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Ireland JL, Lester A, Banse HE. Factors affecting measurement of basal adrenocorticotropic hormone in adult domestic equids: A scoping review. Vet J 2024; 304:106071. [PMID: 38341024 DOI: 10.1016/j.tvjl.2024.106071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024]
Abstract
Measurement of basal adrenocorticotropic hormone (ACTH) concentration is the most commonly used diagnostic test for pituitary pars intermedia dysfunction (PPID). Although several pre-analytical and analytical factors have been reported to affect basal ACTH concentrations in equids, the extent to which these have been evaluated in the context of PPID diagnosis is unclear. The objectives of this scoping review were to identify and systematically chart current evidence about pre-analytical and analytical factors affecting basal ACTH concentrations in adult domestic equids. Systematic searches of electronic databases and conference proceedings were undertaken in June 2022, repeated in October 2022 and updated in August 2023. English language publications published prior to these dates were included. Screening and data extraction were undertaken individually by the authors, using predefined criteria and a modified scoping review data extraction template. After removal of duplicates, 903 publications were identified, of which 235 abstracts were screened for eligibility and 134 publications met inclusion criteria. Time of year, exercise, breed/type and transportation were the factors most frequently associated with significant increases in ACTH concentration (n = 26, 16, 13 and 10 publications, respectively). Only 25 publications reported inclusion of PPID cases in the study population, therefore the relationship between many factors affecting basal ACTH concentration and diagnostic accuracy for PPID remains undefined. However, several factors were identified that could impact interpretation of basal ACTH results. Findings also highlight the need for detailed reporting of pre-analytical and analytical conditions in future research to facilitate translation of evidence to practice.
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Affiliation(s)
- J L Ireland
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst CH64 7TE, Cheshire, UK.
| | - A Lester
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst CH64 7TE, Cheshire, UK
| | - H E Banse
- School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
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Ireland J, McGowan C. Deciphering reference intervals and clinical decision limits in equine endocrine diagnostic testing. Vet J 2023; 300-302:106037. [PMID: 37832629 DOI: 10.1016/j.tvjl.2023.106037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 10/05/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023]
Abstract
Reference intervals (RIs) and clinical decision limits (CDLs) are frequently established to facilitate interpretation of values of endocrine biomarkers in the diagnosis of disease. Despite their commonplace use in clinical decision-making, these concepts can be confused. Comparing a test result with a RI provides an estimation as to whether or not the individual is healthy, whereas comparison with a CDL facilitates identification of individuals with a particular disease state or at greater risk of adverse clinical outcomes. In practice, there will also be a range of results for which the discriminative ability of the test is insufficient to inform a specific diagnostic decision. Including a range of uncertain test results, or 'grey zone', between positive and negative avoids the constraint of a binary decision in classifying an individual with a test value above (or below) a single cut-off value as diseased. This review will detail the application of both RIs and CDLs, including defining the range of uncertain test results, in the context of equine endocrinology.
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Affiliation(s)
- Joanne Ireland
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst, CH64 7TE Cheshire, UK.
| | - Catherine McGowan
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst, CH64 7TE Cheshire, UK
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Delarocque J, Feige K, Carslake HB, Durham AE, Fey K, Warnken T. Development of a Web App to Convert Blood Insulin Concentrations among Various Immunoassays Used in Horses. Animals (Basel) 2023; 13:2704. [PMID: 37684968 PMCID: PMC10487020 DOI: 10.3390/ani13172704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/18/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
The measurement of the blood insulin concentration, and comparison to cut-offs, is essential in diagnosing insulin dysregulation, a common equine endocrinopathy. However, different insulin assays provide disparate results. We aimed to ease comparison between assays by compiling original and published data into a web app to convert insulin measurements from one assay to another. Data were available for ADVIA Centaur insulin chemiluminescent immunoassay (CLIA), Beckman Coulter insulin radioimmunoassay (RIA), Immulite 1000 CLIA, Immulite 2000 CLIA, Immulite 2000 XPi CLIA, Mercodia equine insulin enzyme-linked immunosorbent assay (ELISA), and Millipore porcine insulin RIA. Linear models were fitted for 13 assay pairs using non-decreasing splines, and integrated into this app. Assay comparisons including data from several studies showed a lower performance. This indicates technical variation between laboratories, which has not been described before, but is relevant when diagnostic measurements and cut-offs are provided by different laboratories. Nevertheless, the models' overall high performance (median r2 = 0.94; range 0.57-1.00) supports their use to interpret results from diagnostic insulin measurements when the reference assay is unavailable, and to compare values obtained from different assays.
