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Ruggenthaler M, Grass J, Schuh W, Huber CG, Reischl RJ. Levothyroxine sodium revisited: A wholistic structural elucidation approach of new impurities via HPLC-HRMS/MS, on-line H/D exchange, NMR spectroscopy and chemical synthesis. J Pharm Biomed Anal 2016; 135:140-152. [PMID: 28024262 DOI: 10.1016/j.jpba.2016.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 11/29/2016] [Accepted: 12/01/2016] [Indexed: 11/29/2022]
Abstract
The structural elucidation of unknown pharmaceutical impurities plays an important role in the quality control of newly developed and well-established active pharmaceutical ingredients (APIs). The United States Pharmacopeia (USP) monograph for the API Levothyroxine Sodium, a synthetic thyroid hormone, features two high pressure liquid chromatography (HPLC) methods using UV-VIS absorption detection to determine organic impurities in the drug substance. The impurity profile of the first USP method ("Procedure 1") has already been extensively studied, however for the second method ("Procedure 2"), which exhibits a significantly different impurity profile, no wholistic structural elucidation of impurities has been performed yet. Applying minor modifications to the chromatographic parameters of USP "Procedure 2" and using various comprehensive structural elucidation methods such as high resolution tandem mass spectrometry with on-line hydrogen-deuterium (H/D) exchange or two-dimensional nuclear magnetic resonance spectroscopy (NMR) we gained new insights about the complex impurity profile of the synthetic thyroid hormone. This resulted in the characterization of 24 compounds previously unknown to literature and the introduction of two new classes of Levothyroxine Sodium impurities. Five novel compounds were unambiguously identified via isolation or synthesis of reference substances and subsequent NMR spectroscopic investigation. Additionally, Collision-Induced Dissociation (CID)-type fragmentation of identified major impurities as well as neutral loss fragmentation patterns of many characterized impurities were discussed.
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Affiliation(s)
- M Ruggenthaler
- SANDOZ GmbH, Biochemiestraße 10, A-6250 Kundl/Tirol, Austria; Department of Molecular Biology, Division of Chemistry and Bioanalytics,University of Salzburg, Hellbrunner Straße 34, A-5020 Salzburg, Austria
| | - J Grass
- SANDOZ GmbH, Biochemiestraße 10, A-6250 Kundl/Tirol, Austria
| | - W Schuh
- SANDOZ GmbH, Biochemiestraße 10, A-6250 Kundl/Tirol, Austria
| | - C G Huber
- Department of Molecular Biology, Division of Chemistry and Bioanalytics,University of Salzburg, Hellbrunner Straße 34, A-5020 Salzburg, Austria
| | - R J Reischl
- Department of Molecular Biology, Division of Chemistry and Bioanalytics,University of Salzburg, Hellbrunner Straße 34, A-5020 Salzburg, Austria.
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Aker AM, Watkins DJ, Johns LE, Ferguson KK, Soldin OP, Anzalota Del Toro LV, Alshawabkeh AN, Cordero JF, Meeker JD. Phenols and parabens in relation to reproductive and thyroid hormones in pregnant women. ENVIRONMENTAL RESEARCH 2016; 151:30-37. [PMID: 27448730 PMCID: PMC5071140 DOI: 10.1016/j.envres.2016.07.002] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/31/2016] [Accepted: 07/02/2016] [Indexed: 05/21/2023]
Abstract
INTRODUCTION Phenols and parabens are ubiquitous environmental contaminants. Evidence from animal studies and limited human data suggest they may be endocrine disruptors. In the current study, we examined associations of phenols and parabens with reproductive and thyroid hormones in 106 pregnant women recruited for the prospective cohort, "Puerto Rico Testsite for Exploring Contamination Threats (PROTECT)". METHODS Urinary exposure biomarkers (bisphenol A, triclosan, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, butyl, methyl and propyl paraben) and serum hormone levels (estradiol, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone) were measured at up to two time points during pregnancy (16-20 weeks and 24-28 weeks). We used linear mixed models to assess relationships between exposure biomarkers and hormone levels across pregnancy, controlling for urinary specific gravity, maternal age, BMI and education. In sensitivity analyses, we evaluated cross-sectional relationships between exposure and hormone levels stratified by study visit using linear regression. RESULTS An IQR increase in methyl paraben was associated with a 7.70% increase (95% CI 1.50, 13.90) in SHBG. Furthermore, an IQR increase in butyl paraben as associated with an 8.46% decrease (95% CI 16.92, 0.00) in estradiol, as well as a 9.34% decrease (95% CI -18.31,-0.38) in estradiol/progesterone. Conversely, an IQR increase in butyl paraben was associated with a 5.64% increase (95% CI 1.26, 10.02) in FT4. Progesterone was consistently negatively associated with phenols, but none reached statistical significance. After stratification, methyl and propyl paraben were suggestively negatively associated with estradiol at the first time point (16-20 weeks), and suggestively positively associated with estradiol at the second time point (24-28 weeks). CONCLUSIONS Within this ongoing birth cohort, certain phenols and parabens were associated with altered reproductive and thyroid hormone levels during pregnancy. These changes may contribute to adverse health effects in mothers or their offspring, but additional research is required.
