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Huang R, Shi J, Wei R, Li J. Challenges of insulin-like growth factor-1 testing. Crit Rev Clin Lab Sci 2024; 61:388-403. [PMID: 38323343 DOI: 10.1080/10408363.2024.2306804] [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: 09/28/2023] [Revised: 12/27/2023] [Accepted: 01/15/2024] [Indexed: 02/08/2024]
Abstract
Insulin-like growth factor 1 (IGF-1), primarily synthesized in the liver, was initially discovered due to its capacity to replicate the metabolic effects of insulin. Subsequently, it emerged as a key regulator of the actions of growth hormone (GH), managing critical processes like cell proliferation, differentiation, and apoptosis. Notably, IGF-1 displays a longer half-life compared to GH, making it less susceptible to factors that may affect GH concentrations. Consequently, the measurement of IGF-1 proves to be more specific and sensitive when diagnosing conditions such as acromegaly or GH deficiency. The recognition of the existence of IGFBPs and their potential to interfere with IGF-1 immunoassays urged the implementation of various techniques to moderate this issue and provide accurate IGF-1 results. Additionally, in response to the limitations associated with IGF-1 immunoassays and the occurrence of discordant IGF-1 results, modern mass spectrometric methods were developed to facilitate the quantification of IGF-1 levels. Taking advantage of their ability to minimize the interference caused by IGF-1 variants, mass spectrometric methods offer the capacity to deliver robust, reliable, and accurate IGF-1 results, relying on the precision of mass measurements. This also enables the potential detection of pathogenic mutations through protein sequence analysis. However, despite the analytical challenges, the discordance in IGF-1 reference intervals can be attributed to a multitude of factors, potentially leading to distinct interpretations of results. The establishment of reference intervals for each assay is a demanding task, and it requires nationwide multicenter collaboration among laboratorians, clinicians, and assay manufacturers to achieve this common goal in a cost-effective and resource-efficient manner. In this comprehensive review, we examine the challenges associated with the standardization of IGF-1 measurement methods, the minimization of pre-analytical factors, and the harmonization of reference intervals. Particular emphasis will be placed on the development of IGF-1 measurement techniques using "top-down" or "bottom-up" mass spectrometric methods.
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Affiliation(s)
- Rongrong Huang
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Department of Pathology and Laboratory Medicine, Harris Health System Ben Taub Hospital, Houston, TX, USA
| | - Junyan Shi
- Department of Pathology and Laboratory Medicine, Vancouver General Hospital, Vancouver Coastal Health, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ruhan Wei
- Department of Pathology, Duke University School of Medicine, Durham, NC, USA
| | - Jieli Li
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
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2
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Tausendfreund O, Bidlingmaier M, Martini S, Müller K, Rippl M, Schilbach K, Schmidmaier R, Drey M. Growth hormone treatment in aged patients with comorbidities: A systematic review. Growth Horm IGF Res 2024; 75:101584. [PMID: 38489867 DOI: 10.1016/j.ghir.2024.101584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/05/2024] [Accepted: 03/07/2024] [Indexed: 03/17/2024]
Abstract
OBJECTIVE Hormonal substitution with growth hormone in aged patients remains a debated research topic and is rarely initiated in clinical practice. This reluctance may originate from concerns about adverse effects and the uncritical use as an anti-aging agent. Nevertheless, beneficial effects for selected patients suffering from certain acute and chronic illnesses could justify its use at an advanced age. This systematic review analyzes randomized controlled studies of GH interventions in older patients with different comorbidities to assess both, beneficial and harmful effects. DESIGN A systematic search strategy was implemented to identify relevant studies from PubMed, MEDLINE, and The Cochrane Library. INCLUSION CRITERIA participants aged over 65 years, randomized controlled trials involving human growth hormone (GH) and presence of at least one additional comorbidity independent of a flawed somatotropic axis. RESULTS The eight eligible studies encompassed various comorbidities including osteoporosis, frailty, chronic heart failure, hip fracture, amyotrophic lateral sclerosis and hemodialysis. Outcomes varied, including changes in body composition, physical performance, strength, bone mineral density, cardiovascular parameters, quality of life and housing situation. Study protocols differed greatly in GH application frequency (daily, 2nd day or 3×/week), doses (0.41 mg-2.6 mg; mean 1.3 mg per 60 kg patient) and duration (1-12 months; mean 7 months). Mild dose-related side effects were reported, alongside noticeable positive impacts particularly on body composition, functionality, and quality of life. CONCLUSION Despite limited evidence, GH treatment might offer diverse benefits with few adverse effects. Further research with IGF-I dependent indication and clear outcomes, incorporating IGF-I dependent GH titration in older adults is warranted.
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Affiliation(s)
| | | | - Sebastian Martini
- Department of Medicine IV, LMU University Hospital, LMU Munich, Germany
| | - Katharina Müller
- Department of Medicine IV, LMU University Hospital, LMU Munich, Germany
| | - Michaela Rippl
- Department of Medicine IV, LMU University Hospital, LMU Munich, Germany
| | | | - Ralf Schmidmaier
- Department of Medicine IV, LMU University Hospital, LMU Munich, Germany
| | - Michael Drey
- Department of Medicine IV, LMU University Hospital, LMU Munich, Germany
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3
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Lee JKY, Cradic K, Singh RJ, Jones J, Li J. Discordance of insulin-like growth factor-1 results and interpretation on four different platforms. Clin Chim Acta 2023; 539:130-133. [PMID: 36528048 DOI: 10.1016/j.cca.2022.11.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/09/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Inconsistent Insulin-like Growth Factor 1 (IGF-1) measurements among different platforms have been observed. In this study, we compared the IGF-1 assay on four different platforms. METHODS A total of 110 serum specimens were analyzed in this comparison study. IGF-1 was measured on the three different chemiluminescent automated immunoassay of Siemens Immulite 2000 XPi, DiaSorin Liaison XL, IDS iSYS and LC-MS/MS method. Results were compared with Weighted Deming regression. Bias was evaluated using the Bland-Altman method. RESULTS Weighted Deming regression analysis showed approximately 36 % negative variation on Immulite, compared to Liaison (Immulite = 0.64 * DiaSorin + 2.95, r2 = 0.95); 8 % negative variation on iSYS, compared to Liaison (iSYS = 0.92 * DiaSorin + 0.51, r2 = 0.97); 17 % negative variation on LC-MS/MS, compared to Liaison (LC-MS/MS = 0.83 * DiaSorin-11.23, r2 = 0.93); 34 % positive variation on LC-MS/MS compared to Immulite (LC-MS/MS = 1.34 * Immulite-21.97, r2 = 0.96); 81 % positive variation on IDS iSYS compared to Immulite (IDS iSYS = 1.81 * Immulite-117.65, r2 = 0.83). The Bland-Altman plot showed a significant negative variation of Immulite versus DiaSorin and positive variation of IDS iSYS versus Immulite. Overall agreement between different platforms was poor, which reflected systematic difference. The variation between platforms increased as IGF-1 values increased. CONCLUSIONS There are wide variations between different platforms for IGF-1 measurement. The lack of standardization in IGF-1 measurement creates a challenge for clinicians to monitor IGF-1 and treat patients with pituitary disorders, when switching from one platform to another. The potential impact of the variations in IGF-1 measurement between different platforms should be taken into consideration when managing patients.
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Affiliation(s)
- Jason K Y Lee
- Department of Clinical Laboratory, University Hospital, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Kendall Cradic
- OhioHealth Laboratory Services, Department of Pathology, OhioHealth, Columbus, OH, United States; CORPath Pathology Services, LLC, Columbus, OH, United States
| | - Ravinder J Singh
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - JoAnna Jones
- Department of Pathology, The Ohio State University Wexner Medical Center, Columbus, OH, United States.
| | - Jieli Li
- Department of Pathology, The Ohio State University Wexner Medical Center, Columbus, OH, United States.
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4
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Sienes Bailo P, Fabre Estremera M, Cuenca Alcocel J, César Márquez MÁ. Beyond the method change in clinical practice: evaluation of insulin-like growth factor I assay. ADVANCES IN LABORATORY MEDICINE 2022; 3:397-406. [PMID: 37363432 PMCID: PMC10197437 DOI: 10.1515/almed-2021-0069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 07/13/2022] [Indexed: 06/28/2023]
Abstract
Objectives Insulin-like growth factor I (IGF-I) is the preferred biomarker for diagnosing and monitoring growth-related disorders but its serum quantification presents several difficulties since different IGF-I assays still leads to different IGF-I concentrations, especially when results are either above or below the normal range. Methods We conducted a prospective study between November and December 2020 at a tertiary University Hospital with 212 serum samples to determine the analytical performance of the IGF-I assay on the Cobas e411 (Roche Diagnostics) and compare it with that of the Immulite 2000XPi (Siemens). Results In this work, we report for the first time the existence of discrepancies between IGF-I levels measured by Immulite 2000XPi and Cobas e411. Deming regression model provided a slope of 1.570 (95% CI: 1.395-1.745) and an intercept of -58.591 (95% CI: -89.151 to -28.030), with R2=0.967 and average bias of +53.061 with overestimation of IGF-I. It was found that Cobas e411 provides abnormally high IGF-I concentrations, but further studies are required to elucidate the cause of the discrepancies. Conclusions Our data can alert clinicians and laboratory professionals of this situation and avoid misinterpretation of increased IGF-I levels as a therapeutic failure rather than as a problem associated with this method change.
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Affiliation(s)
- Paula Sienes Bailo
- Department of Clinical Biochemistry, Miguel Servet University Hospital, Zaragoza, Spain; and Aragon Institute of Health Research (IIS Aragon), Zaragoza, Spain
| | - Marta Fabre Estremera
- Department of Clinical Biochemistry, Miguel Servet University Hospital, Zaragoza, Spain; and Aragon Institute of Health Research (IIS Aragon), Zaragoza, Spain
| | - José Cuenca Alcocel
- Department of Clinical Biochemistry, Miguel Servet University Hospital, Zaragoza, Spain
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5
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Neidert MC, Zeitlberger AM, Leske H, Tschopp O, Sze L, Zwimpfer C, Wiesli P, Bellut D, Bernays RL, Rushing EJ, Schmid C. Association of pre- and postoperative αKlotho levels with long-term remission after pituitary surgery for acromegaly. Sci Rep 2022; 12:14765. [PMID: 36042253 PMCID: PMC9428163 DOI: 10.1038/s41598-022-19078-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
Soluble αKlotho (sKl) is a disease-specific biomarker that is elevated in patients with acromegaly and declines after surgery for pituitary adenoma. Approximately 25% of patients do not achieve remission after surgery, therefore a risk stratification for patients early in the course of their disease may allow for the identification of patients requiring adjuvant treatment. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) have been assessed as biomarker for disease activity, however the value of sKl as a predictive biomarker of surgical success has not been evaluated yet. In this study, we measured serum biomarkers before and after transsphenoidal pituitary surgery in 55 treatment-naïve patients. Based on biochemical findings at follow-up (7–16 years), we divided patients into three groups: (A) long-term cure (defined by normal IGF-1 and random low GH (< 1 μg/l) or a suppressed GH nadir (< 0.4/μg/l) on oral glucose testing); (B) initial remission with later disease activity; (C) persistent clinical and/or biochemical disease activity. sKl levels positively related to GH, IGF-1 levels and tumor volume. Interestingly, there was a statistically significant difference in pre- and postoperative levels of sKl between the long-term cure group and the group with persistent disease activity. This study provides first evidence that sKl may serve as an additional marker for surgical success, decreasing substantially in all patients with initial clinical remission while remaining high after surgery in patients with persistent disease activity.