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Affiliation(s)
- Julien Delarocque
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559 Hannover, Germany
| | - Karsten Feige
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559 Hannover, Germany
| | - Harry B. Carslake
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Leahurst, Neston CH64 7TE, Cheshire, UK
| | - Andy E. Durham
- The Liphook Equine Hospital, Forest Mere, Liphook GU30 7JG, Hampshire, UK
| | - Kerstin Fey
- Equine Clinic, Internal Medicine, Faculty of Veterinary Medicine, Justus-Liebig-University of Giessen, Frankfurter Str. 126, 35392 Giessen, Germany
| | - Tobias Warnken
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559 Hannover, Germany
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Delarocque J, Reiche DB, Meier AD, Warnken T, Feige K, Sillence MN. Metabolic profile distinguishes laminitis-susceptible and -resistant ponies before and after feeding a high sugar diet. BMC Vet Res 2021; 17:56. [PMID: 33509165 PMCID: PMC7841998 DOI: 10.1186/s12917-021-02763-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/13/2021] [Indexed: 12/31/2022] Open
Abstract
Background Insulin dysregulation (ID) is a key risk factor for equine endocrinopathic laminitis, but in many cases ID can only be assessed accurately using dynamic tests. The identification of other biomarkers could provide an alternative or adjunct diagnostic method, to allow early intervention before laminitis develops. The present study characterised the metabolome of ponies with varying degrees of ID using basal and postprandial plasma samples obtained during a previous study, which examined the predictive power of blood insulin levels for the development of laminitis, in ponies fed a high-sugar diet. Samples from 10 pre-laminitic (PL – subsequently developed laminitis) and 10 non-laminitic (NL – did not develop laminitis) ponies were used in a targeted metabolomic assay. Differential concentration and pathway analysis were performed using linear models and global tests. Results Significant changes in the concentration of six glycerophospholipids (adj. P ≤ 0.024) and a global enrichment of the glucose-alanine cycle (adj. P = 0.048) were found to characterise the response of PL ponies to the high-sugar diet. In contrast, the metabolites showed no significant association with the presence or absence of pituitary pars intermedia dysfunction in all ponies. Conclusions The present results suggest that ID and laminitis risk are associated with alterations in the glycerophospholipid and glucose metabolism, which may help understand and explain some molecular processes causing or resulting from these conditions. The prognostic value of the identified biomarkers for laminitis remains to be investigated in further metabolomic trials in horses and ponies. Supplementary Information The online version contains supplementary material available at 10.1186/s12917-021-02763-7.
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Affiliation(s)
- Julien Delarocque
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, 30559, Hannover, Germany.
| | - Dania B Reiche
- Boehringer Ingelheim Vetmedica GmbH, 55216, Ingelheim am Rhein, Germany
| | - Alexandra D Meier
- Biology and Environmental Science School, Queensland University of Technology, Brisbane, Queensland, 4000, Australia
| | - Tobias Warnken
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, 30559, Hannover, Germany
| | - Karsten Feige
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, 30559, Hannover, Germany
| | - Martin N Sillence
- Biology and Environmental Science School, Queensland University of Technology, Brisbane, Queensland, 4000, Australia
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Durham AE, Frank N, McGowan CM, Menzies-Gow NJ, Roelfsema E, Vervuert I, Feige K, Fey K. ECEIM consensus statement on equine metabolic syndrome. J Vet Intern Med 2019; 33:335-349. [PMID: 30724412 PMCID: PMC6430910 DOI: 10.1111/jvim.15423] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/11/2019] [Indexed: 12/26/2022] Open
Abstract
Equine metabolic syndrome (EMS) is a widely recognized collection of risk factors for endocrinopathic laminitis. The most important of these risk factors is insulin dysregulation (ID). Clinicians and horse owners must recognize the presence of these risk factors so that they can be targeted and controlled to reduce the risk of laminitis attacks. Diagnosis of EMS is based partly on the horse's history and clinical examination findings, and partly on laboratory testing. Several choices of test exist which examine different facets of ID and other related metabolic disturbances. EMS is controlled mainly by dietary strategies and exercise programs that aim to improve insulin regulation and decrease obesity where present. In some cases, pharmacologic aids might be useful. Management of an EMS case is a long‐term strategy requiring diligence and discipline by the horse's carer and support and guidance from their veterinarians.
