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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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Frers F, Delarocque J, Huber K, Feige K, Warnken T. Comparison of a modified 2-step insulin response test performed with porcine zinc insulin and an oral glucose test to detect hyperinsulinemic Icelandic horses. Vet J 2023; 298-299:106012. [PMID: 37348701 DOI: 10.1016/j.tvjl.2023.106012] [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: 09/23/2022] [Revised: 06/10/2023] [Accepted: 06/19/2023] [Indexed: 06/24/2023]
Abstract
Both, oral and intravenous (IV) testing protocols, are recommended and still used to detect insulin dysregulation (ID) in equids. However, IV tests mainly focus on peripheral insulin resistance (IR), while oral tests assess hyperinsulinemia (HI), which are different aspects of ID. The objective of this study was to describe if horses with HI also demonstrate IR and consequently can be detected by a modified 2-step insulin response test (2-step IRT) performed with a veterinary approved porcine zinc insulin (PZI). Twelve Icelandic horses were subjected to an OGT and 2-step IRT in a crossover study. Serum insulin concentrations during the OGT revealed that six horses were hyperinsulinemic (HI) while six were not (NON-HI). To describe the glucose response to IV injected PZI, the decline of plasma glucose concentration within the first 30 min was analyzed. Glucose reduction was similar in horses with and without HI during the 2-step IRT over time. Additionally, none of the horses reached a glucose reduction of ≥ 50% at 30 min. The results of the present study indicated that a comparable insulin mediated glucose uptake may be observed in horses with and without HI during a modified 2-step IRT. While six out of twelve horses were identified as HI by the OGT, all twelve horses were identified as IR by the modified 2-step IRT performed with PZI underlining the importance, but difficulty in choosing the right diagnostic tool in clinical settings to assess ID.
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Affiliation(s)
- F Frers
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Buenteweg 9, 30559 Hanover, Germany.
| | - J Delarocque
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Buenteweg 9, 30559 Hanover, Germany
| | - K Huber
- Institute of Animal Science, Faculty of Agricultural Sciences, University of Hohenheim, Fruwirthstr. 35, 70599 Stuttgart, Germany
| | - K Feige
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Buenteweg 9, 30559 Hanover, Germany
| | - T Warnken
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Buenteweg 9, 30559 Hanover, Germany
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Go YY, Hazard NW, Balasuriya UBR, Chapman AM, Fitton NS, Kenéz Á, Andrews FM. Clinical evaluation of the Immulite® 1000 chemiluminescent immunoassay for measurement of equine serum insulin. Front Vet Sci 2023; 10:1018230. [PMID: 37051514 PMCID: PMC10083388 DOI: 10.3389/fvets.2023.1018230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 03/06/2023] [Indexed: 03/29/2023] Open
Abstract
IntroductionAccurate quantitative analysis of equine insulin in blood samples is critical for assessing hyperinsulinemia in horses. Although there are various laboratory methods for evaluating equine serum insulin, different immunoassays show significant discrepancies between the determined insulin concentrations and are often not comparable. The aim of this study was to evaluate the Immulite® 1000 chemiluminescent immunoassay (CLIA) to establish independent laboratory and assay-specific cut values to provide an accurate diagnosis of hyperinsulinemia in horses. Thus, the analytical and clinical performance of Immulite® 1000 CLIA in terms of precision (intra- and inter-assay coefficient of variance, CV) and recovery upon dilution were evaluated and compared with radioimmunoassay (RIA), which has been previously validated for use in horses.Material and methodsArchived serum samples (n = 106) from six Quarter horse mares enrolled in the glucose phase of a Frequently Sampled Insulin and Glucose Test (FSIGT) study were used to measure blood insulin.ResultsThe Immulite® 1000 CLIA had good precision with acceptable intra- and inter-assay CVs, adequate recovery on dilution, and a strong correlation with the RIA (r = 0.974, P < 0.0001), with constant bias resulting in consistently lower values.DiscussionOn this basis, the Immulite® 1000 Insulin Assay is valid for measuring equine serum insulin for diagnostic and monitoring purposes when cut values are appropriately adjusted.
