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Multiplexed quantification of insulin and C-peptide by LC-MS/MS without the use of antibodies. J Mass Spectrom Adv Clin Lab 2022; 25:19-26. [PMID: 35734440 PMCID: PMC9207678 DOI: 10.1016/j.jmsacl.2022.06.003] [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: 04/11/2022] [Revised: 06/08/2022] [Accepted: 06/08/2022] [Indexed: 11/30/2022] Open
Abstract
Simultaneous quantification of insulin and C-peptide without antibodies. Proteolysis with Glu-C permits sensitive and precise measurements. Calibration with certified reference material provides traceability. Relatively large bias when compared with a commercially available immunoassay.
Introduction The measurement of insulin and C-peptide provides a valuable tool for the clinical evaluation of hypoglycemia. In research, these biomarkers are used together to better understand hyperinsulinemia, hepatic insulin clearance, and beta cell function. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an attractive approach for the analysis of insulin and C-peptide because the platform is specific, can avoid certain limitations of immunoassays, and can be multiplexed. Previously described LC-MS/MS methods for the simultaneous quantification of insulin and C-peptide measure the intact analytes and most have relied on immunoaffinity enrichment. These approaches can be limited in terms of sensitivity and interference from auto-antibodies, respectively. We have developed a novel method that does not require antibodies and uses proteolytic digestion to yield readily ionizable proteotypic peptides that enables the sensitive, specific, and simultaneous quantitation of insulin and C-peptide. Methods Serum samples were precipitated with acetonitrile. Analytes were enriched using solid phase extraction and then digested with endoproteinase Glu-C. Surrogate peptides for insulin and C-peptide were analyzed using targeted LC-MS/MS. Results Inter-day imprecision was below 20 %CV and linearity was observed down to the lower limit of quantitation for both analytes (insulin = 0.09 ng/mL, C-peptide = 0.06 ng/mL). Comparison to a commercially available insulin immunoassay (Beckman Coulter UniCel DxI 600 Access) revealed a 30% bias between methods. Conclusion A novel LC-MS/MS method for the simultaneous analysis of insulin and C-peptide using Glu-C digestion was developed and evaluated. A detailed standard operating procedure is provided to help facilitate implementation in other laboratories.
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Déchelotte B, Girot H, Chagraoui A, Prevost G, Brunel V. Dipotassium ethylenediaminetetraacetic acid is better than tripotassium salt for electrochemiluminescence insulin measurement. Clin Chim Acta 2016; 463:45-46. [DOI: 10.1016/j.cca.2016.09.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 09/19/2016] [Indexed: 10/20/2022]
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Wu ZQ, Lu J, Chen H, Chen W, Xu HG. Individualized correction of insulin measurement in hemolyzed serum samples. Immunol Res 2016; 65:605-608. [PMID: 27817149 DOI: 10.1007/s12026-016-8878-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Insulin measurement plays a key role in the investigation of patients with hypoglycemia, subtype classification of diabetes mellitus, insulin resistance, and impaired beta cell function. However, even slight hemolysis can negatively affect insulin measurement due to RBC insulin-degrading enzyme (IDE). Here, we derived and validated an individualized correction equation in an attempt to eliminate the effects of hemolysis on insulin measurement. The effects of hemolysis on insulin measurement were studied by adding lysed self-RBCs to serum. A correction equation was derived, accounting for both percentage and exposure time of hemolysis. The performance of this individualized correction was evaluated in intentionally hemolyzed samples. Insulin concentration decreased with increasing percentage and exposure time of hemolysis. Based on the effects of hemolysis on insulin measurement of 17 donors (baseline insulin concentrations ranged from 156 to 2119 pmol/L), the individualized hemolysis correction equation was derived: INScorr = INSmeas/(0.705lgHbplasma/Hbserum - 0.001Time - 0.612). This equation can revert insulin concentrations of the intentionally hemolyzed samples to values that were statistically not different from the corresponding insulin baseline concentrations (p = 0.1564). Hemolysis could lead to a negative interference on insulin measurement; by individualized hemolysis correction equation for insulin measurement, we can correct and report reliable serum insulin results for a wide range of degrees of sample hemolysis. This correction would increase diagnostic accuracy, reduce inappropriate therapeutic decisions, and improve patient satisfaction with care.