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Affiliation(s)
- Marian Christoph Neidert
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland. .,Department of Neurosurgery, Kantonsspital St.Gallen, Rohrschacher Strasse 95, 9007, St. Gallen, Switzerland.
| | - Anna Maria Zeitlberger
- Department of Neurosurgery, Kantonsspital St.Gallen, Rohrschacher Strasse 95, 9007, St. Gallen, Switzerland
| | - Henning Leske
- Department of Neuropathology, University Hospital Zurich, Zurich, Switzerland.,Department of Pathology, Oslo University Hospital, Oslo, Norway.,University of Oslo (UiO), Oslo, Norway
| | - Oliver Tschopp
- Division of Endocrinology and Diabetes, University Hospital Zurich, Zurich, Switzerland
| | - Lisa Sze
- Division of Endocrinology and Diabetes, Kantonsspital Winterthur, Winterthur, Switzerland
| | - Cornelia Zwimpfer
- Division of Endocrinology and Diabetes, University Hospital Zurich, Zurich, Switzerland
| | - Peter Wiesli
- Department of Internal Medicine, Kantonsspital Frauenfeld, Frauenfeld, Switzerland
| | - David Bellut
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
| | | | | | - Christoph Schmid
- Division of Endocrinology and Diabetes, University Hospital Zurich, Zurich, Switzerland
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6
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Hoffman AR, Mathison T, Andrews D, Murray K, Kelepouris N, Fleseriu M. Adult growth hormone deficiency: diagnostic and treatment journeys from the patients’ perspective. J Endocr Soc 2022; 6:bvac077. [PMID: 35673404 PMCID: PMC9165431 DOI: 10.1210/jendso/bvac077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Indexed: 11/26/2022] Open
Abstract
Adult growth hormone deficiency (AGHD) is a rare and serious condition associated with significant morbidity, including reduced quality of life, and is underdiagnosed and often missed in patients. Although the onset of AGHD can occur in either childhood or adulthood, adult-onset AGHD is more difficult to identify as it lacks the auxologic signs caused by GHD during childhood, includes symptoms that tend to be nonspecific, and lacks reliable, simple biomarker testing options. A panel of 9 patients with AGHD (3 with childhood onset; 6 with adult onset) was assembled to share their first-hand experiences, to help reveal important areas of need, increase health literacy, and to raise awareness about GHD among patients, caregivers, and healthcare practitioners. Interviews with patients yielded valuable insights from the patient perspective to supplement prior knowledge about AGHD symptomatology, biomarker testing, and treatment outcomes. Some patients described a burdensome and ineffective screening process that sometimes included many visits to different specialists, repeated rounds of biomarker testing, and, in some cases, excessive delays in AGHD diagnosis. All patients expressed frustration with insurance companies that often resist and/or delay treatment authorization and reimbursement and frequently require additional testing to verify the diagnosis, often leading to treatment gaps. These findings emphasize the necessity of more efficient identification and screening of patients with possible AGHD, better recognition by clinicians and insurance providers of the importance of sustained GH replacement therapy during adulthood, and better patient support for accessing and maintaining uninterrupted GH replacement therapy for patients with documented AGHD.
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Affiliation(s)
- Andrew R Hoffman
- Department of Medicine, Stanford University School of Medicine, Palo Alto, CA, USA
| | | | | | | | | | - Maria Fleseriu
- Pituitary Center, Department of Medicine and Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
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7
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Meshkini F, Ramezani‐Jolfaie N, Sargazi S, Clark CC, Soltani S. The effects of lycopene supplementation on
insulin‐like
growth factor‐1 and
insulin‐like
growth factor binding proteins: A systematic review of randomized controlled trials. Phytother Res 2022; 36:1633-1643. [DOI: 10.1002/ptr.7418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 01/23/2022] [Accepted: 01/29/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Fatemeh Meshkini
- Department of Biochemistry, School of medicine Shahid Sadoughi University of Medical Sciences Yazd Iran
- Student Research Committee Shahid Sadoughi University of Medical Sciences Yazd Iran
| | - Nahid Ramezani‐Jolfaie
- Department of Community Medicine, School of Medicine Hormozgan University of Medical Sciences Bandar Abbas Iran
| | - Saman Sargazi
- Cellular and Molecular Research Center, Research Institute of Cellular and Molecular Sciences in Infectious Diseases Zahedan University of Medical Sciences Zahedan Iran
| | - Cain C.T. Clark
- Faculty Research Centre for Intelligent Healthcare Coventry University Coventry UK
| | - Sepideh Soltani
- Yazd Cardiovascular Research Center, Non‐communicable Diseases Research Institute Shahid Sadoughi University of Medical Sciences Yazd Iran
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8
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Investigations into the In Vitro Metabolism of hGH and IGF-I Employing Stable-Isotope-Labelled Drugs and Monitoring Diagnostic Immonium Ions by High-Resolution/High-Accuracy Mass Spectrometry. Metabolites 2022; 12:metabo12020146. [PMID: 35208220 PMCID: PMC8877552 DOI: 10.3390/metabo12020146] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 01/28/2022] [Accepted: 01/30/2022] [Indexed: 12/04/2022] Open
Abstract
Studying the metabolism of prohibited substances is an essential element in anti-doping research in order to facilitate and improve detectability. Whilst pharmacokinetic studies on healthy volunteers are valuable, they are often difficult, not least due to safety reasons and ethical constraints, especially concerning peptidic substances, which must be administered parenterally. Hence, there is a growing need for suitable in vitro models and sophisticated analytical strategies to investigate the metabolism of protein- and peptide-derived drugs. These include human growth hormone (hGH) and its main mediator insulin-like growth factor-I (IGF-I), both prohibited in professional sports for their anabolic and lipolytic effects, while challenging in their detection, as they occur naturally in the human body.Within this study, the in vitro metabolism of hGH and IGF-I was investigated using a stable-isotope-labelled reporter ion screening strategy (IRIS). A combination of liquid chromatography, high-resolution mass spectrometry, and characteristic immonium ions generated by internal dissociation of the stable-isotope-labelled peptidic metabolites enabled the detection of specific fragments. Several degradation products for hGH and IGF-I were identified within this study. These metabolites, potentially even indicative for subcutaneous administration of the drugs, could serve as promising targets for the detection of hGH and IGF-I misuse in future anti-doping applications.
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9
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Pratt MS, van Faassen M, Remmelts N, Bischoff R, Kema IP. An antibody-free LC-MS/MS method for the quantification of intact insulin-like growth factors 1 and 2 in human plasma. Anal Bioanal Chem 2021; 413:2035-2044. [PMID: 33569646 PMCID: PMC7943504 DOI: 10.1007/s00216-021-03185-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/23/2020] [Accepted: 01/19/2021] [Indexed: 11/26/2022]
Abstract
Insulin-like growth factors 1 and 2 (IGF-1 and IGF-2) are important biomarkers in research and diagnosis of growth disorders. Quantitative analysis is performed using various ligand-binding assays or enzymatic digestion LC-MS/MS methods, whose widespread adoption is hampered by time-consuming sample preparation procedures. We present a simple and fast antibody-free LC-MS/MS method for the quantification of intact IGF-1 and IGF-2 in human plasma. The method requires 50 μL of plasma and uses fully 15N-labelled IGF-1 as internal standard. It features trifluoroethanol (TFE)-based IGF/IGF-binding protein complex dissociation and a two-step selective protein precipitation workflow, using 5% acetic acid in 80/20 acetone/acetonitrile (precipitation 1) and ice-cold ethanol (precipitation 2). Detection of intact IGF-1 and IGF-2 is performed by means of a Waters XEVO TQ-S triple quadrupole mass spectrometer in positive electrospray ionisation (ESI+) mode. Lower limits of quantification were 5.9 ng/mL for IGF-1 and 8.4 ng/mL for IGF-2. Intra-assay imprecision was below 4.5% and inter-assay imprecision was below 5.8% for both analytes. An excellent correlation was found between nominal and measured concentrations of the WHO reference standard for IGF-1. Comparison with the IDS-iSYS IGF-1 immunoassay showed good correlation (R2 > 0.97), although a significant bias was observed with the immunoassay giving substantially higher concentrations. The LC-MS/MS method described here allows for reliable and simultaneous quantification of IGF-1 and IGF-2 in plasma, without the need for enzymatic digestion. The method can be readily implemented in clinical mass spectrometry laboratories and has the potential to be adapted for the analysis of different similarly sized peptide hormones. ![]()
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Affiliation(s)
- Mark S Pratt
- Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Martijn van Faassen
- Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Noah Remmelts
- Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Rainer Bischoff
- Department of Analytical Biochemistry, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Ido P Kema
- Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
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10
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Bailes J, Soloviev M. Insulin-Like Growth Factor-1 (IGF-1) and Its Monitoring in Medical Diagnostic and in Sports. Biomolecules 2021; 11:biom11020217. [PMID: 33557137 PMCID: PMC7913862 DOI: 10.3390/biom11020217] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/29/2021] [Accepted: 01/31/2021] [Indexed: 12/16/2022] Open
Abstract
Insulin-like growth factor-1 (IGF-1) is the principal mediator of growth hormone (GH), plays a crucial role in promoting cell growth and differentiation in childhood and continues to have an anabolic effect in adults. IGF-1 is part of a wide network of growth factors, receptors and binding proteins involved in mediating cellular proliferation, differentiation and apoptosis. Bioavailability of IGF-1 is affected by insulin-like growth factor binding proteins (IGFBPs) which bind IGF-1 in circulation with an affinity equal to or greater than that of the IGF-1 receptor (IGF-1R). The six IGFBPs serve as carrier proteins and bind approximately 98% of all circulating IGF-1. Other proteins known to bind IGF-1 include ten IGFBP-related proteins (IGFBP-rPs), albeit with lower affinities than the IGFBPs. IGF-1 expression levels vary in a number of clinical conditions suggesting it has the potential to provide crucial information as to the state of an individual’s health. IGF-1 is also a popular doping agent in sport and has featured in many high-profile doping cases in recent years. However, the existence of IGFBPs significantly reduces the levels of immunoreactive IGF-1 in samples, requiring multiple pre-treatment steps that reduce reproducibility and complicates interpretation of IGF-1 assay results. Here we provide an overview of the IGF network of growth factors, their receptors and the entirety of the extended family of IGFBPs, IGFBP-rPs, E peptides as well as recombinant IGF-1 and their derivatives. We also discuss issues related to the detection and quantification of bioavailable IGF-1.
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11
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Giustina A, Barkhoudarian G, Beckers A, Ben-Shlomo A, Biermasz N, Biller B, Boguszewski C, Bolanowski M, Bollerslev J, Bonert V, Bronstein MD, Buchfelder M, Casanueva F, Chanson P, Clemmons D, Fleseriu M, Formenti AM, Freda P, Gadelha M, Geer E, Gurnell M, Heaney AP, Ho KKY, Ioachimescu AG, Lamberts S, Laws E, Losa M, Maffei P, Mamelak A, Mercado M, Molitch M, Mortini P, Pereira AM, Petersenn S, Post K, Puig-Domingo M, Salvatori R, Samson SL, Shimon I, Strasburger C, Swearingen B, Trainer P, Vance ML, Wass J, Wierman ME, Yuen KCJ, Zatelli MC, Melmed S. Multidisciplinary management of acromegaly: A consensus. Rev Endocr Metab Disord 2020; 21:667-678. [PMID: 32914330 PMCID: PMC7942783 DOI: 10.1007/s11154-020-09588-z] [Citation(s) in RCA: 176] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/01/2020] [Indexed: 12/18/2022]
Abstract
The 13th Acromegaly Consensus Conference was held in November 2019 in Fort Lauderdale, Florida, and comprised acromegaly experts including endocrinologists and neurosurgeons who considered optimal approaches for multidisciplinary acromegaly management. Focused discussions reviewed techniques, results, and side effects of surgery, radiotherapy, and medical therapy, and how advances in technology and novel techniques have changed the way these modalities are used alone or in combination. Effects of treatment on patient outcomes were considered, along with strategies for optimizing and personalizing therapeutic approaches. Expert consensus recommendations emphasize how best to implement available treatment options as part of a multidisciplinary approach at Pituitary Tumor Centers of Excellence.