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Affiliation(s)
- Yun Young Go
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Nicole W. Hazard
- Louisiana Animal Disease Diagnostic Laboratory and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, United States
| | - Udeni B. R. Balasuriya
- Louisiana Animal Disease Diagnostic Laboratory and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, United States
| | - Anna M. Chapman
- Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, United States
| | | | - Ákos Kenéz
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Frank M. Andrews
- Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, United States
- *Correspondence: Frank M. Andrews
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Williams NJ, Furr M, Navas de Solis C, Campolo A, Davis M, Lacombe VA. Investigating the Relationship Between Cardiac Function and Insulin Sensitivity in Horses: A Pilot Study. Front Vet Sci 2022; 9:899951. [PMID: 35873691 PMCID: PMC9305457 DOI: 10.3389/fvets.2022.899951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 06/17/2022] [Indexed: 11/13/2022] Open
Abstract
Metabolic syndrome in humans is commonly associated with cardiovascular dysfunction, including atrial fibrillation and left ventricular diastolic dysfunction. Although many differences exist between human and equine metabolic syndrome, both of these conditions share some degree of insulin resistance. The aims of this pilot study were to investigate the relationship between insulin sensitivity and cardiac function. Seven horses (five mares, two geldings, aged 17.2 ± 4.2 years, weight 524 ± 73 kg) underwent insulin-modified frequently sampled intravenous glucose tolerance testing to determine insulin sensitivity (mean 2.21 ± 0.03 × 10−4 L/min/mU). Standard echocardiograms were performed on each horse, including two-dimensional, M-mode, and pulse-wave tissue Doppler imaging. Pearson and Spearman correlation analyses were used to determine the association of insulin sensitivity with echocardiographic measures of cardiac function in 5 horses. Insulin sensitivity was found to be significantly correlated with peak myocardial velocity during late diastole (r = 0.89, P = 0.0419), ratio between peak myocardial velocity in early and late diastole (r = −0.92, P = 0.0263), isovolumetric relaxation time (r = −0.97, P = 0.0072), and isovolumetric contraction time (ρ = −0.90, P = 0.0374). These preliminary data suggest that decreased insulin sensitivity is correlated with alterations in both systolic and diastolic function, as measured with tissue Doppler imaging (TDI). Due to the small sample size of this study, the relationship between insulin sensitivity and myocardial function in horses requires further investigation.
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Affiliation(s)
- Natasha J. Williams
- Department of Clinical Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
- *Correspondence: Natasha J. Williams
| | - Martin Furr
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Cristobal Navas de Solis
- Department of Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Allison Campolo
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Michael Davis
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Véronique A. Lacombe
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
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Kinsella HM, Hostnik LD, Snyder HA, Mazur SE, Kamr AM, Burns TA, Mossbarger JC, Toribio RE. Comparison of insulin sensitivity between healthy neonatal foals and horses using minimal model analysis. PLoS One 2022; 17:e0262584. [PMID: 35030228 PMCID: PMC8759699 DOI: 10.1371/journal.pone.0262584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 12/29/2021] [Indexed: 11/18/2022] Open
Abstract
The equine neonate is considered to have impaired glucose tolerance due to delayed maturation of the pancreatic endocrine system. Few studies have investigated insulin sensitivity in newborn foals using dynamic testing methods. The objective of this study was to assess insulin sensitivity by comparing the insulin-modified frequently sampled intravenous glucose tolerance test (I-FSIGTT) between neonatal foals and adult horses. This study was performed on healthy neonatal foals (n = 12), 24 to 60 hours of age, and horses (n = 8), 3 to 14 years of age using dextrose (300 mg/kg IV) and insulin (0.02 IU/kg IV). Insulin sensitivity (SI), acute insulin response to glucose (AIRg), glucose effectiveness (Sg), and disposition index (DI) were calculated using minimal model analysis. Proxy measurements were calculated using fasting insulin and glucose concentrations. Nonparametric statistical methods were used for analysis and reported as median and interquartile range (IQR). SI was significantly higher in foals (18.3 L·min-1· μIU-1 [13.4–28.4]) compared to horses (0.9 L·min-1· μIU-1 [0.5–1.1]); (p < 0.0001). DI was higher in foals (12 × 103 [8 × 103−14 × 103]) compared to horses (4 × 102 [2 × 102−7 × 102]); (p < 0.0001). AIRg and Sg were not different between foals and horses. The modified insulin to glucose ratio (MIRG) was lower in foals (1.72 μIUinsulin2/10·L·mgglucose [1.43–2.68]) compared to horses (3.91 μIU insulin2/10·L·mgglucose [2.57–7.89]); (p = 0.009). The homeostasis model assessment of beta cell function (HOMA-BC%) was higher in horses (78.4% [43–116]) compared to foals (23.2% [17.8–42.2]); (p = 0.0096). Our results suggest that healthy neonatal foals are insulin sensitive in the first days of life, which contradicts current literature regarding the equine neonate. Newborn foals may be more insulin sensitive immediately after birth as an evolutionary adaptation to conserve energy during the transition to extrauterine life.