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Affiliation(s)
- Zhi-Qi Wu
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guang Zhou Road, Nanjing, Jiangsu Province, 210029, China
| | - Ju Lu
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guang Zhou Road, Nanjing, Jiangsu Province, 210029, China
| | - Huanhuan Chen
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guang Zhou Road, Nanjing, Jiangsu Province, 210029, China
| | - Wensen Chen
- Department of Infection Control and Hospital Epidemiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Hua-Guo Xu
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guang Zhou Road, Nanjing, Jiangsu Province, 210029, China.
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Labay LM, Bitting CP, Legg KM, Logan BK. The Determination of Insulin Overdose in Postmortem Investigations. Acad Forensic Pathol 2016; 6:174-183. [PMID: 31239889 DOI: 10.23907/2016.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/19/2016] [Accepted: 05/24/2016] [Indexed: 01/17/2023]
Abstract
The analysis of biological specimens for the presence of exogenous insulin is of special interest in select postmortem investigations. Insulin analogues are primarily used to mediate the regulation of blood glucose concentrations; however, their use has also been implicated or suspected as a cause of death in suicides, accidents, and homicides. Toxicological analysis for these compounds is challenging due to the large molecular weight, the limited stability of insulin in whole blood, and complexities associated with sample preparation and instrumental testing. As a consequence, determination of insulin in postmortem specimens is not routinely offered by most forensic toxicology laboratories. Forensic death investigation is further complicated by interpretative difficulties such as the frequent absence of anatomical findings, concentration interpretation in known insulin users, and addressing the impact of chemical instability and postmortem redistribution. There are ongoing efforts, however, to develop and validate robust methods that may be used for this analysis on these challenging samples and that are capable of withstanding scientific and legal scrutiny for forensic use. In this regard, in recent years, methods for the detection of exogenous insulin in postmortem samples have been reported and results of this testing has been published in a handful of cases. The purpose of this article is to review the primary functions of insulin, the disease states associated with the therapeutic use of exogenous insulin, the current state of laboratory testing, and to provide case summaries that summarize the timeline of advancements and underscore the importance of this work.
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Affiliation(s)
| | | | - Kevin M Legg
- Center for Forensic Science Research and Education
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Wu ZQ, Lu J, Xu HG. Hemolysis Affects C-Peptide Immunoassay. J Clin Lab Anal 2016; 30:1232-1235. [PMID: 27231209 DOI: 10.1002/jcla.22008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/04/2016] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND C-peptide is used widely as a marker of insulin secretion, and it participates in the inflammatory response and contributes to the development of coronary artery disease (CAD) in patients with type 2 diabetes mellitus (T2DM). Previous studies have reported that C-peptide measurement was unaffected by hemolysis. However, we found that hemolysis negatively affected C-peptide assay in routine laboratory practice. We further established and validated an individualized hemolysis correction equation to correct and report accurate serum C-peptide results for hemolyzed samples. METHODS We studied the effects of hemolysis on C-peptide assay by adding lysed self red blood cells (self-RBCs) to serum. An individualized correction equation was derived. Further, we evaluated the performance of this individualized correction equation by artificially hemolyzed samples. RESULTS C-peptide concentration decreased with increasing degree and exposure time of hemolysis. The individualized hemolysis correction equation derived: C-Pcorr = C-Pmeas /(0.969-1.5Hbserum/plasma -5.394 ×10-5 Time), which can correct bias in C-peptide measurement caused by hemolysis. CONCLUSIONS Hemolysis negatively affects C-peptide measurement. We can correct and report accurate serum C-peptide results for a wide range of degrees of sample hemolysis by individualized hemolysis correction equation for C-peptide assay. This correction would improve diagnostic accuracy and reduce inappropriate therapeutic decisions.
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Affiliation(s)
- Zhi-Qi Wu
- Department of Laboratory Medicine, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Ju Lu
- Department of Laboratory Medicine, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Hua-Guo Xu
- Department of Laboratory Medicine, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China.