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Affiliation(s)
- Andrea Giustina
- Institute of Endocrine and Metabolic Sciences, San Raffaele Vita-Salute University, IRCCS San Raffaele Hospital, Ospedale San Raffaele, Via Olgettina, 58, 20132, Milan, Italy.
| | - Garni Barkhoudarian
- Pacific Pituitary Disorders Center, Pacific Neuroscience Institute, Santa Monica, CA, USA
| | - Albert Beckers
- Department of Endocrinology, University of Liège, Liège, Belgium
| | - Anat Ben-Shlomo
- Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Nienke Biermasz
- Division of Endocrinology and Center for Endocrine Tumors, Department of Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Beverly Biller
- Neuroendocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Cesar Boguszewski
- SEMPR, Endocrine Division, Department of Internal Medicine, Federal University of Parana, Curitiba, Brazil
| | - Marek Bolanowski
- Department of Endocrinology, Diabetes and Isotope Therapy, Wroclaw Medical University, Wroclaw, Poland
| | - Jens Bollerslev
- Section of Specialized Endocrinology, Department of Endocrinology, University of Oslo, Oslo, Norway
| | - Vivien Bonert
- Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Marcello D Bronstein
- Neuroendocrine Unit, Division of Endocrinology and Metabolism, Hospital das Clinicas, University of Sao Paulo, Sao Paulo, Brazil
| | - Michael Buchfelder
- Department of Neurosurgery, University Hospital Erlangen, Erlangen, Germany
| | - Felipe Casanueva
- Division of Endocrinology, Santiago de Compostela University and Ciber OBN, Santiago de Compostela, Spain
| | - Philippe Chanson
- Centre de Référence des Maladies Rares de l'Hypophyse and Université Paris-Saclay, Univ. Paris-Sud, Inserm, Signalisation Hormonale, Physiopathologie Endocrinienne et Métabolique, Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Service d'Endocrinologie et des Maladies de la Reproduction, Le Kremlin-Bicêtre, Paris, France
| | - David Clemmons
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Maria Fleseriu
- Departments of Medicine and Neurological Surgery, Pituitary Center, Oregon Health & Science University, Portland, Oregon, USA
| | - Anna Maria Formenti
- Institute of Endocrine and Metabolic Sciences, San Raffaele Vita-Salute University, IRCCS San Raffaele Hospital, Ospedale San Raffaele, Via Olgettina, 58, 20132, Milan, Italy
| | - Pamela Freda
- Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Monica Gadelha
- Neuroendocrinology Research Center/Endocrinology Section, Medical School and Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Eliza Geer
- Multidisciplinary Pituitary and Skull Base Tumor Center, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Mark Gurnell
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge and NIHR Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK
| | - Anthony P Heaney
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Ken K Y Ho
- The Garvan Institute of Medical Research, St. Vincent's Hospital, University of New South Wales, Sydney, Australia
| | - Adriana G Ioachimescu
- Department of Neurosurgery and Medicine, Division of Endocrinology, Metabolism and Lipids, Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, USA
| | | | - Edward Laws
- Pituitary/Neuroendocrine Center, Brigham & Women's Hospital, Boston, MA, USA
| | - Marco Losa
- Department of Neurosurgery, San Raffaele University Health Institute Milan, Milan, Italy
| | - Pietro Maffei
- Department of Medicine, Padua University Hospital, Padua, Italy
| | - Adam Mamelak
- Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Moises Mercado
- Medical Research Unit in Endcrine Diseases, Hospital de Especialidades, Centro Médico Nacional, Siglo XXI, IMSS, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Mark Molitch
- Division of Endocrinology, Metabolism & Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Pietro Mortini
- Department of Neurosurgery, San Raffaele University Health Institute Milan, Milan, Italy
| | - Alberto M Pereira
- Division of Endocrinology and Center for Endocrine Tumors, Department of Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Kalmon Post
- Department of Neurosurgery, Medicine, Mount Sinai Health System, New York, NY, USA
| | - Manuel Puig-Domingo
- Germans Trias i Pujol Research Institute, Universitat Autònoma de Barcelona, Badalona, Barcelona, Spain
| | - Roberto Salvatori
- Division of Endocrinology, Diabetes, and Metabolism and Pituitary Center, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Susan L Samson
- Departments of Medicine and Neurosurgery, Baylor St. Luke's Pituitary Center, Baylor College of Medicine, Houson, TX, USA
| | - Ilan Shimon
- Endocrine Institute, Rabin Medical Center, Beilinson Hospital, Petah-Tikva, Israel
| | - Christian Strasburger
- Department of Medicine for Endocrinology, Diabetes and Nutritional Medicine, Charité Universitätsmedizin, Berlin, Germany
| | - Brooke Swearingen
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, USA
| | - Peter Trainer
- Department of Endocrinology, The Christie NHS Foundation Trust, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Mary L Vance
- Department of Medicine, University of Virginia, Charlottesville, VA, USA
| | - John Wass
- Department of Endocrinology, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, UK
| | - Margaret E Wierman
- Pituitary, Adrenal and Neuroendocrine Tumor Program, Department of Medicine, University of Colorado Anschutz Medical Center, Aurora, CO, USA
| | - Kevin C J Yuen
- Barrow Pituitary Center and Neuroendocrinology Clinic, Barrow Neurological Institute, University of Arizona College of Medicine, Creighton School of Medicine, Phoenix, AZ, USA
| | - Maria Chiara Zatelli
- Section of Endocrinology & Internal Medicine, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Shlomo Melmed
- Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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12
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A high-throughput assay for the quantification of intact Insulin-like Growth Factor I in human serum using online SPE-LC-HRMS. Clin Chim Acta 2020; 510:391-399. [DOI: 10.1016/j.cca.2020.07.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/27/2020] [Accepted: 07/27/2020] [Indexed: 02/04/2023]
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13
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Corica G, Ceraudo M, Campana C, Nista F, Cocchiara F, Boschetti M, Zona G, Criminelli D, Ferone D, Gatto F. Octreotide-Resistant Acromegaly: Challenges and Solutions. Ther Clin Risk Manag 2020; 16:379-391. [PMID: 32440136 PMCID: PMC7211320 DOI: 10.2147/tcrm.s183360] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 03/10/2020] [Indexed: 12/14/2022] Open
Abstract
Acromegaly is a rare and severe disease caused by an increased and autonomous secretion of growth hormone (GH), thus resulting in high circulating levels of insulin-like growth factor 1 (IGF-1). Comorbidities and mortality rate are closely related to the disease duration. However, in most cases achieving biochemical control means reducing or even normalizing mortality and restoring normal life expectancy. Current treatment for acromegaly includes neurosurgery, radiotherapy and medical therapy. Transsphenoidal surgery often represents the recommended first-line treatment. First-generation somatostatin receptor ligands (SRLs) are the drug of choice in patients with persistent disease after surgery and are suggested as first-line treatment for those ineligible for surgery. However, only about half of patients treated with octreotide (or lanreotide) achieve biochemical control. Other available drugs approved for clinical use are the second-generation SRL pasireotide, the dopamine agonist cabergoline, and the GH-receptor antagonist pegvisomant. In the present paper, we revised the current literature about the management of acromegaly, aiming to highlight the most relevant and recent therapeutic strategies proposed for patients resistant to first-line medical therapy. Furthermore, we discussed the potential molecular mechanisms involved in the variable response to first-generation SRLs. Due to the availability of different medical therapies, the choice for the most appropriate drug can be currently based also on the peculiar clinical characteristics of each patient.
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Affiliation(s)
- Giuliana Corica
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Endocrinology Unit, Department of Internal Medicine and Medical Specialties (DIMI) and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Marco Ceraudo
- Neurosurgery Unit, Department of Neurosciences (DINOGMI), IRCCS Ospedale Policlinico San Martino, University of Genoa, Genoa, Italy
| | - Claudia Campana
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Endocrinology Unit, Department of Internal Medicine and Medical Specialties (DIMI) and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Federica Nista
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Endocrinology Unit, Department of Internal Medicine and Medical Specialties (DIMI) and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Francesco Cocchiara
- Endocrinology Unit, Department of Internal Medicine and Medical Specialties (DIMI) and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Mara Boschetti
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Endocrinology Unit, Department of Internal Medicine and Medical Specialties (DIMI) and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Gianluigi Zona
- Neurosurgery Unit, Department of Neurosciences (DINOGMI), IRCCS Ospedale Policlinico San Martino, University of Genoa, Genoa, Italy
| | - Diego Criminelli
- Neurosurgery Unit, Department of Neurosciences (DINOGMI), IRCCS Ospedale Policlinico San Martino, University of Genoa, Genoa, Italy
| | - Diego Ferone
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Endocrinology Unit, Department of Internal Medicine and Medical Specialties (DIMI) and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Federico Gatto
- Endocrinology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
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14
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Janssen JAMJL, Varewijck AJ, Brugts MP. The insulin-like growth factor-I receptor stimulating activity (IRSA) in health and disease. Growth Horm IGF Res 2019; 48-49:16-28. [PMID: 31493625 DOI: 10.1016/j.ghir.2019.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 07/26/2019] [Accepted: 08/19/2019] [Indexed: 10/26/2022]
Abstract
Determination of true IGF-I bioactivity in serum and other biological fluids is still a substantial challenge. The IGF-IR Kinase Receptor Activation assay (IGF-IR KIRA assay) is a novel tool to asses IGF-IR stimulating activity (IRSA) and has opened a new era in studying the IGF system. In this paper we discuss many studies showing that measuring IRSA by the IGF-IR KIRA assay often provides fundamentally different information about the IGF system than the commonly used total IGF-I immunoassays. With the IGF-IR KIRA assay phosphorylation of tyrosine residues of the IGF-IR is used as read out to quantify IRSA in unknown (serum) samples. The IGF-IR KIRA assay gives information about net overall effects of circulating IGF-I, IGF-II, IGFBPs and IGFBP-proteases on IGF-IR activation and seems especially superior to immunoreactive total IGF-I in monitoring therapeutic interventions. Although the IRSA as measured by the IGF-IR KIRA assay probably more closely reflects true bioactive IGF-I than measurements of total IGF-I in serum, the IGF-IR KIRA assay in its current form does not give information about all the post-receptor intracellular events mediated by the IGF-IR. Interestingly, in several conditions in health and disease IRSA measured by the IGF-IR KIRA assay is considerably higher in interstitial fluid and ascites than in serum. This suggests that both the paracrine (local) and endocrine (circulating) IRSA should be measured to get a complete picture about the role of the IGF system in health and disease.
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Affiliation(s)
- Joseph A M J L Janssen
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, Rotterdam, the Netherlands.
| | - Aimee J Varewijck
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, Rotterdam, the Netherlands
| | - Michael P Brugts
- Department of Internal Medicine, Ikazia Hospital, Rotterdam, the Netherlands
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15
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Granada ML. Biochemical following-up of treated acromegaly. Limitations of the current determinations of IGF-I and perspective. MINERVA ENDOCRINOL 2019; 44:143-158. [DOI: 10.23736/s0391-1977.18.02922-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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16
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17
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Abstract
Human chorionic gonadotropin (HCG) is a glycoprotein secreted by placental trophoblast cells in pregnancy. HCG is a heterodimer composed of two different α- and β-subunits, with the latter being unique to HCG. As well as being the most important diagnostic markers for pregnancy, HCG is also a tumor marker, therefore, quantitative detection of HCG is of great value. Numerous advanced technologies have been developed for HCG concentration detection including electrochemical immunoassay, chemiluminescent immunoassay, fluorescence immunoassay, resonance scattering spectrometry, atomic emission spectrometry, radioimmunoassay, MS and so on. Some have pursued simple and easy operation, while others have emphasized on accuracy and applications in clinical medicine. This review provides a comprehensive summary of various methods of detecting HCG.
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18
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Abstract
The advent of mass spectrometry into the clinical laboratory has led to an improvement in clinical management of several endocrine diseases. Liquid chromatography tandem mass spectrometry found some of its first clinical applications in the diagnosis of inborn errors of metabolism, in quantitative steroid analysis, and in drug analysis laboratories. Mass spectrometry assays offer analytical sensitivity and specificity that is superior to immunoassays for many analytes. This article highlights several areas of clinical endocrinology that have witnessed the use of liquid chromatography tandem mass spectrometry to improve clinical outcomes.
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Affiliation(s)
- Siva S Ketha
- Department of Cardiovascular Diseases, Mayo Clinic, 4500 San Pablo Road South, Jacksonville, FL 32224, USA
| | - Ravinder J Singh
- Department of Pathology and Laboratory Medicine, Mayo Clinic, 200 2nd Street, Rochester, MN, 55905, USA
| | - Hemamalini Ketha
- Department of Pathology, University Hospital, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Room 2F432, Ann Arbor, MI, 48109, USA.