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Affiliation(s)
- Hannah M. Kinsella
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Laura D. Hostnik
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
| | - Hailey A. Snyder
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Sarah E. Mazur
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Ahmed M. Kamr
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt
| | - Teresa A. Burns
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | | | - Ramiro E. Toribio
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
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Mendoza FJ, Buzon-Cuevas A, Toribio RE, Perez-Ecija A. Characterisation of the oral glucose and sugar tolerance tests and the enteroinsular axis response in healthy adult donkeys. Equine Vet J 2021; 54:1123-1132. [PMID: 34897779 DOI: 10.1111/evj.13544] [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: 06/23/2021] [Revised: 10/18/2021] [Accepted: 12/09/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Insulin dysregulation (ID) is diagnosed in horses and ponies using oral glucose (OGTT) and oral sugar (OSTT) tolerance tests. The enteroinsular axis plays a major role in postprandial glucose disposal and insulin response in horses, ponies and foals. The insulin and incretin response to oral carbohydrate challenges has not been characterised in donkeys. OBJECTIVES (a) To characterise OGTT and OSTT, and (b) to assess the plasma incretin response to OGTT and OSTT in healthy donkeys. STUDY DESIGN In vivo experiments. METHODS Six healthy adult female Andalusian donkeys were challenged with OGTT (1 g/kg glucose, 20% solution by nasogastric tube) and OSTT (0.45 mL/kg corn syrup orally by syringe) with a 1-week washout. Blood samples were collected for glucose (spectrophotometry), insulin (radioimmunoassay), glucose-dependent insulinotropic polypeptide (GIP, ELISA) and active glucagon-like peptide-1 (aGLP-1, ELISA) determination over 6 hours. Curves were analysed and proxies calculated. RESULTS Glucose and insulin concentrations peaked at 180 minutes in OGTT, but at 300 and 150 minutes in OSTT, respectively. Plasma GIP concentrations increased in the OGTT and OSTT (peaked at 180 and 360 minutes, respectively), but aGLP-1 increased only in OGTT (240 minutes). MAIN LIMITATIONS Single breed, narrow age and sample, diet, season and not having donkeys with evidence of ID to provide clinical validation. CONCLUSIONS Donkeys have a functional enteroinsular axis that is activated by enteral carbohydrates. Donkeys have evident endocrine differences with horses, supporting the validation of the OSTT and OGTT to assess insulin sensitivity in this species to avoid extrapolation from horses.
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Affiliation(s)
- Francisco J Mendoza
- Department of Animal Medicine and Surgery, University of Cordoba, Cordoba, Spain
| | - Antonio Buzon-Cuevas
- Department of Animal Medicine and Surgery, University of Cordoba, Cordoba, Spain
| | - Ramiro E Toribio
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio, USA
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McFarlane D. Diagnostic Testing for Equine Endocrine Diseases: Confirmation Versus Confusion. Vet Clin North Am Equine Pract 2019; 35:327-338. [PMID: 31076223 DOI: 10.1016/j.cveq.2019.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Despite there being only 2 common endocrine diseases in horses, pituitary pars intermedia dysfunction (PPID) and equine metabolic syndrome (EMS), diagnosis is still confusing. Failing to consider horse factors and treating based on laboratory results only have caused many animals to receive lifelong drug treatment unnecessarily. Increased plasma ACTH, baseline or TRH stimulated, supports a diagnosis of PPID; however, breed, age, thriftiness, illness, coat color, geography, diet, and season also affect ACTH concentration. Insulin dysregulation, the hallmark of EMS, can result from insulin resistance or excessive postprandial insulin release. Each requires a different diagnostic test to reach a diagnosis.
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Affiliation(s)
- Dianne McFarlane
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, 264 McElroy Hall, CVHS-OSU, Stillwater, OK 74078, USA.