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Zornitzki T, Blaychfeld-Magnazi M, Knobler H, Ulman M. THE EFFECT OF PHLEBOTOMY-INDUCED HEMOLYSIS ON INSULIN LEVEL DETERMINATION. Endocr Pract 2015; 21:1093-7. [PMID: 26121452 DOI: 10.4158/ep15698.or] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To examine the effect of phlebotomy-induced hemolysis on serum insulin and C-peptide measurement by an immunochemiluminometric assay. METHODS As part of a study designed to evaluate β-cell function in a group of adults with newly diagnosed type 2 diabetes, we tested insulin and C-peptide levels in 1,048 samples. In order to evaluate the effect of phlebotomy-induced hemolysis, we determined insulin and C-peptide levels simultaneously in hemolyzed and nonhemolyzed samples. RESULTS Forty-seven (4.5%) of the 1,048 samples were affected by hemolysis. In 26 cases, we had paired hemolyzed and nonhemolyzed serum samples that allowed a simultaneous comparison. We found that all degrees of hemolysis led to a significant decrease in insulin level. In hemolyzed serum, the median (interquartile range) of the insulin was 5.6 (1.8 to 24.3) mIU/L, versus 21.3 (11.4 to 48.5) mIU/L in nonhemolyzed serum, representing a 25 to 98% loss. This phenomenon was not found for C-peptide levels. CONCLUSION Clinicians have to be aware that even a mild degree of phlebotomy-induced hemolysis has a significant effect on serum insulin level determination, which can lead to misinterpretation of test results. This finding has important implications, especially in the evaluation of suspected cases of hyperinsulinemic hypoglycemia.
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Differential interferences of hemoglobin and hemolysis on insulin assay with the Abbott Architect®-Ci8200 immunoassay. Clin Biochem 2014; 47:445-7. [DOI: 10.1016/j.clinbiochem.2014.01.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 12/18/2013] [Accepted: 01/24/2014] [Indexed: 11/29/2022]
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Bowen RAR, Remaley AT. Interferences from blood collection tube components on clinical chemistry assays. Biochem Med (Zagreb) 2014; 24:31-44. [PMID: 24627713 PMCID: PMC3936985 DOI: 10.11613/bm.2014.006] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 01/03/2014] [Indexed: 12/21/2022] Open
Abstract
Improper design or use of blood collection devices can adversely affect the accuracy of laboratory test results. Vascular access devices, such as catheters and needles, exert shear forces during blood flow, which creates a predisposition to cell lysis. Components from blood collection tubes, such as stoppers, lubricants, surfactants, and separator gels, can leach into specimens and/or adsorb analytes from a specimen; special tube additives may also alter analyte stability. Because of these interactions with blood specimens, blood collection devices are a potential source of pre-analytical error in laboratory testing. Accurate laboratory testing requires an understanding of the complex interactions between collection devices and blood specimens. Manufacturers, vendors, and clinical laboratorians must consider the pre-analytical challenges in laboratory testing. Although other authors have described the effects of endogenous substances on clinical assay results, the effects/impact of blood collection tube additives and components have not been well systematically described or explained. This review aims to identify and describe blood collection tube additives and their components and the strategies used to minimize their effects on clinical chemistry assays.
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Affiliation(s)
- Raffick A R Bowen
- Department of Pathology, Stanford University, Stanford, CA 94305, USA
| | - Alan T Remaley
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, MD 20892, USA
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Simultaneous determination and validated quantification of human insulin and its synthetic analogues in human blood serum by immunoaffinity purification and liquid chromatography-mass spectrometry. Anal Bioanal Chem 2012; 404:1813-22. [DOI: 10.1007/s00216-012-6271-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 06/26/2012] [Accepted: 07/13/2012] [Indexed: 01/08/2023]
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El-sisi AE, Hegazy SK, Metwally SS, Wafa AM, Dawood NA. Effect of genetic polymorphisms on the development of secondary failure to sulfonylurea in egyptian patients with type 2 diabetes. Ther Adv Endocrinol Metab 2011; 2:155-64. [PMID: 23148181 PMCID: PMC3474636 DOI: 10.1177/2042018811415985] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVE This study investigated the possibility that genetic factors, such as polymorphism of K inward rectifier subunit (Kir6.2), E23K, and Arg(972) polymorphism of insulin receptor sub-strate-1 (IRS-1), may predispose patients to sulfonylurea failure. METHODS A total of 100 unrelated Egyptian patients with type 2 diabetes were recruited. They were divided into two equal groups: group I consisted of patients with secondary failure to sulfonylurea (hemoglobin A(1c) ≥ 8% despite sulfonylurea therapy) while group II consisted of patients whose condition was controlled with oral therapy. RESULTS Of all the patients, 45% and 14% were carriers of the K allele and Arg(972) variants respectively. The frequency of the K allele was 34% among patients with diabetes that was controlled with oral therapy and 56% among patients with secondary failure to sulfonylurea. The frequency of the Arg(972) IRS-1 variant was 6% among patients with diabetes controlled with oral therapy and 22% among patients with secondary failure. CONCLUSION The E23K variant of the Kir6.2 gene and Arg(972) IRS-1 variants are associated with increased risk for secondary failure to sulfonylurea.