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Mavromati M, Kuhn E, Agostini H, Brailly-Tabard S, Massart C, Piketty ML, Arnoux A, Young J, Souberbielle JC, Chanson P. Classification of Patients With GH Disorders May Vary According to the IGF-I Assay. J Clin Endocrinol Metab 2017; 102:2844-2852. [PMID: 28505364 DOI: 10.1210/jc.2017-00202] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 05/08/2017] [Indexed: 11/19/2022]
Abstract
CONTEXT Insulinlike growth factor I (IGF-I) measurement is essential for the diagnosis and management of growth hormone (GH) disorders. However, patient classification may vary substantially according to the assay technique. OBJECTIVE We compared individual patient data and classifications obtained with six different IGF-I assay kits in a group of patients with various GH disorders. DESIGN In this cross-sectional study, we measured IGF-I with six immunoassays in 102 patients with active or treated acromegaly or GH deficiency. IGF-I normative data previously established for the same six assay kits were used to classify the patients (high, low, or normal IGF-I levels), using both raw data and standard deviation scores (SDSs). Pairwise concordance between assays was assessed with Bland-Altman plots and with the percentage of observed agreement and the weighted κ coefficient for categorized IGF-I SDS. RESULTS We observed marked variability both across each individual's IGF-I raw data and across IGF-I SDS values obtained with each of the six immunoassays. Pairwise concordance between assay values, as assessed with the weighted κ coefficient, ranged from 0.50 (moderate) to 0.81 (excellent). CONCLUSION Even when using normative data obtained in the same large population of healthy subjects and when using calculated IGF-I SDSs, agreement among IGF-I assay methods is only moderate to good. Differences in assay performance must be taken into account when evaluating and monitoring patients with GH disorders. This argues for the use of the same IGF-I assay for a given patient throughout follow-up.
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Affiliation(s)
- Maria Mavromati
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Rares de l'Hypophyse, F94275 Le Kremlin-Bicêtre, France
| | - Emmanuelle Kuhn
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Rares de l'Hypophyse, F94275 Le Kremlin-Bicêtre, France
- Inserm 1185, Fac Med Paris Sud, Université Paris-Saclay, F94276 Le Kremlin-Bicêtre, France
| | - Hélène Agostini
- Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Unité de Recherche Clinique, F94275 Le Kremlin-Bicêtre, France
| | - Sylvie Brailly-Tabard
- Inserm 1185, Fac Med Paris Sud, Université Paris-Saclay, F94276 Le Kremlin-Bicêtre, France
- Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, F94275 Le Kremlin-Bicêtre, France
| | - Catherine Massart
- Laboratoire d'Hormonologie, Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, F29000 Rennes, France
| | - Marie-Liesse Piketty
- Service des Explorations Fonctionnelles, Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, F75015 Paris, France
| | - Armelle Arnoux
- Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Unité de Recherche Clinique, F94275 Le Kremlin-Bicêtre, France
| | - Jacques Young
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Rares de l'Hypophyse, F94275 Le Kremlin-Bicêtre, France
- Inserm 1185, Fac Med Paris Sud, Université Paris-Saclay, F94276 Le Kremlin-Bicêtre, France
| | - Jean-Claude Souberbielle
- Service des Explorations Fonctionnelles, Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, F75015 Paris, France
| | - Philippe Chanson
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Rares de l'Hypophyse, F94275 Le Kremlin-Bicêtre, France
- Inserm 1185, Fac Med Paris Sud, Université Paris-Saclay, F94276 Le Kremlin-Bicêtre, France
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20
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Paragliola RM, Corsello SM, Salvatori R. Somatostatin receptor ligands in acromegaly: clinical response and factors predicting resistance. Pituitary 2017; 20:109-115. [PMID: 27778296 DOI: 10.1007/s11102-016-0768-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Somatostatin (SST) receptor ligands (SRL), in particular those of first generation (Octreotide and Lanreotide), are widely used in medical treatment of acromegaly, but they assure biochemical control of disease (and the possibility of an improvement of clinical symptoms and tumor shrinkage), only in a subset of patients. DISCUSSION The mechanisms underlying the so called "SRL resistance" are various and involve in particular SST receptor expression and molecular pathways of signal transduction. Different predictors of SRL response have been reported, including clinical and biochemical features (gender, age, growth hormone and insulin-like growth factor-I levels at diagnosis), and tumor characteristic (both at preoperative magnetic resonance imaging study and histopathology) as well as expression of SST receptors. In some cases, only a "partial resistance" to SST can be detected, probably due to the presence of other impaired molecular mechanisms involved in signal transduction, which compromise specific pathways and not others. This may explain some cases of dissociated response between biochemical control and tumor shrinkage.
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Affiliation(s)
- Rosa Maria Paragliola
- Unit of Endocrinology, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli 8, 00168, Rome, Italy
| | - Salvatore Maria Corsello
- Unit of Endocrinology, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli 8, 00168, Rome, Italy
| | - Roberto Salvatori
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Pituitary Center, Johns Hopkins University School of Medicine, 1830 East Monument Street Suite #333, Baltimore, MD, 21287, USA.
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Abstract
Measurements of human growth hormone (GH) and insulin-like growth-factor I (IGF-I) are cornerstones in the diagnosis of acromegaly. Both hormones are also used as biochemical markers in the evaluation of disease activity during treatment. Management of acromegaly is particularly challenging in cases where discordant information is obtained from measurement of GH concentrations following oral glucose load and from measurement of IGF-I. While in some patients biological factors can explain the discrepancy, in many cases issues with the analytical methods seem to be responsible. Assays used by endocrine laboratories to determine concentrations of GH and IGF-I underwent significant changes during the last decades. While generally leading to more sensitive and reproducible methods, these changes also had considerable impact on absolute concentrations measured. This must be reflected by updated decision limits, cut-offs and reference intervals. Since different commercially available assays do not agree very well, method specific interpretation of GH and IGF-I concentrations is required. This complexity in the interpretation of hormone concentrations is not always appropriately reflected in laboratory reports, but also not in clinical guidelines reporting decision limits not related to a specific analytical method. The present review provides an overview about methodological and biological variables affecting the biochemical assessment of acromegaly in diagnosis and follow up.
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Affiliation(s)
- Katharina Schilbach
- Clinical Endocrinology and Endocrine Laboratory, Medizinische Klinik und Poliklinik IV, Klinikum der Ludwig-Maximilians-Universität (LMU), Ziemssenstr. 1, 80336, Munich, Germany
| | - Christian J Strasburger
- Department of Endocrinology and Metabolic Diseases, Campus Charité Mitte, Charité Universitätsmedizin, Charitéplatz 1, 10117, Berlin, Germany
| | - Martin Bidlingmaier
- Endocrine Laboratory, Endocrine Research Unit, Medizinische Klinik und Poliklinik IV, Klinikum der Ludwig-Maximilians-Universität (LMU), Ziemssenstr. 1, 80336, Munich, Germany.
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22
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Chinoy A, Murray PG. Diagnosis of growth hormone deficiency in the paediatric and transitional age. Best Pract Res Clin Endocrinol Metab 2016; 30:737-747. [PMID: 27974187 DOI: 10.1016/j.beem.2016.11.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Growth hormone deficiency is a rare cause of childhood short stature, but one for which treatment exists in the form of recombinant human growth hormone. A diagnosis of growth hormone deficiency is made based on auxology, biochemistry and imaging. Although no diagnostic gold standard exists, growth hormone provocation tests are considered the mainstay of diagnostic investigations. However, these must be interpreted with caution in view of issues with variability and reproducibility, as well as the limited evidence-base for cut-off values used to distinguish growth hormone deficient and non-growth hormone deficient subjects. In addition, nutritional and pubertal status can affect results, with no consensus on the role of priming with sex steroid hormones. Difficulties with assays exist both for growth hormone as well as insulin-like growth factor-1. Pituitary magnetic resonance imaging is a useful diagnostic, and possibly prognostic, aid. Although genetic testing is not routine, the discovery of more relevant mutations makes it an increasingly important investigation. Children with growth hormone deficiency are retested biochemically on completion of growth, to assess whether they remain so into adulthood.
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Affiliation(s)
- A Chinoy
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester, UK
| | - P G Murray
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester, UK; Centre for Paediatrics and Child Health, Institute of Human Development, University of Manchester, Manchester, UK.
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Mesaros C, Blair IA. Mass spectrometry-based approaches to targeted quantitative proteomics in cardiovascular disease. Clin Proteomics 2016; 13:20. [PMID: 27713681 PMCID: PMC5050566 DOI: 10.1186/s12014-016-9121-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 07/19/2016] [Indexed: 01/11/2023] Open
Abstract
Mass spectrometry-based proteomics methodology has become an important tool in elucidating some of the underlying mechanisms involved in cardiovascular disease. The present review provides details on selected important protein targets where highly selective and specific mass spectrometry-based approaches have led to important new findings and provided new mechanistic information. The role of six proteins involved in the etiology of cardiovascular disease (acetylated platelet cyclooxygenase-1, serum apolipoprotein A1, apolipoprotein C-III, serum C-reactive protein, serum high mobility group box-1 protein, insulin-like growth factor I) and their quantification has been discussed. There are an increasing number of examples where highly selective mass spectrometry-based quantification has provided new important data that could not be obtained with less labor intensive and cheaper immunoassay-based procedures. It is anticipated that these findings will lead to significant advances in a number of important issues related to the role of specific proteins in cardiovascular disease. The availability of a new generation of high-resolution high-sensitivity mass spectrometers will greatly facilitate these studies so that in the future it will be possible to analyze serum proteins of relevance to cardiovascular disease with levels of specificity and/or sensitivity that cannot be attained by immunoassay-based procedures.
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Affiliation(s)
- Clementina Mesaros
- Penn SRP Center and Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104 USA ; BluePen Biomarkers, 3401 Grays Ferry Avenue, Philadelphia, PA 19146-2799 USA
| | - Ian A Blair
- Penn SRP Center and Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104 USA ; BluePen Biomarkers, 3401 Grays Ferry Avenue, Philadelphia, PA 19146-2799 USA
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24
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Chanson P, Arnoux A, Mavromati M, Brailly-Tabard S, Massart C, Young J, Piketty ML, Souberbielle JC. Reference Values for IGF-I Serum Concentrations: Comparison of Six Immunoassays. J Clin Endocrinol Metab 2016; 101:3450-8. [PMID: 27167056 PMCID: PMC5054194 DOI: 10.1210/jc.2016-1257] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CONTEXT Measurement of IGF-I is essential for diagnosis and management of patients with disorders affecting the somatotropic axis. However, even when IGF-I kit manufacturers follow recent consensus guidelines, different kits can give very different results for a given sample. OBJECTIVES We sought to establish normative data for six IGF-I assay kits based on a large random sample of the French general adult population. SUBJECTS AND METHODS In a cross-sectional multicenter cohort study, we measured IGF-I in 911 healthy adults (18-90 years) with six immunoassays (iSYS, LIAISON XL, IMMULITE, IGFI RIACT, Mediagnost ELISA, and Mediagnost RIA). Pairwise concordance between assays was assessed with Bland-Altman plots for both IGF-1 raw data and standard deviation scores (SDS), as well as with the percentage of observed agreement and the weighted Kappa coefficient for categorized IGF-I SDS. RESULTS Normative data included the range of values (2.5-97.5 percentiles) given by the six IGF-I assays according to age group and sex. A formula for SDS calculation is provided. Although the lower limits of the reference intervals of the six assays were similar, the upper limits varied markedly. Pairwise concordances were moderate to good (0.38-0.70). CONCLUSION Despite being obtained in the same healthy population, the reference intervals of the six commercial IGF-1 assay kits showed noteworthy differences. Agreement between methods was moderate to good.