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Meier A, de Laat M, Reiche D, Fitzgerald D, Sillence M. The efficacy and safety of velagliflozin over 16 weeks as a treatment for insulin dysregulation in ponies. BMC Vet Res 2019; 15:65. [PMID: 30808423 PMCID: PMC6390376 DOI: 10.1186/s12917-019-1811-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 02/19/2019] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND A previous six-week (wk) study demonstrated the potential of the sodium-glucose linked transport inhibitor velagliflozin as a novel treatment for equine insulin dysregulation. The present study examined the safety and efficacy of velagliflozin over 16 wk. of treatment, and over 4 wk. of withdrawal. Twenty-four insulin dysregulated ponies were selected, based on their hyper-responsiveness to a diet challenge meal containing 3.8 g non-structural carbohydrates (NSC)/kg bodyweight (BW). Ponies with serum insulin > 90 μIU/mL either 2 or 4 h after feeding were enrolled, and randomly allocated to receive either velagliflozin (0.3 mg/kg BW orally once daily, n = 12), or a placebo (n = 10-12) for 16 wk. The subjects were fed 7.5 g NSC/kg BW/day to maintain a fat body condition. Safety was assessed through daily monitoring, veterinary examination, and the measurement of fasting blood glucose, biochemistry and haematology. Efficacy at reducing post-prandial hyperinsulinemia was assessed using a diet challenge every 8 wk. during treatment and 4 wk. after withdrawal. RESULTS Velagliflozin was well accepted by all subjects and caused no adverse effects or hypoglycaemia. Post-prandial serum insulin (insulin Cmax) did not change significantly in the control animals over the entire study period (P = 0.101). In contrast, insulin Cmax (mean ± SE) concentrations fell over time in the velagliflozin-treated group from 205 ± 25 μIU/mL in wk. 0, to 119 ± 19 μIU/mL (P = 0.015) and 117 ± 15 μIU/ml (P = 0.029) after 8 and 16 wk. of treatment, respectively. Although the insulin Cmax in this group was not significantly lower than in controls at wk-8 (P = 0.061), it was lower at wk-16 (P = 0.003), and all 12 treated ponies were below the previously-determined risk threshold for laminitis at this time. After 4 wk. withdrawal, the insulin Cmax returned to 199 ± 36 μIU/mL in the treated group, with no rebound effect. CONCLUSIONS Velagliflozin appears to be a promising and safe treatment for equine insulin dysregulation, bringing post-prandial insulin concentrations below the laminitis risk threshold, albeit without normalising them.
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Affiliation(s)
- A. Meier
- Earth, Environmental and Biological Sciences School, Queensland University of Technology (QUT), Brisbane, Queensland 4000 Australia
| | - M. de Laat
- Earth, Environmental and Biological Sciences School, Queensland University of Technology (QUT), Brisbane, Queensland 4000 Australia
| | - D. Reiche
- Boehringer Ingelheim Vetmedica, 55218 Ingelheim am Rhein, Germany
| | - D. Fitzgerald
- Earth, Environmental and Biological Sciences School, Queensland University of Technology (QUT), Brisbane, Queensland 4000 Australia
| | - M. Sillence
- Earth, Environmental and Biological Sciences School, Queensland University of Technology (QUT), 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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Jocelyn NA, Harris PA, Menzies-Gow NJ. Effect of varying the dose of corn syrup on the insulin and glucose response to the oral sugar test. Equine Vet J 2018; 50:836-841. [DOI: 10.1111/evj.12826] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 02/26/2018] [Indexed: 12/27/2022]
Affiliation(s)
- N. A. Jocelyn
- Department of Clinical Sciences and Services; Royal Veterinary College; London UK
| | - P. A. Harris
- WALTHAM Centre for Pet Nutrition; Melton Mowbray, Leicestershire UK
| | - N. J. Menzies-Gow
- Department of Clinical Sciences and Services; Royal Veterinary College; London UK
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11
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Bertin FR, Laat MA. The diagnosis of equine insulin dysregulation. Equine Vet J 2017; 49:570-576. [DOI: 10.1111/evj.12703] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/16/2017] [Indexed: 12/18/2022]
Affiliation(s)
- F. R. Bertin
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - M. A. Laat
- Science and Engineering Faculty Queensland University of Technology Brisbane Queensland Australia
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12