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Affiliation(s)
- Amira M Aker
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Deborah J Watkins
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Lauren E Johns
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Kelly K Ferguson
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Offie P Soldin
- Department of Medicine, Georgetown University, 3900 Reservoir Rd NW, Washington, DC 20007, USA
| | - Liza V Anzalota Del Toro
- University of Puerto Rico Graduate School of Public Health, UPR Medical Sciences Campus, PO Box 365067, San Juan, PR 00936-5067, USA
| | - Akram N Alshawabkeh
- College of Engineering, Northeastern University, 110 Forsyth St, Boston, MA 02115, USA
| | - José F Cordero
- University of Puerto Rico Graduate School of Public Health, UPR Medical Sciences Campus, PO Box 365067, San Juan, PR 00936-5067, USA
| | - John D Meeker
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
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De Angelis M, Giesert F, Finan B, Clemmensen C, Müller TD, Vogt-Weisenhorn D, Tschöp MH, Schramm KW. Determination of thyroid hormones in mouse tissues by isotope-dilution microflow liquid chromatography–mass spectrometry method. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1033-1034:413-420. [DOI: 10.1016/j.jchromb.2016.08.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/19/2016] [Accepted: 08/25/2016] [Indexed: 12/22/2022]
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Abstract
PURPOSE OF REVIEW Hypothyroidism is highly prevalent in chronic kidney disease (CKD) patients, including those receiving dialysis. This review examines potential mechanistic links between thyroid and kidney disease; current evidence for hypothyroidism as a risk factor for de novo CKD and CKD progression; and studies of thyroid functional disorders, cardiovascular disease, and death in the CKD population. RECENT FINDINGS Epidemiologic data have demonstrated an incrementally higher prevalence of hypothyroidism with increasing severity of kidney dysfunction. Various thyroid functional test abnormalities are also commonly observed in CKD due to alterations in thyroid hormone synthesis, metabolism, and regulation. Although the mechanistic link between thyroid and kidney disease remains unclear, observational studies suggest that hypothyroidism is associated with abnormal kidney structure and function. Previously thought to be a physiologic adaptation, recent studies show that hypothyroidism is associated with higher risk of cardiovascular disease and death in CKD. SUMMARY A growing body of evidence suggests that hypothyroidism is a risk factor for incident CKD, CKD progression, and higher death risk in kidney disease patients. Rigorous studies are needed to determine the impact of thyroid hormone replacement upon kidney disease progression, cardiovascular disease, and mortality, which may shed light onto the causal implications of hypothyroidism in CKD.
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Affiliation(s)
- Connie M Rhee
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine School of Medicine, Orange, California, United States
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Chaker L, Korevaar TIM, Medici M, Uitterlinden AG, Hofman A, Dehghan A, Franco OH, Peeters RP. Thyroid Function Characteristics and Determinants: The Rotterdam Study. Thyroid 2016; 26:1195-204. [PMID: 27484151 DOI: 10.1089/thy.2016.0133] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Information on determinants and change of thyroid function over time is sparse and conflicting but crucial for clinical interpretation and research. Therefore, our aim was to systematically investigate determinants of thyroid-stimulating hormone (TSH), free thyroxine (FT4) (as markers of thyroid function), their mutual relation (as marker of thyroid function set point) and changes in thyroid function over time. METHODS We included 9402 participants from the Rotterdam Study not taking thyroid medication and with available thyroid function measurements. Repeated measurements (6.5-year interval) were available for 1225 participants. The association of selected determinants with TSH, FT4, and their mutual relation (reflecting thyroid function set point) was estimated using linear regression models using restricted cubic splines with three knots. The factors investigated were age, sex, body mass index (BMI), tobacco smoking, alcohol use, thyroperoxidase antibodies (TPOAb), and common genetic factors. RESULTS Most influential determinants of TSH were age, smoking, genetic determinants, and TPOAb levels (p < 0.001). For FT4, most influential determinants were age, BMI, sex, genetic determinants and TPOAb levels (p < 0.001). Older age, female sex, and increased TPOAb levels were associated with a stronger relation between TSH and FT4. TSH levels did not change over time, irrespective of age. FT4 levels increased over time, most prominently in those older than 65 years of age (mean increase of 4.5 pmol/L). CONCLUSIONS The main factors that influence the relationship between thyroid hormone and molar concentrations of TSH in our population-based cohort study are age, smoking, BMI, TPOAb levels, and common genetic variants. The set point that determines TSH secretion as it relates to negative thyroid hormone feedback is modified by age, sex and TPOAb positivity. FT4 levels increase over time, with a more pronounced increase in the elderly, while TSH values seem stable over time. Our results question the current notion of an increase of TSH with increasing age.