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Affiliation(s)
- Philippe Chanson
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
| | - Armelle Arnoux
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
| | - Maria Mavromati
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
| | - Sylvie Brailly-Tabard
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
| | - Catherine Massart
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
| | - Jacques Young
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
| | - Marie-Liesse Piketty
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
| | - Jean-Claude Souberbielle
- Service d'Endocrinologie et des Maladies de la Reproduction and Centre de Référence des Maladies Endocriniennes Rares de la Croissance (P.C., M.M., J.Y.), Unité de Recherche Clinique (A.A.), and Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie (S.B.T.), Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Le Kremlin-Bicêtre, F94275, France; Inserm 1185 (P.C., S.B.T., J.Y.), Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, F-94276, France; and Laboratoire d'Hormonologie (C.M.), Centre Hospitalier Universitaire de Rennes, Centre d'Investigation Clinique Plurithématique, Inserm 1414, Hôpital Pontchaillou, Rennes, F29000, France; Service des Explorations Fonctionnelles (M-L.P., J.-C.S.), Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Paris, F75015, France
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Prencipe N, Floriani I, Guaraldi F, Di Giacomo SV, Cannavo S, Arnaldi G, Berton A, Torri V, Spinello M, Arvat E, Ghigo E, Grottoli S. ACROSCORE: a new and simple tool for the diagnosis of acromegaly, a rare and underdiagnosed disease. Clin Endocrinol (Oxf) 2016; 84:380-5. [PMID: 26433136 DOI: 10.1111/cen.12959] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/18/2015] [Accepted: 09/21/2015] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Acromegaly, a disease caused by GH/IGF-I hypersecretion, is associated with a high mortality rate; early recognition is therefore necessary to ensure successful treatment and to avoid comorbidities. We have created a symptom/sign scoring tool (ACROSCORE) for physicians to use to identify acromegaly. DESIGN To compare cases of acromegaly diagnosed between 1990 and 2014 against a control group affected by non-GH-secreting pituitary tumours to identify symptoms and signs that are most discriminative for acromegaly. PATIENTS Confirmed acromegaly patients and patients affected by non-GH-secreting pituitary tumours. MEASUREMENTS In all patients, signs, symptoms and comorbidities were recorded from medical records and collected using a specifically designed questionnaire. RESULTS A total of 194 acromegaly patients [115 women; mean (SD) age 47·2 (14·2) years] and 243 patients affected by non-GH-secreting pituitary tumours [131 women; mean (SD) age 45·8 (15·8) years] were included. A strong association was observed for type 2/secondary diabetes [odds ratio (OR) 3·7], hyperhidrosis (OR 6·1), thyroid hyperplasia (OR 13·9), colorectal polyps (OR 10·4), spaced teeth (OR 25·4) and carpal tunnel syndrome (OR 4·3). Based on this information, a multivariable logistic model was built and a 14-point scoring system developed. A score of 0 excludes the risk of acromegaly [positive predictive value (PV(+)) = 0·6%]; scores 1-5 comprise a grey area; scores >5 indicate that a diagnosis of acromegaly cannot be excluded (PV(+) = 46·1%). CONCLUSIONS Once validated in independent studies, ACROSCORE may represent a new tool for the clinical screening of acromegaly that can be used by general practitioners and nonendocrinology specialists.
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Affiliation(s)
- Nunzia Prencipe
- Department of Medical Science, Division of Endocrinology, Diabetology and Metabolism, Città della Salute e della Scienza di Torino, University of Torino, Torino, Italy
| | - Irene Floriani
- Department of Oncology, IRCCS Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy
| | - Federica Guaraldi
- Department of Medical Science, Division of Endocrinology, Diabetology and Metabolism, Città della Salute e della Scienza di Torino, University of Torino, Torino, Italy
| | - Stellina V Di Giacomo
- Department of Medical Science, Division of Endocrinology, Diabetology and Metabolism, Città della Salute e della Scienza di Torino, University of Torino, Torino, Italy
| | - Salvatore Cannavo
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Giorgio Arnaldi
- Endocrinology Division, Department of Clinical and Molecular Sciences, Politecnica delle Marche University, Ancona, Italy
| | - Alessandro Berton
- Department of Medical Science, Division of Endocrinology, Diabetology and Metabolism, Città della Salute e della Scienza di Torino, University of Torino, Torino, Italy
| | - Valter Torri
- Department of Oncology, IRCCS Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy
| | | | - Emanuela Arvat
- Department of Medical Science, Division of Oncological Endocrinology, Città della Salute e della Scienza di Torino, University of Torino, Torino, Italy
| | - Ezio Ghigo
- Department of Medical Science, Division of Endocrinology, Diabetology and Metabolism, Città della Salute e della Scienza di Torino, University of Torino, Torino, Italy
| | - Silvia Grottoli
- Department of Medical Science, Division of Endocrinology, Diabetology and Metabolism, Città della Salute e della Scienza di Torino, University of Torino, Torino, Italy
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Association between Serum IGF-I levels and Postoperative Delirium in Elderly Subjects Undergoing Elective Knee Arthroplasty. Sci Rep 2016; 6:20736. [PMID: 26846868 PMCID: PMC4742946 DOI: 10.1038/srep20736] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 01/07/2016] [Indexed: 11/24/2022] Open
Abstract
Evidence is mixed for an association between serum insulin-like growth factor-I (IGF-I) levels and postoperative delirium (POD). The current study assessed preoperative serum IGF-I levels as a predictor of incident delirium in non-demented elderly elective knee arthroplasty patients. Preoperative serum levels of total IGF-I were measured using a commercially available Human IGF-I ELISA kit. POD incidence and severity were determined using DSM-IV criteria and the Delirium Rating Scale-Revised-98 (DRS-R98), respectively. Median IGF-I levels in delirious (62.6 ng/ml) and non-delirious groups (65.9 ng/ml) were not significantly different (p = 0.141). The ratio (95% CI) of geometric means, D/ND, was 0.86 (0.70, 1.06). The Hodges-Lehmann median difference estimate was 7.23 ng/mL with 95% confidence interval (−2.32, 19.9). In multivariate logistic regression analysis IGF-I level was not a significant predictor of incident POD after correcting for medical comorbidities. IGF-I levels did not correlate with DRS-R98 scores for delirium severity. In conclusion, we report no evidence of association between serum IGF-I levels and incidence of POD, although the sample size was inadequate for a conclusive study. Further efforts to investigate IGF-I as a delirium risk factor in elderly should address comorbidities and confounders that influence IGF-I levels.
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Ketha H, Singh RJ. Quantitation of Insulin-Like Growth Factor 1 in Serum by Liquid Chromatography High Resolution Accurate-Mass Mass Spectrometry. Methods Mol Biol 2016; 1378:131-7. [PMID: 26602125 DOI: 10.1007/978-1-4939-3182-8_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Insulin-like growth factor 1 (IGF-1) is a 70 amino acid peptide hormone which acts as the principal mediator of the effects of growth hormone (GH). Due to a wide variability in circulating concentration of GH, IGF-1 quantitation is the first step in the diagnosis of GH excess or deficiency. Majority (>95 %) of IGF-1 circulates as a ternary complex along with its principle binding protein insulin-like growth factor 1 binding protein 3 (IGFBP-3) and acid labile subunit. The assay design approach for IGF-1 quantitation has to include a step to dissociate IGF-1 from its ternary complex. Several commercial assays employ a buffer containing acidified ethanol to achieve this. Despite several modifications, commercially available immunoassays have been shown to have challenges with interference from IGFBP-3. Additionally, inter-method comparison between IGF-1 immunoassays has been shown to be suboptimal. Mass spectrometry has been utilized for quantitation of IGF-1. In this chapter a liquid chromatography high resolution accurate-mass mass spectrometry (LC-HRAMS) based method for IGF-1 quantitation has been described.
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Affiliation(s)
- Hemamalini Ketha
- Departement of Pathology, University of Michigan Health System, Ann Arbor, MN, 48109-5054, USA
| | - Ravinder J Singh
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 2nd Street SW, Rochester, MN, 55905, USA.
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Guitelman M, Smithuis F, Garcia Basavilbaso N, Aranda C, Fabre B, Oneto A. Reference ranges for an automated chemiluminescent assay for serum insulin-like growth factor I (IGF-I) in a large population of healthy adults from Buenos Aires. J Endocrinol Invest 2015; 38:951-6. [PMID: 25740070 DOI: 10.1007/s40618-015-0265-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/19/2015] [Indexed: 11/30/2022]
Abstract
PURPOSE Insulin-like growth factor I (IGF-I) represents an essential tool in the diagnostic work-up and in the monitoring of treatment efficacy for somatotrophic axis disorders both in children and adults. A large number of factors including, but not limited to, age, sex and weight as well as analytical variables influence IGF-I serum levels; therefore, reliable normative data are essential for a correct interpretation of results. The aim of the present study was to establish reference range values for serum IGF-I, in a large population of healthy adults from Buenos Aires city. METHODS The study included serum samples from 1044 healthy subjects aged 21-87 years (423 females and 621 males) divided into groups by sex at 5-year intervals from 21 to >75 years. Serum IGF-I concentrations were determined by a fully automated two-site, solid-phase, enzyme-labeled chemiluminescent immunometric assay (Immulite 2000, Siemens Healthcare Diagnostics). IGF-BP interferences are circumvented by blocking IGF-BP binding sites with excess IGF-II in the on-board predilution step. RESULTS Results show the age dependence of circulating IGF-I levels, with a smooth and steady decrease in levels with age. No sex differences were found in subjects >26 years; however, in the group aged 21-25 years, IGF-I levels were significantly higher in females. In conclusion, this study provides age- and gender-adjusted normal reference ranges for IGF-I levels obtained with an automated immunometric chemiluminescent assay Immulite 2000 in healthy adult subjects.
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Affiliation(s)
- M Guitelman
- División Endocrinología, Hospital Carlos G Durand, Buenos Aires, Argentina
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Varewijck AJ, Lamberts SWJ, van der Lely AJ, Neggers SJCMM, Hofland LJ, Janssen JAMJL. Changes in circulating IGF1 receptor stimulating activity do not parallel changes in total IGF1 during GH treatment of GH-deficient adults. Eur J Endocrinol 2015; 173:119-27. [PMID: 25947141 DOI: 10.1530/eje-15-0048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/05/2015] [Indexed: 11/08/2022]
Abstract
CONTEXT Previously we demonstrated that IGF1 receptor stimulating activity (IGF1RSA) offers advantages in diagnostic evaluation of adult GH deficiency (GHD). It is unknown whether IGF1RSA can be used to monitor GH therapy. OBJECTIVE To investigate the value of circulating IGF1RSA for monitoring GH therapy. DESIGN/METHODS 106 patients (54 m; 52 f) diagnosed with GHD were included; 22 were GH-naïve, 84 were already on GH treatment and discontinued therapy 4 weeks before baseline values were established. IGF1RSA was determined by the IGF1R kinase receptor activating assay, total IGF1 by immunoassay (Immulite). GH doses were titrated to achieve total IGF1 levels within the normal range. RESULTS After 12 months, total IGF1 and IGF1RSA increased significantly (total IGF1 from 8.1 (95% CI 7.3-8.9) to 14.9 (95% CI 13.5-16.4) nmol/l and IGF1RSA from 115 (95% CI 104-127) to 181 (95% CI 162-202) pmol/l). After 12 months, total IGF1 normalized in 81% of patients, IGF1RSA in 51% and remained below normal in more than 40% of patients in whom total IGF1 had normalized. CONCLUSIONS During 12 months of GH treatment, changes in IGF1RSA did not parallel changes in total IGF1. Despite normalization of total IGF1, IGF1RSA remained subnormal in a considerable proportion of patients. At present our results have no short-term consequences for GH therapy of GHD patients. However, based on our findings we propose future studies to examine whether titrating GH dose against IGF1RSA results in a better clinical outcome than titrating against total IGF1.