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Carslake HB, Pinchbeck GL, McGowan CM. Evaluation of a Chemiluminescent Immunoassay for Measurement of Equine Insulin. J Vet Intern Med 2017; 31:568-574. [PMID: 28124389 PMCID: PMC5354037 DOI: 10.1111/jvim.14657] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/30/2016] [Accepted: 12/20/2016] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Many diagnostic tests for insulin dysregulation use reference intervals established with an insulin radioimmunoassay (RIA) that is no longer available. A chemiluminescent immunoassay (CLIA) is commonly used for the measurement of serum insulin concentration in clinical practice but requires further validation, especially at clinically relevant reference intervals. OBJECTIVES To evaluate the CLIA for measurement of equine insulin and compare it to the previously validated, but now unavailable RIA. SAMPLES Equine serum samples (n = 78) from clinical and experimental studies. METHODS In this experimental study, performance of the CLIA was evaluated using standard variables, including comparison with the RIA. Continuous and binary outcomes were analyzed. RESULTS The CLIA showed good intra-assay (coefficient of variation [CV], 1.8-2.4%) and interassay (CV, 3-7.1%) precision. Acceptable recovery on dilution (100 ± 10%) was achieved only at dilutions <1:1. Recovery on addition was acceptable. Comparison of the CLIA and RIA showed strong positive correlation (r = 0.91-0.98), with fixed and proportional bias. At 3 diagnostic cutoffs, sensitivity of CLIA compared with RIA ranged from 67 to 100% and specificity from 96 to 100%. CONCLUSIONS AND CLINICAL IMPORTANCE The CLIA is a highly repeatable assay which is suitable for within- and between-horse comparisons. Dilution of high concentration samples should be performed with charcoal-stripped serum (CSS) and at the lowest dilution factor possible. At concentrations commonly used for diagnosis of insulin dysregulation (≤100 μIU/mL), results from the CLIA tend to be lower than from the RIA and should be interpreted accordingly. Further standardization of equine insulin assays is required.
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Affiliation(s)
- H B Carslake
- Institute of Aging and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Neston, Wirral, UK
| | - G L Pinchbeck
- Institute of Infection and Global Health, Faculty of Health and Life Sciences, University of Liverpool, Neston, Wirral, UK
| | - C M McGowan
- Institute of Aging and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Neston, Wirral, UK
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Warnken T, Huber K, Feige K. Comparison of three different methods for the quantification of equine insulin. BMC Vet Res 2016; 12:196. [PMID: 27613127 PMCID: PMC5016943 DOI: 10.1186/s12917-016-0828-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 09/01/2016] [Indexed: 11/17/2022] Open
Abstract
Background Exact analysis of equine insulin in blood samples is the key element for assessing insulin resistance or insulin dysregulation in horses. However, previous studies indicated marked differences in insulin concentrations obtained from sample analyses with different immunoassays. Most assays used in veterinary medicine are originally designed for use in human diagnostics and are based on antibodies directed against human insulin, although amino acid sequences between equine and human insulin differ. Species-specific assays are being used more frequently and seem to provide advantages compared to human-specific assays. The aim of this study was to compare three immunoassays, one porcine-specific insulin enzyme-linked immunosorbent assay (ELISA), advertised to be specific for equine insulin, one porcine-specific insulin radioimmunoassay (RIA) and one human-specific insulin chemiluminescence immunoassay (CLIA), all three widely used in veterinary laboratories for the analysis of equine insulin. Furthermore, we tested their clinical applicability in assessing insulin resistance and dysregulation by analysis of basal blood and blood samples obtained during a dynamic diagnostic stimulation test (OGT) with elevated insulin concentrations. Results Insulin values obtained from the ELISA, RIA and CLIA, investigated for analyses of basal blood samples differed significantly between all three assays. Analyses of samples obtained during dynamic diagnostic stimulation testing with consecutively higher insulin concentrations revealed significantly (p < 0.001) lower insulin concentrations supplied by the CLIA compared to the ELISA. However, values measured by ELISA were intermediate and not different to those measured by RIA. Calculated recovery upon dilution, as a marker for assay accuracy in diluted samples, was 98 ± 4 % for ELISA, 160 ± 41 % for RIA and 101 ± 11 % for CLIA. Conclusions Our results indicate that insulin concentrations of one sample measured by different methods vary greatly and should be interpreted carefully. Consideration of the immunoassay method and reliable assay-specific reference ranges are of particular importance especially in clinical cases where small changes in insulin levels can cause false classification in terms of insulin sensitivity of horses and ponies.