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Affiliation(s)
| | - Nicholas Frank
- Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts
| | - Cathy M McGowan
- Institute of Veterinary Science, University of Liverpool, Neston, United Kingdom
| | - Nicola J Menzies-Gow
- Department of clinical sciences and services, Royal Veterinary College, Herts, United Kingdom
| | - Ellen Roelfsema
- Department of Equine Sciences, Utrecht University, Utrecht, The Netherlands
| | - Ingrid Vervuert
- Faculty of Veterinary Medicine, University of Leipzig, Institute of Animal Nutrition, Nutrition Diseases and Dietetics, Leipzig, Germany
| | - Karsten Feige
- Clinic for Horses, University of Veterinary Medicine Hannover, Germany
| | - Kerstin Fey
- Equine Clinic, Internal Medicine, Faculty of Veterinary Medicine, Justus-Liebig-University of Giessen, Giessen, Germany
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Meier AD, de Laat MA, Reiche DB, Pollitt CC, Walsh DM, McGree JM, Sillence MN. The oral glucose test predicts laminitis risk in ponies fed a diet high in nonstructural carbohydrates. Domest Anim Endocrinol 2018; 63:1-9. [PMID: 29172109 DOI: 10.1016/j.domaniend.2017.10.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 10/18/2022]
Abstract
The aim of this study was to investigate the relationship between laminitis development in ponies and insulin/glucose concentrations in response to the oral glucose test (OGT) and a dietary challenge high in nonstructural carbohydrates (NSCs). After undergoing an OGT (1 g dextrose/kg BW in feed), 37 ponies with 2-h serum insulin concentrations ranging from 22 to 1,133 μIU/mL were subjected to a diet challenge period (DCP), consuming 12 g NSC/kg BW/d for up to 18 d. Insulin and glucose responses were measured on day 2 of the DCP. Clinical laminitis was diagnosed by blinded experts and confirmed radiographically. Basal ACTH levels and clinical signs were assessed to investigate concurrent putative pituitary pars intermedia dysfunction (PPID). The diet induced Obel grade 1 or 2 laminitis in 14 ponies (38%). The ponies that developed laminitis had higher maximum concentrations of blood glucose (P = 0.04) and serum insulin (P = 0.02) in response to the diet. The geometric mean (95% CI) blood glucose concentration for laminitis cases was 14.9 (12.9-17.2) mM, compared to 10.7 (9.2-12.5) mM for ponies who did not develop laminitis. Similarly, the geometric mean (95% CI) for serum insulin was 396 (301-520) μIU/mL for laminitis cases, compared to 216 (148-316) μIU/mL for ponies who did not develop laminitis. Laminitis incidence was likewise associated with insulin concentrations measured during the OGT. Laminitis occurred at frequencies of 0% (0/7) if postdextrose insulin (μIU/mL) was <50; 35% (8/23) if insulin was 50 to 195; and 86% (6/7) if insulin was >195 μIU/mL. Basal ACTH concentrations were above seasonally accepted reference ranges in 16/37 ponies, and 8 of these animals (50%) developed laminitis. This included all 5 ponies in the study that had clinical signs of PPID (100%). In contrast, hyperinsulinemia and laminitis occurred in only 3/11 ponies (27%) with elevated ACTH concentrations and no clinical signs of PPID (P = 0.009). Thus, laminitis occurrence was associated with higher glucose and insulin responses to both the OGT and challenge diet, and the frequency of laminitis can be predicted based on insulin and glucose hyperresponsiveness to these oral carbohydrate challenges.
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Affiliation(s)
- A D Meier
- Earth, Environmental and Biological Sciences School, Queensland University of Technology, Queensland, Australia
| | - M A de Laat
- Earth, Environmental and Biological Sciences School, Queensland University of Technology, Queensland, Australia
| | - D B Reiche
- Boehringer Ingelheim Vetmedica, Ingelheim am Rhein, Germany
| | - C C Pollitt
- Australian Equine Laminitis Research Unit, School of Veterinary Science, University of Queensland, Queensland, Australia
| | - D M Walsh
- Animal Health Foundation, Pacific, Missouri, USA
| | - J M McGree
- School of Mathematical Sciences, Queensland University of Technology, Queensland, Australia
| | - M N Sillence
- Earth, Environmental and Biological Sciences School, Queensland University of Technology, Queensland, Australia.
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