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Affiliation(s)
- Aimee J Varewijck
- Division of EndocrinologyDepartment of Internal Medicine, Room D-443, Erasmus MC, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Steven W J Lamberts
- Division of EndocrinologyDepartment of Internal Medicine, Room D-443, Erasmus MC, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - A J van der Lely
- Division of EndocrinologyDepartment of Internal Medicine, Room D-443, Erasmus MC, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Sebastian J C M M Neggers
- Division of EndocrinologyDepartment of Internal Medicine, Room D-443, Erasmus MC, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Leo J Hofland
- Division of EndocrinologyDepartment of Internal Medicine, Room D-443, Erasmus MC, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Joseph A M J L Janssen
- Division of EndocrinologyDepartment of Internal Medicine, Room D-443, Erasmus MC, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
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Ketha H, Singh RJ. Clinical assays for quantitation of insulin-like-growth-factor-1 (IGF1). Methods 2015; 81:93-8. [PMID: 25937392 DOI: 10.1016/j.ymeth.2015.04.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 04/20/2015] [Accepted: 04/23/2015] [Indexed: 01/13/2023] Open
Abstract
Insulin-like growth factor 1 (IGF1), a 70 amino acid peptide hormone is the principal mediator of effects of growth hormone (GH). Since GH secretion is pulsatile in nature and is affected by many factors including sleep, feeding and exercise it is not a reliable marker for diagnosis of GH related disorders. On the other hand, IGF1 levels does not undergo short-term fluctuations in the manner that GH does making it the preferred IGF1 biomarker for the diagnosis of growth related disorders. There are several immunoassays available for IGF1 determination. Since majority (>90%) of IGF1 circulates as a ternary complex bound to its principal carrier/binding protein, IGF binding protein 3 (IGFBP3) and acid labile subunit (ALS), the assay methodology used to quantitate IGF1 has to dissociate IGF1 from IGFBPs prior to quantitation. IGFBPs are known to be a source of interference in immunoassays and many techniques have been employed to circumvent this issue. Immunoassays rely on antibody specificity towards IGF1 and differential cross reactivity towards IGFBPs. Mass spectrometry (MS) has also been employed for quantitation of IGF1. Liquid chromatography tandem mass spectrometry (LC-MS/MS) assays for IGF1 rely on generating tryptic peptides followed by selective reaction monitoring (SRM) while LC high resolution accurate-mass mass spectrometry (LC-HRAMS) approaches for intact IGF1 rely on mass accuracy for reliable, robust and accurate quantitation. This review article will focus on the clinical assays available and the clinical utility of quantitative assessment of IGF1. IGF1 quantitation using diverse assay platforms including immunoassay, LC-MS/MS and LC-HRAMS are discussed in detail.
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Affiliation(s)
- Hemamalini Ketha
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, United States
| | - Ravinder J Singh
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, United States.
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Zhang N, Liu H, Cui M, Du Y, Liu Z, Liu S. Direct determination of the binding sites of cisplatin on insulin-like growth factor-1 by top-down mass spectrometry. J Biol Inorg Chem 2015; 20:1-10. [PMID: 25344342 DOI: 10.1007/s00775-014-1202-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/26/2014] [Indexed: 01/12/2023]
Abstract
Cisplatin has been widely used in the chemotherapy of a variety of tumors, and the interactions of cisplatin with proteins play very important roles in its side effects and drug resistance, as well as its pharmacokinetics and the biodistribution. Insulin-like growth factor-1 (IGF-1) was found to be associated with the drug resistance of cisplatin. Here, the interaction between cisplatin and IGF-1 was investigated using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. IGF-1-Pt(NH3)Cl was the main mono-adduct and the trans labilization was important to the reaction between IGF-1 and cisplatin, while another special mono-adduct IGF-1-Pt(NH3)Cl2 was observed. The rapid and sensitive top-down mass spectrometry-based approach in linear ion trap mass spectrometer has been developed to identify the binding sites of cisplatin in IGF-1 directly without tedious enzyme digestion. Three binding sites (Met59, Arg56 and Cys6) of cisplatin in IGF-1 were determined. The results not only provide a rapid and efficient way to identify the platinum binding sites in proteins, but also indicate that the binding of cisplatin could promote the fragmentation of IGF-1 and the rupture of disulfide bond.
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Affiliation(s)
- Ningbo Zhang
- Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, People's Republic of China
- University of the Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Huan Liu
- Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, People's Republic of China
- University of the Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Meng Cui
- Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, People's Republic of China.
| | - Yonggang Du
- Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, People's Republic of China
- University of the Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Zhiqiang Liu
- Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, People's Republic of China
| | - Shuying Liu
- Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, People's Republic of China
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Cox HD, Lopes F, Woldemariam GA, Becker JO, Parkin MC, Thomas A, Butch AW, Cowan DA, Thevis M, Bowers LD, Hoofnagle AN. Interlaboratory Agreement of Insulin-like Growth Factor 1 Concentrations Measured by Mass Spectrometry. Clin Chem 2014; 60:541-8. [DOI: 10.1373/clinchem.2013.208538] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
BACKGROUND
Insulin-like growth factor 1 (IGF-1)7 is a key mediator of growth hormone (GH) action and a well-characterized biomarker of GH abuse. Current immunoassays for IGF-1 suffer from poor concordance between platforms, which makes comparison of results between laboratories difficult. Although previous work has demonstrated good interlaboratory imprecision of LC-MS/MS methods when plasma is supplemented with purified proteins, the interlaboratory imprecision of an endogenous protein in the nanogram-per-milliliter concentration range has not been reported.
METHODS
We deployed an LC-MS/MS method to quantify serum IGF-1 in 5 laboratories using 5 different instruments and analyzed 130 healthy human samples and 22 samples from patients with acromegaly. We determined measurement imprecision (CV) for differences due to instrumentation, calibration curve construction, method of calibration, and reference material.
RESULTS
Instrument-dependent variation, exclusive of digestion, across 5 different instrument platforms was determined to be 5.6%. Interlaboratory variation was strongly dependent on calibration. Calibration materials from a single laboratory resulted in less variation than materials made in individual laboratories (CV 5.2% vs 12.8%, respectively). The mean imprecision for 152 samples between the 5 laboratories was 16.0% when a calibration curve was made in each laboratory and 11.1% when a single-point calibration approach was used.
CONCLUSIONS
The interlaboratory imprecision of serum IGF-1 concentrations is acceptable for use of the assay in antidoping laboratories and in standardizing results across clinical laboratories. The primary source of variability is not derived from the sample preparation but from the method of calibration.
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Affiliation(s)
- Holly D Cox
- Sports Medicine Research and Testing Laboratory, Salt Lake City, UT
| | - Filipe Lopes
- Drug Control Centre, Analytical and Environmental Science Division, King's College London, London, UK
| | | | - Jessica O Becker
- Department of Laboratory Medicine, University of Washington, Seattle, WA
| | - Mark C Parkin
- Drug Control Centre, Analytical and Environmental Science Division, King's College London, London, UK
| | - Andreas Thomas
- Center for Preventive Doping Research, German Sport University Cologne, Cologne, Germany
| | | | - David A Cowan
- Drug Control Centre, Analytical and Environmental Science Division, King's College London, London, UK
| | - Mario Thevis
- Center for Preventive Doping Research, German Sport University Cologne, Cologne, Germany
| | | | - Andrew N Hoofnagle
- Department of Laboratory Medicine, University of Washington, Seattle, WA
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Vilar L, Valenzuela A, Ribeiro-Oliveira A, Gómez Giraldo CM, Pantoja D, Bronstein MD. Multiple facets in the control of acromegaly. Pituitary 2014; 17 Suppl 1:S11-7. [PMID: 24272033 PMCID: PMC3906559 DOI: 10.1007/s11102-013-0536-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
AIMS The current article provides a brief overview of the criteria for defining disease control in acromegaly. METHODS This was a retrospective, narrative review of previously published evidence chosen at the author's discretion along with an illustrative case study from Latin America. FINDINGS AND CONCLUSIONS In the strictest sense, "cure" in acromegaly is defined as complete restoration of normal pulsatile growth hormone secretion, although this is rarely achieved. Rather than "cure", as such, it is more appropriate to refer to disease control and remission, which is defined mainly in terms of specific biochemical targets (for growth hormone and insulin-like growth factor-1) that predict or correlate with symptoms, comorbidities and mortality. However, optimal management of acromegaly goes beyond biochemical control to include control of tumour growth (which may be independent of biochemical control) and comprehensive management of the symptoms and comorbidities typically associated with the disease, as these may not be adequately managed with acromegaly-specific therapy alone.
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Affiliation(s)
- Lucio Vilar
- Division of Endocrinology and Metabolism, Hospital das Clinicas, Federal University Medical School, Recife, Pernambuco Brazil
| | - Alex Valenzuela
- Department of Internal Medicine, Fundación Cardio-Infantil, Instituto de Cardiología, Universidad del Rosario, Bogotá, Colombia
| | - Antônio Ribeiro-Oliveira
- Department of Internal Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais Brazil
| | - Claudia M. Gómez Giraldo
- Hospital Universitario de San Ignacio and Organización Colsánitas Internacional, Bogotá, Colombia
| | | | - Marcello D. Bronstein
- Neuroendocrine Unit, Division of Endocrinology and Metabolism, Hospital das Clinicas, University of São Paulo Medical School, Av. Dr. Eneas de Carvalho, 255, 7ºandar, sala 7037, São Paulo, CEP 05403-000 Brazil
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Varewijck AJ, van der Lely AJ, Neggers SJCMM, Lamberts SWJ, Hofland LJ, Janssen JAMJL. In active acromegaly, IGF1 bioactivity is related to soluble Klotho levels and quality of life. Endocr Connect 2014; 3:85-92. [PMID: 24692508 PMCID: PMC4001616 DOI: 10.1530/ec-14-0028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The value of measuring IGF1 bioactivity in active acromegaly is unknown. Soluble Klotho (S-Klotho) level is elevated in active acromegaly and it has been suggested that S-Klotho can inhibit activation of the IGF1 receptor (IGF1R). A cross-sectional study was carried out in 15 patients with active acromegaly based on clinical presentation, unsuppressed GH during an oral glucose tolerance test, and elevated total IGF1 levels (>+2 s.d.). Total IGF1 was measured by immunoassay, IGF1 bioactivity by the IGF1R kinase receptor activation assay and S-Klotho by an ELISA. Quality of Life (QoL) was assessed by Acromegaly QoL (AcroQoL) Questionnaire and Short-Form-36 Health Survey Questionnaire (SF-36). Out of 15 patients, nine had IGF1 bioactivity values within the reference range. S-Klotho was higher in active acromegaly compared with controls. Age-adjusted S-Klotho was significantly related to IGF1 bioactivity (r=0.75, P=0.002) and to total IGF1 (r=0.62, P=0.02). IGF1 bioactivity and total IGF1 were inversely related to the physical component summary of the SF-36 (r=-0.78, P=0.002 vs r=-0.60, P=0.03). Moreover, IGF1 bioactivity, but not total IGF1, was significantly inversely related to the physical dimension of the AcroQoL Questionnaire (r=-0.60, P=0.02 vs r=-0.37, P=0.19). In contrast to total IGF1, IGF1 bioactivity was within the reference range in a considerable number of subjects with active acromegaly. Elevated S-Klotho levels may have reduced IGF1 bioactivity. Moreover, IGF1 bioactivity was more strongly related to physical measures of QoL than total IGF1, suggesting that IGF1 bioactivity may better reflect physical limitations perceived in active acromegaly.
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Targeted selected reaction monitoring mass spectrometric immunoassay for insulin-like growth factor 1. PLoS One 2013; 8:e81125. [PMID: 24278387 PMCID: PMC3836743 DOI: 10.1371/journal.pone.0081125] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 10/09/2013] [Indexed: 11/30/2022] Open
Abstract
Insulin-like growth factor 1 (IGF1) is an important biomarker of human growth disorders that is routinely analyzed in clinical laboratories. Mass spectrometry-based workflows offer a viable alternative to standard IGF1 immunoassays, which utilize various pre-analytical preparation strategies. In this work we developed an assay that incorporates a novel sample preparation method for dissociating IGF1 from its binding proteins. The workflow also includes an immunoaffinity step using antibody-derivatized pipette tips, followed by elution, trypsin digestion, and LC-MS/MS separation and detection of the signature peptides in a selected reaction monitoring (SRM) mode. The resulting quantitative mass spectrometric immunoassay (MSIA) exhibited good linearity in the range of 1 to 1,500 ng/mL IGF1, intra- and inter-assay precision with CVs of less than 10%, and lowest limits of detection of 1 ng/mL. The linearity and recovery characteristics of the assay were also established, and the new method compared to a commercially available immunoassay using a large cohort of human serum samples. The IGF1 SRM MSIA is well suited for use in clinical laboratories.
