterone (P4), 5α-dihydroprogesterone (DHP), allopregnanolone, and altrenogest.
Methodology
The researchers collected blood samples from four healthy mares in late gestation. These samples were then evaluated using immunoassays and the LC-MS/MS method. Further, varying degrees of cross-reactivity of the immunoassays with other pregnanes were assessed.
Findings
The study found that:
- There were significant differences in the progesterone concentrations ascertained by each of the tested immunoassays.
- The results were closely correlated despite the differences in measured progesterone concentrations.
- The concentrations measured by immunoassay were linearly associated with concentrations of P5, P4, DHP, and allopregnanolone determined by LC-MS/MS
- No detectable cross-reaction of altrenogest was found in any of the immunoassay tests, but varying degrees of cross-reactivity were observed with the other pregnanes under study.
Conclusion
These findings suggest that the type of assay used and its cross-reactivity with different pregnanes in the blood can influence the progesterone concentrations measured during the late stages of gestation. The study underscores the need for careful consideration and interpretation of progesterone assay results in late-pregnant mares, especially regarding potential cross-reactivity with other pregnanes in the blood. However, altrenogest, a synthetic progestin, did not affect the results of any immunoassay in the study.
Cite This Article
APA
Wynn MAA, Esteller-Vico A, Legacki EL, Conley AJ, Loux SC, Stanley SD, Curry TE, Squires EL, Troedsson MH, Ball BA.
(2017).
A comparison of progesterone assays for determination of peripheral pregnane concentrations in the late pregnant mare.
Theriogenology, 106, 127-133.
https://doi.org/10.1016/j.theriogenology.2017.10.002 Publication
Researcher Affiliations
- Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, United States.
- Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, United States.
- Department of Population Health and Reproduction, University of California, Davis, CA 95616, United States.
- Department of Population Health and Reproduction, University of California, Davis, CA 95616, United States.
- Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, United States.
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, United States.
- Department of Obstetrics and Gynecology, University of Kentucky, Lexington, KY 40546, United States.
- Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, United States.
- Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, United States.
- Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, United States. Electronic address: b.a.ball@uky.edu.
MeSH Terms
- Animals
- Antibodies / blood
- Chromatography, Liquid / methods
- Chromatography, Liquid / veterinary
- Female
- Horses / blood
- Horses / physiology
- Immunoassay / methods
- Immunoassay / veterinary
- Pregnancy
- Pregnancy, Animal / blood
- Pregnanes / blood
- Progesterone / blood
- Progesterone / chemistry
- Tandem Mass Spectrometry / methods
- Tandem Mass Spectrometry / veterinary
Citations
This article has been cited 3 times.- Grabowska A, Kozdrowski R. Relationship between estrus endometrial edema and progesterone production in pregnant mares two weeks after ovulation. BMC Vet Res 2022 Nov 21;18(1):414.
- Peter ID, Haron AW, Jesse FFA, Ajat M, Han MHW, Fitri WN, Yahaya MS, Alamaary MSM. Opportunities and challenges associated with fecal progesterone metabolite analysis. Vet World 2018 Nov;11(10):1466-1472.
- Porto ACRC, Redoan MA, Massoco CO, Furtado PV, Oliveira CA. Additional effects using progestins in mares on levels of thyroid hormones and steroids in neonates. Anim Reprod 2023;20(4):e20230029.
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