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Affiliation(s)
| | | | | | | | - Naglaa A. Dawood
- Specialized Internal Medicine Hospital, Mansoura University, Lecturer in clinical pharmacy dept., Pharmacy collage, King Khalid University, KSA
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Stability of plasma adrenocorticotrophic hormone (ACTH): Influence of hemolysis, rapid chilling, time, and the addition of a maleimide. Clin Biochem 2010; 43:1478-80. [DOI: 10.1016/j.clinbiochem.2010.09.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/17/2010] [Accepted: 09/17/2010] [Indexed: 11/20/2022]
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Musshoff F, Hess C, Madea B. Disorders of glucose metabolism: post mortem analyses in forensic cases–part II. Int J Legal Med 2010; 125:171-80. [DOI: 10.1007/s00414-010-0510-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 08/24/2010] [Indexed: 11/24/2022]
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Comparison of a Luminescent Oxygen Channeling Immunoassay and an ELISA for detecting Insulin Aspart in human serum. J Pharm Biomed Anal 2010; 51:217-24. [DOI: 10.1016/j.jpba.2009.08.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 08/06/2009] [Accepted: 08/06/2009] [Indexed: 11/20/2022]
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Bowen RAR, Hortin GL, Csako G, Otañez OH, Remaley AT. Impact of blood collection devices on clinical chemistry assays. Clin Biochem 2009; 43:4-25. [PMID: 19822139 DOI: 10.1016/j.clinbiochem.2009.10.001] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 09/30/2009] [Accepted: 10/02/2009] [Indexed: 11/29/2022]
Abstract
Blood collection devices interact with blood to alter blood composition, serum, or plasma fractions and in some cases adversely affect laboratory tests. Vascular access devices may release coating substances and exert shear forces that lyse cells. Blood-dissolving tube additives can affect blood constituent stability and analytical systems. Blood tube stoppers, stopper lubricants, tube walls, surfactants, clot activators, and separator gels may add materials, adsorb blood components, or interact with protein and cellular components. Thus, collection devices can be a major source of preanalytical error in laboratory testing. Device manufacturers, laboratory test vendors, and clinical laboratory personnel must understand these interactions as potential sources of error during preanalytical laboratory testing. Although the effects of endogenous blood substances have received attention, the effects of exogenous substances on assay results have not been well described. This review will identify sources of exogenous substances in blood specimens and propose methods to minimize their impact on clinical chemistry assays.
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Affiliation(s)
- Raffick A R Bowen
- Department of Pathology, Stanford University, 300 Pasteur Drive, Room H1507 B, Stanford, CA 94305, USA.
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Sapin R. Interférences dans les immunodosages : mécanismes et conséquences en endocrinologie. ANNALES D'ENDOCRINOLOGIE 2008; 69:415-25. [DOI: 10.1016/j.ando.2008.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 04/08/2008] [Accepted: 04/21/2008] [Indexed: 10/22/2022]
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Hadi M, Bacharach SL, Whatley M, Libutti SK, Straus SE, Rao VK, Wesley R, Carrasquillo JA. Glucose and insulin variations in patients during the time course of a FDG-PET study and implications for the “glucose-corrected” SUV. Nucl Med Biol 2008; 35:441-5. [DOI: 10.1016/j.nucmedbio.2008.02.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 01/29/2008] [Accepted: 02/11/2008] [Indexed: 10/22/2022]
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Fung TT, Manson JE, Solomon CG, Liu S, Willett WC, Hu FB. The association between magnesium intake and fasting insulin concentration in healthy middle-aged women. J Am Coll Nutr 2006; 22:533-8. [PMID: 14684759 DOI: 10.1080/07315724.2003.10719332] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE We assessed the association between magnesium intake and fasting insulin levels in a large cohort of women. METHODS Female nurses free of diabetes, cardiovascular diseases and cancer from the Nurses Health Study provided blood samples between 1989-1990. We selected a sub-sample of 219 women for this analysis. Magnesium intake was assessed by a food frequency questionnaire in 1990 and categorized into quartiles. Cross-sectional geometric means of fasting insulin concentrations by quartiles of magnesium intake were obtained with Generalized Linear Model and adjusted for several risk factors and lifestyle characteristics. RESULTS After adjustment for age, body mass index (BMI), total energy, physical activity, hours per week spent sitting outside work, alcohol intake, smoking, and family history of diabetes, magnesium intake was inversely associated with fasting insulin concentration. The multivariate adjusted geometric mean for women in the lowest quartile of magnesium intake was 11.0 microU/mL and 9.3 microU/mL among those in the highest quartile of magnesium intake (p for trend = 0.04). The inverse association remained when we considered magnesium from only food sources. CONCLUSION Higher magnesium intake is associated with lower fasting insulin concentrations among women without diabetes. Because lower fasting insulin concentrations generally reflect greater insulin sensitivity, these findings provide a mechanism through which higher dietary magnesium intake may reduce the risk of developing type 2 diabetes mellitus.