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Abstract
The free hormone hypothesis states that a hormone's physiological effects depend on the free hormone concentration, not the total hormone concentration. Although the in vivo relationship between free hormone and protein-bound hormone is complex, most experts have applied this view to the design of assays used to assess the free hormone concentration in the blood sampled for testing in vitro. The history of the measurement of free thyroxine, probably the most frequently requested free hormone determination, offers a good example of the approaches that have been taken. Methods that require physical separation of the free hormone from the protein-bound hormone must address both the potential disturbance in the equilibrium between the two, as well as the challenge of quantifying small levels of hormone accurately and precisely. The implementation of mass spectrometry in the clinical laboratory has helped to develop proposed reference measurement procedures. These must be utilized to standardize the variety of immunoassay approaches that currently represent options commercially available to the routine clinical laboratory. Practicing endocrinologists should discuss the details of the free hormone assays offered by the clinical laboratory they utilize for patient result reporting, and clinical laboratories should implement the recommendations of published guidelines to ensure that free hormone results using commercially available immunoassays are as accurate and precise as possible.
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Affiliation(s)
- James D Faix
- Stanford University School of Medicine, USA; Department of Pathology, Stanford University Medical Center, USA; Stanford Clinical Lab at Hillview, MC:5627, 3375 Hillview Avenue, Palo Alto, CA 94304-1204, USA.
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Guha N, Cowan DA, Sönksen PH, Holt RIG. Insulin-like growth factor-I (IGF-I) misuse in athletes and potential methods for detection. Anal Bioanal Chem 2013; 405:9669-83. [DOI: 10.1007/s00216-013-7229-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/02/2013] [Accepted: 07/08/2013] [Indexed: 11/30/2022]
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Abstract
INTRODUCTION Biochemical diagnosis of acromegaly relies on measurement of insulin-like growth factor-1 (IGF-1) and growth hormone (GH). An elevated IGF-1 level above the age- and gender-specific normal range and nonsuppression of GH to oral glucose load to a nadir < 0.4 ng/ml in sensitive assays are currently considered diagnostic of acromegaly. Lack of normative data for both IGF-1 and GH across a wide range of populations and ethnicities, interassay and intraassay laboratory variability, pulsatility of GH secretion, and effects of medications and hormones may confound interpretation of these biochemical tests. AREAS COVERED Clinical situations in which acromegaly should be suspected and/or investigated. Strengths and limitations of current IGF-1/GH assays are discussed. Clinical scenarios with discordant GH suppression test and IGF-1 levels and, briefly, acromegaly in pregnancy, prolactin-cosecreting tumors, familial acromegaly, and nonpituitary acromegaly are also discussed. EXPERT OPINION Serum IGF-1 is the cornerstone and in most cases the stand-alone test in the diagnosis and follow-up in patients with acromegaly. Diagnosis depends on the accurate and reliable measurement of serum IGF-1. GH suppression testing is currently used in limited clinical setting. Standardization of IGF-1 assay and development of normative data across a wide population base are needed. Newer bioassays for IGF-1 hold promise for future.
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Affiliation(s)
- Subramanian Kannan
- Endocrinology and Metabolism Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk F20, Cleveland, OH 44195, USA
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Tschuor F, Zini E, Schellenberg S, Wenger M, Boretti FS, Reusch CE. Evaluation of four methods used to measure plasma insulin-like growth factor 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases. Am J Vet Res 2013; 73:1925-31. [PMID: 23176419 DOI: 10.2460/ajvr.73.12.1925] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate 4 methods used to measure plasma insulin-like growth factor (IGF) 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases. ANIMALS 39 healthy cats, 7 cats with diabetes mellitus, and 33 cats with other diseases. PROCEDURES 4 assays preceded by different sample preparation methods were evaluated, including acid chromatography followed by radioimmunoassay (AC-RIA), acid-ethanol extraction followed by immunoradiometry assay (AEE-IRMA), acidification followed by immunochemiluminescence assay (A-ICMA), and IGF-2 excess followed by RIA (IE-RIA). Validation of the methods included determination of precision, accuracy, and recovery. The concentration of IGF-1 was measured with all methods, and results were compared among cat groups. RESULTS The intra-assay coefficient of variation was < 10% for AC-RIA, A-ICMA, and AEE-IRMA and 14% to 22% for IE-RIA. The linearity of dilution was close to 1 for each method. Recovery rates ranged from 69% to 119%. Five healthy cats had IGF-1 concentrations > 1,000 ng/mL with the AEE-IRMA, but < 1,000 ng/mL with the other methods. Compared with healthy cats, hyperthyroid cats had significantly higher concentrations of IGF-1 with the A-ICMA method, but lower concentrations with the IE-RIA method. Cats with lymphoma had lower IGF-1 concentrations than did healthy cats regardless of the method used. CONCLUSIONS AND CLINICAL RELEVANCE Differences in the methodologies of assays for IGF-1 may explain, at least in part, the conflicting results previously reported in diabetic cats. Disorders such as hyperthyroidism and lymphoma affected IGF-1 concentrations, making interpretation of results more difficult if these conditions are present in cats with diabetes mellitus.
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Affiliation(s)
- Flurin Tschuor
- Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland
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Neidert MC, Sze L, Zwimpfer C, Sarnthein J, Seifert B, Frei K, Leske H, Rushing EJ, Schmid C, Bernays RL. Soluble α-klotho: a novel serum biomarker for the activity of GH-producing pituitary adenomas. Eur J Endocrinol 2013; 168:575-83. [PMID: 23360820 DOI: 10.1530/eje-12-1045] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Klotho is a lifespan-influencing gene expressed mainly in the kidneys. Soluble α-Klotho (αKL) is released into the circulation. In this study, we present baseline αKL serum levels of patients with acromegaly compared with controls with other pituitary adenomas and assess changes following transsphenoidal surgery. DESIGN Prospective controlled study. METHODS We measured soluble αKL (sandwich ELISA) and IGF1 (RIA) in sera of 14 patients (eight females and six males) with active acromegaly and in 22 control patients (13 females and nine males) operated for non-GH-producing pituitary adenomas. Immunohistochemical staining for Klotho was performed in resected adenomas and in normal pituitary tissue samples. RESULTS Soluble αKL was high in the acromegaly group preoperatively (median 4217 pg/ml, interquartile range (IQR) 1812-6623 pg/ml) and declined after surgery during early follow-up (2-6 days; median 645 pg/ml, IQR 550-1303 pg/ml) (P<0.001) and during late follow-up (2-3 months post-operatively; median 902 pg/ml, IQR 497-1340 pg/ml; P<0.001). In controls, preoperative soluble αKL was significantly lower than in acromegalics, 532 pg/ml (400-677 pg/ml; P<0.001). Following surgery, soluble αKL remained low during early and late follow-up - changes over time within the control group were not statistically significant. These results were independent of age, sex and kidney function. Klotho staining was equal or slightly decreased in GH-positive adenomas compared with controls. CONCLUSION High soluble αKL serum levels were specific to GH-producing adenomas and decreased rapidly following adenoma removal. Thus, soluble αKL appears to be a new specific and sensitive biomarker reflecting disease activity in acromegaly. Similar Klotho staining patterns in controls and acromegalics suggest that the rise in serum αKL is caused by systemic actions of pituitary GH rather than due to increased expression of Klotho by the pituitary (adenoma).
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Affiliation(s)
- Marian Christoph Neidert
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
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Varewijck AJ, Lamberts SWJ, Neggers SJCMM, Hofland LJ, Janssen JAMJL. IGF-I bioactivity might reflect different aspects of quality of life than total IGF-I in GH-deficient patients during GH treatment. J Clin Endocrinol Metab 2013; 98:761-8. [PMID: 23295465 DOI: 10.1210/jc.2012-2901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
CONTEXT No relationship has been found between improvement in quality of life (QOL) and total IGF-I during GH therapy. AIM Our aim was to investigate the relationship between IGF-I bioactivity and QOL in GH-deficient (GHD) patients receiving GH for 12 months. METHODS Of 106 GHD patients, 84 on GH treatment discontinued therapy 4 weeks before establishing baseline values and 22 were GH-naive. IGF-I bioactivity was determined by IGF-I kinase receptor activation assay, total IGF-I by immunoassay (Immulite), and QOL by the disease-specific Question on Life Satisfaction Hypopituitarism (QLS-H) module and by the general SF-36 questionnaire (SF-36Q). RESULTS IGF-I bioactivity increased after 6 months (-2.5 vs -1.9 SD, P < .001) and did not further increase after 12 months (-1.8 SD, P = .23); total IGF-I increased from -2.3 to -0.9 SD (P < .001) and to -0.6 SD (P = .005), respectively. QLS-H did not change over 12 months (-0.66 ± 0.16 to -0.56 ± 0.17 SD [P = .42] to -0.68 ± 0.17 SD [P = .22]). The mental component summary of the SF-36Q increased from 47.4 (38.7-52.8) to 50.2 (43.1-55.3) (P = .001) and did not further improve (49.4 [42.1-54.1], P = .19); the physical component summary did not change (47.5 [42.0-54.2] vs 47.0 [41.9-55.3], P = .91, vs 48.3 [39.9-55.4], P = .66). After 12 months, IGF-I bioactivity was related to QLS-H (r = 0.28, P = .01); total IGF-I was not (r = 0.10, P = .37). IGF-I bioactivity and total IGF-I were related to PCS (r = 0.35, P = .001; and r = 0.31, P = .003). CONCLUSION IGF-I bioactivity remained subnormal after GH treatment and was positively related to QLS-H, whereas total IGF-I was not. This suggests that IGF-I bioactivity reflects different aspects of QOL than total IGF-I in GHD patients during GH treatment.
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Affiliation(s)
- Aimee J Varewijck
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, 3015 CE Rotterdam, The Netherlands
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Abstract
The growth hormone/insulin-like growth factor (GH/IGF) axis is widely investigated in disorders of growth, development, and anterior pituitary function. Methods are described for three hormones in this axis (growth hormone, IGF-I, and IGF binding protein-3). Enzyme-linked immunosorbent assays (ELISAs) are described as they combine the specificity of antibody-antigen interactions with the sensitivity of simple enzyme assays. Many commercial immunoassays are available for the measurement of GH and IGF-I, and the main problems encountered in the measurement of these clinically important hormones are discussed.
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Affiliation(s)
- Nishan Guha
- Department of Clinical Biochemistry, John Radcliffe Hospital, Oxford, UK
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43
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Boero L, Manavela M, Danilowicz K, Alfieri A, Ballarino MC, Chervin A, García-Basavilbaso N, Glerean M, Guitelman M, Loto MG, Nahmías JA, Rogozinski AS, Servidio M, Vitale NM, Katz D, Fainstein Day P, Stalldecker G, Mallea-Gil MS. Comparison of two immunoassays in the determination of IGF-I levels and its correlation with oral glucose tolerance test (OGTT) and with clinical symptoms in acromegalic patients. Pituitary 2012; 15:466-71. [PMID: 21960211 DOI: 10.1007/s11102-011-0351-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The aim of our study was to evaluate two different methodologies in IGF-I levels determination, its correlation with GH nadir in OGTT <1 and <0.4 ng/ml and with clinical symptoms in acromegalic patients. We analyzed 37 patients. Sixteen patients had not undergone any kind of treatment (Group 1). Twenty-one patients underwent surgery as primary treatment, and after that, some of them another kind of treatment (except pegvisomant) (Group 2). Serum IGF-I levels were measured by Immulite-1000 (IMM) and by an immunoradiometric assay (DSL) and, GH by immunochemiluminometric assay. IGF-I levels by IMM and by DSL showed a significant difference. When we analyzed in both groups the concordance by crosstabs-Kappa coefficients, between different parameters, GH nadir <1 and <0.4 ng/ml with IGF-I by DSL and IMM showed concordance in group 1, but in group 2 only GH nadir <1 and <0.4 ng/ml had a weak concordance with IGF-I by IMM. When we analyzed clinical symptoms in the patients and, GH nadir <1 and <0.4 ng/ml and IGF-I levels by both methodologies, more than 90% of clinically active patients had abnormal GH response or/and elevated IGF-I levels in group 1, but less than 70% in group 2. In the 8 patients under medical treatment, GH nadir was higher than 0.4 ng/ml in all patients, and IGF-I levels were elevated in 8/8 by DSL and in 6/8 by IMM. In conclusion, discrepant GH and IGF-I levels in the diagnosis and follow-up of patients with acromegaly requires consideration of many factors that influence these parameters.