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Affiliation(s)
- T Warnken
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173, Hannover, Germany. .,Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.
| | - K Huber
- Institute of Animal Science, Faculty of Agricultural Sciences, University of Hohenheim, Fruwirthstraße 35, 70593, Stuttgart, Germany
| | - K Feige
- Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany
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14
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Knowles EJ, Harris PA, Elliott J, Menzies-Gow NJ. Use of the oral sugar test in ponies when performed with or without prior fasting. Equine Vet J 2016; 49:519-524. [PMID: 27381044 DOI: 10.1111/evj.12607] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 07/01/2016] [Indexed: 01/04/2023]
Abstract
BACKGROUND It is recommended that the oral sugar test (OST) for insulin dysregulation (ID) be performed after an overnight fast, but fasting is impractical in ponies kept solely at pasture. There are few data on OST repeatability and reliability in ponies. OBJECTIVES To report 1) whether OST results obtained in the morning after an overnight fast or without fasting in the afternoon (FASTING/FED) can be used interchangeably, 2) time of highest insulin concentration Tmax [insulin], repeatability and reliability of insulin response to the OST when FASTING or FED and 3) dichotomous agreement (ID/normal) within a small sample when FASTING or FED. STUDY DESIGN Method comparison study. METHODS Oral sugar tests were performed on four occasions in 10 adult native British ponies, twice FASTING and twice FED. Insulin concentrations were measured by radioimmunoassay at 0-120 min (T0,30,60,75,90,120 ). Differences between FASTING and FED results were assessed using mixed effects models. Indices of repeatability and reliability were calculated; dichotomous agreement was reported using kappa statistics. RESULTS Serum [insulin] was significantly (P≤0.05) higher at T60 -T90 with prior fasting (estimated differences [95% confidence intervals]): T60 : 23.5 μiu/ml (8.7-38.4 μiu/ml), T75 : 27.1 μiu/ml (12.3-41.8 μiu/ml), T90 : 15.1 (0.36-29.9 μiu/ml). Most frequently, Tmax [ins] occurred at T30 . At any single time point, within-subject coefficients of variation were: FASTING: 40% and FED: 31%. The 95% limits for repeatability were FASTING: 29-340%, FED: 41-240%. Test reliabilities were FASTING: 0.70 and FED: 0.67. For dichotomous interpretation similar results (kappa = 0.7) were obtained using cut-offs of [Insulin] >60 μiu/ml at T60 or T90 for FASTING and [Insulin] >51 μiu/ml at T30 or T60 for FED samples. MAIN LIMITATIONS Oral sugar tests were performed on a small number of animals on one pasture during one season (spring). CONCLUSIONS Clinicians should beware of interpreting changes in absolute OST results owing to poor repeatability. When stabling is unavailable, OSTs of ponies at pasture may yield similar dichotomous results without prior fasting.
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Affiliation(s)
- E J Knowles
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK.,Bell Equine Veterinary Clinic, Mereworth, Kent, UK
| | - P A Harris
- Equine Studies Group, WALTHAM Centre for Pet Nutrition, Waltham on the Wolds, Leicestershire, UK
| | - J Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - N J Menzies-Gow
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
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15
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Neutrophil function in healthy aged horses and horses with pituitary dysfunction. Vet Immunol Immunopathol 2015; 165:99-106. [PMID: 25962580 DOI: 10.1016/j.vetimm.2015.04.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/01/2015] [Accepted: 04/23/2015] [Indexed: 11/23/2022]
Abstract
Immunosuppression leading to opportunist bacterial infection is a well-recognized sequela of equine pituitary pars intermedia dysfunction (PPID). The mechanisms responsible for immune dysfunction in PPID however, are as of yet poorly characterized. Horses with PPID have high concentrations of hormones known to impact immune function including α-melanocyte stimulating hormone (α-MSH) and insulin. α-MSH and related melanocortins have been shown in rodents and people to impair neutrophil function by decreasing superoxide production (known as oxidative burst activity), migration and adhesion. The goal of this study was to determine if neutrophil function is impaired in horses with PPID and, if so, to determine if plasma α-MSH or insulin concentration correlated with the severity of neutrophil dysfunction. Specifically, neutrophil phagocytosis, oxidative burst activity, chemotaxis and adhesion were assessed. Results of this study indicate that horses with PPID have reduced neutrophil function, characterized by decreased oxidative burst activity and adhesion. In addition, chemotaxis was greater in healthy aged horses than in young horses or aged horses with PPID. Plasma insulin: α-MSH ratio, but not individual hormone concentration was correlated to neutrophil oxidative burst activity. In summary, neutrophil function is impaired in horses with PPID, likely due to altered hormone concentrations and may contribute to increased risk of opportunistic infections. Whether regulation of hormone concentration profiles in horses with PPID using therapeutic intervention improves neutrophil function and reduces infections needs to be explored.
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