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Affiliation(s)
- Teresa T Fung
- Department of Nutrition, Simmons College, 300 The Fenway, Boston, MA 02215, USA.
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Preissner CM, Reilly WM, Cyr RC, O'Kane DJ, Singh RJ, Grebe SKG. Plastic versus glass tubes: effects on analytical performance of selected serum and plasma hormone assays. Clin Chem 2004; 50:1245-7. [PMID: 15229156 DOI: 10.1373/clinchem.2004.034108] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Carol M Preissner
- Endocrine Laboratory, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
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Soudan B, Girardot C, Fermon C, Verlet E, Pattou F, Vantyghem MC. Extreme subcutaneous insulin resistance: a misunderstood syndrome. DIABETES & METABOLISM 2003; 29:539-46. [PMID: 14631332 DOI: 10.1016/s1262-3636(07)70069-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Extreme subcutaneous insulin resistance (SIR) is a rare syndrome characterized by severe resistance to subcutaneous insulin with normal intravenous insulin sensitivity. Its pathophysiology is unknown, though an increased insulin degrading activity has been suggested. We report the case of a 35 year-old female patient with type I diabetes since the age of 3. Despite five shots of insulin/day, the patient progressively developed permanent ketosis related to severe acquired SIR with insulin doses as high as 500 U/day. Subcutaneous infusion of insulin and lispro insulin through an external pump did not improve resistance: HbA(1c) levels remained between 14 and 18% (N<6.5%). After numerous ketoacidotic episodes, continuous ambulatory intravenous insulin infusion was attempted through a central port due to a lack of peripheral venous access. HbAlc improved (8.5%) and daily insulin needs decreased to below 40U. However, the treatment had to be discontinued because of thrombosis and infection at different times. Intraperitoneal insulin infusion with an external pump was then proposed. HbAlc improved to 8% during 18 months but several episodes of catheter infection and encapsulation led to its removal. An intraperitoneal pump was surgically implanted, leading to the stabilization of HbA(1c) to around 8%. An insulin degradation assay did not demonstrate any excess of insulin degrading activity in the patient's or controls' subcutaneous tissue; nevertheless, excessive amounts of insulin were found in the patient's derm compared to controls. This case report of acquired SIR raises the question of its treatment and mechanisms. Regarding treatment, intraperitoneal delivery of insulin appears to be the best solution, but the mechanisms underlying SIR still remain unclear.
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Affiliation(s)
- B Soudan
- Laboratory of Endocrinology, Lille University Hospital, Lille, France
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Abstract
We investigated the interference of insulin antibodies in two insulin immunometric assays (Bio-Rad and Elecsys) by measuring direct and free insulin in plasma from 30 patients without insulin antibodies (group 1), as screened by a sensitive radio-binding assay, and in plasma from 80 patients with insulin antibodies (group 2). In group 1, the direct/free insulin ratio did not differ from 1, showing the equivalence of free and direct insulin results in theses samples. In group 2, this ratio was markedly increased (mean: Bio-Rad 2.63, Elecsys 5.02) and correlated positively with the insulin antibody radio-binding assay result (r=0.92 for the correlation between Bio-Rad and Elecsys assays after log-transformation of the ratios). In samples containing insulin antibodies, direct insulin concentration was frequently lower than total (bound and unbound) insulin measured with the Bio-Rad and Elecsys assays. This study underlines the interference of insulin antibodies in insulin immunometric assays and the importance of assessing an insulin immunometric assay for sensitivity towards the presence of these antibodies.