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Affiliation(s)
- Laura Boero
- Departamento de Neuroendocrinología, Sociedad Argentina de Endocrinología y Metabolismo, Diaz Velez 3889, 1200 Buenos Aires, Argentina.
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Bystrom C, Sheng S, Zhang K, Caulfield M, Clarke NJ, Reitz R. Clinical utility of insulin-like growth factor 1 and 2; determination by high resolution mass spectrometry. PLoS One 2012; 7:e43457. [PMID: 22984427 PMCID: PMC3439428 DOI: 10.1371/journal.pone.0043457] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 07/25/2012] [Indexed: 11/18/2022] Open
Abstract
Measurement of insulin-like growth factor-1 (IGF-I) has utility for the diagnosis and management of growth disorders, but inter-assay comparison of results has been complicated by a multitude of reference standards, antibodies, detection methods, and pre-analytical preparation strategies. We developed a quantitative LC-MS method for intact IGF-I, which has advantages in throughput and complexity when compared to mass spectrometric approaches that rely on stable isotope dilution analysis of tryptic peptides. Since the method makes use of full-scan data, the assay was easily extended to provide quantitative measurement of IGF-II using the same assay protocol. The validated LC-MS assay for IGF-I and IGF-II provides accurate results across the pediatric and adult reference range and is suitable for clinical use.
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Affiliation(s)
- Cory Bystrom
- Cleveland Heart Lab, Cleveland, Ohio, United States of America
| | - Shijun Sheng
- Thermo Scientific, San Jose, California, United States of America
| | - Ke Zhang
- Quest Diagnostics – Nichols Institute, San Juan Capistrano, California, United States of America
| | - Michael Caulfield
- Quest Diagnostics – Nichols Institute, San Juan Capistrano, California, United States of America
| | - Nigel J. Clarke
- Quest Diagnostics – Nichols Institute, San Juan Capistrano, California, United States of America
| | - Richard Reitz
- Quest Diagnostics – Nichols Institute, San Juan Capistrano, California, United States of America
- * E-mail:
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Frystyk J. Quantification of the GH/IGF-axis components: lessons from human studies. Domest Anim Endocrinol 2012; 43:186-97. [PMID: 22153974 DOI: 10.1016/j.domaniend.2011.11.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/08/2011] [Accepted: 11/09/2011] [Indexed: 11/30/2022]
Abstract
Originally, the circulating bioactivity of IGF-I was estimated by bioassays measuring the ability of serum to stimulate uptake of labeled sulfate or thymidine in cultures of costal cartilage or by the ability of serum to stimulate the uptake of glucose in fat tissue cultures. However, because of their laborious and unspecific nature, the original bioassays were quickly abandoned with the development of the first RIA for IGF-I in 1977. Consequently, for the past three decades the endogenous IGF-I bioactivity has been almost exclusively estimated by the use of immunoassays. Beyond any doubt, the immunoassays have provided an extensive insight into IGF-I physiology and pathophysiology. However, immunoassays ignore the presence of the IGFBPs, which are important regulators of IGF-I action in vivo. In addition, immunoassays do not consider the presence of IGF-II, which also interacts with the IGF-I receptor (IGF-IR). This aroused our interest to reintroduce the bioassay; therefore, we established a cell-based kinase receptor activation (KIRA) assay based on cells transfected with the human IGF-IR. The output signal of the KIRA assay is IGF-IR phosphorylation, and, as such, it is highly specific. Further, because detection of phosphorylated IGF-IRs is based on modern immunoassay techniques, the overall performance of the assay is close to that of a traditional IGF-I immunoassay. The first part of this review comprises a short description of the bioassay, and a more in-depth presentation of the data that have been obtained so far. It will be demonstrated that the bioassay is indeed able to yield novel information on the IGF system, most likely because it is able to integrate the different components of the IGF system into one signal: IGF-IR activation. As IGF-I, circulating GH is bound to larger proteins, the far most important GH-binding protein (GHBP) is identical to the extracellular domain of the GH receptor (GHR). Because of its origin, GHBP binds GH with the same affinity as GHR and, consequently, GHBP may affect GH bioactivity as well as pharmacokinetics. To improve our knowledge on the complex interaction between GH and GHBP in vivo, we found it of interest to develop a method for determination of free GH. To this end, we developed an ultrafiltration assay that enabled isolation of free GH in undiluted serum during approached in vivo-like conditions. The last part of this review presents our current data on free GH and its interaction with GHBP.
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Affiliation(s)
- J Frystyk
- Medical Research Laboratories, Institute of Clinical Medicine, Faculty of Health Sciences, Aarhus University and Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, DK-8000 Aarhus C, Denmark.
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Gatti R, De Palo EF, Antonelli G, Spinella P. IGF-I/IGFBP system: metabolism outline and physical exercise. J Endocrinol Invest 2012; 35:699-707. [PMID: 22714057 DOI: 10.3275/8456] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The GH/IGF-I system plays a well-known hormonal role and its effects, mainly anabolic and insulin-sensitizing, are mediated through endocrine as well as paracrine/ autocrine mechanisms. This system includes the binding proteins, namely GH binding proteins and IGF-I binding proteins (IGFBP). As expected, this axis plays a key role in organism modification in consequence of a physical exercise. Physical activity, training, and exercise capacity chiefly involve anabolism process modifications of various tissues, in particular muscular adjustments. Numerous investigators found a correlation among the level of exercise tolerance, muscle strength or walking speed and IGF-I/IGFBP-3 concentrations. However, also inverse and absent correlations between circulating IGF-I concentrations and acute or chronic exercise responses have been reported. IGF-I is generally accepted as an important GH mediator with metabolic effects, through both endocrine and paracrine or autocrine mechanisms. GH is the main regulator of the hepatic synthesis of IGF-I and IGFBP-3, which is the most abundant IGF carrier in human plasma. Recently, it has been shown that the physical exercise stimulatory impact on skeletal muscles is mediated through an increased local IGF-I synthesis with an IGFPB involvement. An absent association of exercise performance and circulating IGF-I may indicate that exercise will exert muscle strength by predominately locally derived paracrine or autocrine mediators rather than endocrine circulating IGF-I. The present review considers the general aspects of the IGF/IGFPB system and the role of the IGF/IGFPB system in relation to physical exercise (type, duration, etc.) taking into account the training aspects.
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Affiliation(s)
- R Gatti
- Clinical Biochemistry, Department of Medical Diagnostic Sciences and Special Therapies, University of Padua, Padua, Italy
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Coutant R, Dörr HG, Gleeson H, Argente J. Diagnosis of endocrine disease: limitations of the IGF1 generation test in children with short stature. Eur J Endocrinol 2012; 166:351-7. [PMID: 22048966 DOI: 10.1530/eje-11-0618] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The IGF1 generation test (IGFGT) is often used during the assessment of suspected GH insensitivity (GHI). We report the results of a survey undertaken in 2010 to determine the use of IGFGT amongst members of the European Society for Paediatric Endocrinology to evaluate suspected GHI. The literature surrounding the usefulness and limitations of IGFGT are reviewed, and recommendations provided for its use. Of 112 paediatric endocrinologists from 30 countries who responded to the survey, 91 (81%) reported that they had used the IGFGT in the previous 2 years; >10 IGFGT protocols were used. The IGFGT impacted treatment decisions for 97% of the respondents and was a prerequisite for recombinant human IGF1 treatment for 45% of respondents. From a literature review, sensitivity of the IGFGT was evaluated as 77-91% in molecularly proven cases of GHI; specificity was ≤97%, depending on the protocol. The positive predictive value of the IGFGT is likely to be low, as the frequency of normality is predictably higher than that of abnormality in GH signalling. Given the limitations of the IGFGT in the most severe cases of GHI syndrome (GHIS), the ability of the IGFGT to detect less severe GHIS is doubtful. In a pragmatic approach, the IGFGT may not be useful for the diagnosis of GHIS.
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Affiliation(s)
- Régis Coutant
- Endocrinologie Diabétologie Pédiatrique, Pôle Enfant, CHU Angers, 4 rue Larrey, 49933 Angers, Cedex 9, France
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Bystrom CE, Sheng S, Clarke NJ. Narrow Mass Extraction of Time-of-Flight Data for Quantitative Analysis of Proteins: Determination of Insulin-Like Growth Factor-1. Anal Chem 2011; 83:9005-10. [DOI: 10.1021/ac201800g] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Cory E. Bystrom
- Quest Diagnostics, Nichols Institute, San Juan Capistrano, California 92694, United States
| | - Shijun Sheng
- Quest Diagnostics, Nichols Institute, San Juan Capistrano, California 92694, United States
| | - Nigel J. Clarke
- Quest Diagnostics, Nichols Institute, San Juan Capistrano, California 92694, United States
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49
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Tinworth KD, Wynn PC, Boston RC, Harris PA, Sillence MN, Thevis M, Thomas A, Noble GK. Evaluation of commercially available assays for the measurement of equine insulin. Domest Anim Endocrinol 2011; 41:81-90. [PMID: 21741576 DOI: 10.1016/j.domaniend.2011.05.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 04/08/2011] [Accepted: 05/02/2011] [Indexed: 11/20/2022]
Abstract
Determining circulating equine insulin concentrations is becoming increasingly important in equine clinical practice and research. Most available assays are optimized for human medicine, but there is strong equine cross-reactivity because of the highly conserved nature of insulin. To identify an accurate and reliable assay for equine insulin, 6 commercial immunoassays were evaluated for precision, accuracy, and specificity. Only 1 assay initially reached the requisite standard: Mercodia Equine Insulin Enzyme-linked Immunosorbent assay (ELISA). Plasma matrix interferences were identified when the provided assay buffer was used with the Siemens Count-a-Coat Insulin radioimmunoassay (RIA) but not when charcoal-stripped equine plasma was used as the diluent. This modified RIA and the Mercodia Equine Insulin ELISA were evaluated further by directly examining accuracy by comparing their results for 18 equine plasma samples with values obtained using liquid chromatography and high-resolution/high-accuracy mass spectrometry (LC-MS). Compared with LC-MS measurements, the modified Siemens Insulin RIA rendered a moderate Lin's concordance coefficient (ρ(c)) of 0.41, whereas the Mercodia Equine Insulin ELISA rendered a very poor ρ(c) of 0.06. This suggests that the Siemens Insulin RIA is appropriate to use for routine evaluations when LC-MS is not available.
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Affiliation(s)
- K D Tinworth
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia
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50
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Clemmons DR. Consensus Statement on the Standardization and Evaluation of Growth Hormone and Insulin-like Growth Factor Assays. Clin Chem 2011; 57:555-9. [DOI: 10.1373/clinchem.2010.150631] [Citation(s) in RCA: 252] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Growth hormone (GH) and insulin-like growth factor I (IGF-I) measurements are widely used in the diagnosis of disorders of GH secretion, evaluation of children with short stature from multiple causes, management of disorders that lead to nutritional insufficiency or catabolism, and monitoring both GH and IGF-I replacement therapy. Therefore, there is an ongoing need for accurate and precise measurements of these 2 peptide hormones. Representatives of the Growth Hormone Research Society, the IGF Society, and the IFCC convened an international workshop to review assay standardization, requirements for improving assay comparability, variables that affect assay interpretation, technical factors affecting assay performance, assay validation criteria, and the development and use of normative data. Special attention was given to preanalytical conditions, the use of international commutable reference standards, antibody specificity, matrix requirements, QC analysis, and interference by binding proteins. Recommendations for each of these variables were made for measurements of each peptide. Additionally, specific criteria for IGF-I were recommended for age ranges of normative data, consideration of Tanner staging, and consideration of the effect of body mass index. The consensus statement concludes that major improvements are necessary in the areas of assay performance and comparability. This group recommends that a commutable standard for each assay be implemented for worldwide use and that its recommendations be applied to accomplish the task of providing reliable and clinically useful results.
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Affiliation(s)
- David R Clemmons
- Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC
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