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Affiliation(s)
- Layal Chaker
- 1 Rotterdam Thyroid Center, Erasmus University Medical Center , Rotterdam, The Netherlands
- 2 Department of Internal Medicine, Erasmus University Medical Center , Rotterdam, The Netherlands
- 3 Department of Epidemiology, Erasmus University Medical Center , Rotterdam, The Netherlands
| | - Tim I M Korevaar
- 1 Rotterdam Thyroid Center, Erasmus University Medical Center , Rotterdam, The Netherlands
- 2 Department of Internal Medicine, Erasmus University Medical Center , Rotterdam, The Netherlands
- 3 Department of Epidemiology, Erasmus University Medical Center , Rotterdam, The Netherlands
| | - Marco Medici
- 1 Rotterdam Thyroid Center, Erasmus University Medical Center , Rotterdam, The Netherlands
- 2 Department of Internal Medicine, Erasmus University Medical Center , Rotterdam, The Netherlands
| | - André G Uitterlinden
- 2 Department of Internal Medicine, Erasmus University Medical Center , Rotterdam, The Netherlands
- 3 Department of Epidemiology, Erasmus University Medical Center , Rotterdam, The Netherlands
| | - Albert Hofman
- 3 Department of Epidemiology, Erasmus University Medical Center , Rotterdam, The Netherlands
- 4 Harvard T.H. Chan School of Public Health , Boston, Massachusetts
| | - Abbas Dehghan
- 3 Department of Epidemiology, Erasmus University Medical Center , Rotterdam, The Netherlands
| | - Oscar H Franco
- 3 Department of Epidemiology, Erasmus University Medical Center , Rotterdam, The Netherlands
| | - Robin P Peeters
- 1 Rotterdam Thyroid Center, Erasmus University Medical Center , Rotterdam, The Netherlands
- 2 Department of Internal Medicine, Erasmus University Medical Center , Rotterdam, The Netherlands
- 3 Department of Epidemiology, Erasmus University Medical Center , Rotterdam, The Netherlands
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Abstract
OBJECTIVE Various physiological changes occur in maternal thyroid economy during pregnancy. This review focuses on the events taking place during gestation that together strongly influence maternal thyroid function. METHODS Scientific reports on maternal thyroid physiology in pregnancy. RESULTS During the 1st trimester, human chorionic gonadotropin (hCG) induces a transient increase in free thyroxine (FT4) levels, which is mirrored by a lowering of thyroid-stimulating hormone (TSH) concentrations. Following this period, serum FT4 concentrations decrease of approximately 10 to 15%, and serum TSH values steadily return to normal. Also starting in early gestation, there is a marked increase in serum thyroxine-binding globulin (TBG) concentrations, which peak around midgestation and are maintained thereafter. This event, in turn, is responsible for a significant rise in total T4 and triiodothyronine (T3). Finally, significant modifications in the peripheral metabolism of maternal thyroid hormones occur, due to the expression and activity of placental types 2 and 3 iodothyronine deiodinases (D2 and D3, respectively). CONCLUSION In line with these variations, both free thyroid hormone and TSH reference intervals change throughout pregnancy, and most scientific societies now recommend that method- and gestation-specific reference ranges be used for interpreting results in pregnancy.The maternal iodide pool reduces during pregnancy because of increased renal clearance of iodine and transfer of iodine to the feto-placental unit. This results in an additional requirement of iodine during pregnancy of ~100% as compared to nonpregnant adults. In accordance, the recommended iodine intake in pregnancy is 250 μg/day. A daily iodine intake below this threshold poses risks of various degrees of thyroid insufficiency for both the mother and the fetus.