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Affiliation(s)
- Rémy Sapin
- Unité d'Analyses Endocriniennes, CNRS UMR 7004, Université Louis Pasteur, Faculté de Médecine, Strasbourg, France.
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Vieira JGH. Avaliação dos Potenciais Problemas Pré-Analíticos e Metodológicos em Dosagens Hormonais. ACTA ACUST UNITED AC 2002. [DOI: 10.1590/s0004-27302002000100003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dosagens hormonais são particularmente susceptíveis a potenciais interferências, que podem ser de várias origens. Estes fatores interferentes podem ser divididos em pré-analíticos, metodológicos e pós-analíticos. Nesta revisão nós procuramos abordar os dois primeiros tipos de interferentes. Os pré-analíticos incluem variações fisiológicas relativas a dieta, ritmos biológicos, estresse, doenças não endócrinas, uso de medicações hormonais, etc. Podem também englobar problemas de coleta de amostras, que incluem o tipo de material utilizado, as condições de manuseio e envio das amostras, e as conseqüências na preservação física dos analitos. Já os interferentes metodológicos podem ser de várias origens e incluem anticorpos heterófilos, anticorpos endógenos anti-hormônios e outros interferentes das mais variadas origens. Todos estes fatores devem ser analisados em conjunto quando da interpretação de uma dosagem hormonal.
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Abstract
BACKGROUND Bloodspot assays for hormones have advantages of ease of collection/transportation, minimal invasiveness and small blood volume. Such an approach would be of use in epidemiological studies of insulin resistance in children and neonates. METHODS A two-site chemiluminescent immunoassay for the quantitation of insulin in bloodspots dried on filter paper, based on modifications of a commercially available kit, was used. Analysis was carried out on two 3-mm diameter discs punched out from whole blood standards and test samples. RESULTS The detection limit of the assay was 5.9 pmol/l of whole blood, with mean intra-assay CV and mean inter-assay CV being <15% above 24 pmol/l. The mean recovery of added insulin was 83%. Comparison of paired whole bloodspots and serum samples collected simultaneously gave a correlation of 0.89. The bloodspot insulin concentrations were stable in excess of 2 months when stored at -20 degrees C and were not susceptible to degradation after four freeze-thaw cycles. CONCLUSIONS This simple and convenient method is suitable for the measurement of insulin in small volumes of blood collected on filter paper cards and can be applied to epidemiological studies of insulin resistance.
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Affiliation(s)
- N L Butter
- Regional Endocrine Laboratory, Department of Clinical Biochemistry, University Hospital Birmingham NHS Trust, Selly Oak Hospital, Raddlebarn Road, Birmingham B29 6JD, UK
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Sapin R, Le Galudec V, Gasser F, Pinget M, Grucker D. Elecsys Insulin Assay: Free Insulin Determination and the Absence of Cross-Reactivity with Insulin Lispro. Clin Chem 2001. [DOI: 10.1093/clinchem/47.3.602] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Rémy Sapin
- Laboratoire Universitaire de Biophysique, Unité d’Analyses Endocriniennes, CNRS UPRES-A 7004, Université Louis Pasteur, Faculté de Médecine, 67085 Strasbourg Cedex, France
| | - Valérie Le Galudec
- Laboratoire Universitaire de Biophysique, Unité d’Analyses Endocriniennes, CNRS UPRES-A 7004, Université Louis Pasteur, Faculté de Médecine, 67085 Strasbourg Cedex, France
- Service d’Endocrinologie et Diabétologie, Hôpital Civil, 67091 Strasbourg Cedex, France
| | - Françoise Gasser
- Laboratoire Universitaire de Biophysique, Unité d’Analyses Endocriniennes, CNRS UPRES-A 7004, Université Louis Pasteur, Faculté de Médecine, 67085 Strasbourg Cedex, France
| | - Michel Pinget
- Service d’Endocrinologie et Diabétologie, Hôpital Civil, 67091 Strasbourg Cedex, France
| | - Daniel Grucker
- Laboratoire Universitaire de Biophysique, Unité d’Analyses Endocriniennes, CNRS UPRES-A 7004, Université Louis Pasteur, Faculté de Médecine, 67085 Strasbourg Cedex, France
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