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Affiliation(s)
- Mariacarla Moleti
- Dipartimento di Medicina Clinica e Sperimentale, University of Messina, Messina, Italy
| | - Francesco Trimarchi
- Dipartimento di Medicina Clinica e Sperimentale, University of Messina, Messina, Italy
| | - Francesco Vermiglio
- Dipartimento di Medicina Clinica e Sperimentale, University of Messina, Messina, Italy
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Masika LS, Zhao Z, Soldin SJ. Is measurement of TT3 by immunoassay reliable at low concentrations? A comparison of the Roche Cobas 6000 vs. LC–MSMS. Clin Biochem 2016. [DOI: 10.1016/j.clinbiochem.2016.02.004 pmid: 26879528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
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Quantification of 11 thyroid hormones and associated metabolites in blood using isotope-dilution liquid chromatography tandem mass spectrometry. Anal Bioanal Chem 2016; 408:5429-42. [DOI: 10.1007/s00216-016-9614-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 04/24/2016] [Accepted: 04/29/2016] [Indexed: 12/26/2022]
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Hansen M, Luong X, Sedlak DL, Helbing CC, Hayes T. Quantification of 11 thyroid hormones and associated metabolites in blood using isotope-dilution liquid chromatography tandem mass spectrometry. Anal Bioanal Chem 2016. [DOI: 10.1007/s00216-016-9614-9 pubmed pmid: 27215639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
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Abstract
INTRODUCTION Hypothyroidism is currently a condition that can be treated, but not cured. Although levothyroxine reverses stigmata of hypothyroidism in most individuals, some patients feel dissatisfied with 'monotherapy', and this has stimulated interest in 'combination therapy' with both levothyroxine and liothyronine. AREAS COVERED A search of PubMed was conducted using terms including hypothyroidism, treatment, benefits, risks, and safety. Based on the articles identified, the body of evidence regarding the efficacy of traditional levothyroxine is reviewed. Concerns with levothyroxine therapy including impaired quality of life in treated patients, thyroxine-predominant hormone ratios, and inadvertent iatrogenic thyroid disease are discussed. The trials of combination therapy performed since 1999 were reviewed. The heterogeneity of these trials, both in terms of design and results, is discussed. The potential for new trials to determine whether combination therapy can reverse the dissatisfaction associated with monotherapy, while avoiding non-physiologic hormone ratios, inadvertent thyrotoxicosis, and unacceptable side effects is discussed. Expert commentary: Research regarding which therapy fully reverses hypothyroidism at a tissue and cellular level is ongoing. The field would be advanced by the development of an extended release preparation of liothyronine. In the future regeneration of functional thyroid follicles from stem cells may offer hope for curing hypothyroidism.
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Donzelli R, Colligiani D, Kusmic C, Sabatini M, Lorenzini L, Accorroni A, Nannipieri M, Saba A, Iervasi G, Zucchi R. Effect of Hypothyroidism and Hyperthyroidism on Tissue Thyroid Hormone Concentrations in Rat. Eur Thyroid J 2016; 5:27-34. [PMID: 27099836 PMCID: PMC4836127 DOI: 10.1159/000443523] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 12/17/2015] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND OBJECTIVE The present study was aimed at determining the effects of experimental hypothyroidism and hyperthyroidism on tissue thyroid hormones by a mass spectrometry-based technique. METHODS Rats were subjected to propylthiouracil treatment or administration of exogenous triiodothyronine (T3) or thyroxine (T4). Tissue T3 and T4 were measured by liquid chromatography tandem mass spectrometry in the heart, liver, kidney, visceral and subcutaneous adipose tissue, and brain. RESULTS Baseline tissue T3 and T4 concentrations ranged from 0.2 to 20 pmol ∙ g(-1) and from 3 to 125 pmol ∙ g(-1), respectively, with the highest values in the liver and kidney, and the lowest values in the adipose tissue. The T3/T4 ratio (expressed as a percentage) was in the 7-20% range in all tissues except the brain, where it averaged 75%. In hypothyroidism, tissue T3 was more severely reduced than serum free T3, averaging 1-6% of the baseline versus 30% of the baseline. The extent of tissue T3 reduction, expressed as percentage of the baseline, was not homogeneous (p < 0.001), with liver = kidney > brain > heart > adipose tissue. The tissue T3/T4 ratio significantly increased in all organs except the kidney, averaging 330% in the brain and 50-90% in the other tissues. By contrast, exogenous T3 and T4 administration produced similar increases in serum free T3 and in tissue T3, and the relative changes were not significantly different between different tissues. CONCLUSIONS While the response to increased thyroid hormones availability was similar in all tissues, decreased thyroid hormone availability induced compensatory responses, leading to a significant mismatch between changes in serum and in specific tissues.
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Affiliation(s)
| | - Daria Colligiani
- Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | | | | | | | - Alice Accorroni
- Departments of Pathology, University of Pisa, Pisa, Italy
- Scuola Superiore Sant'Anna, Pisa, Italy
| | | | | | | | - Riccardo Zucchi
- Departments of Pathology, University of Pisa, Pisa, Italy
- *Riccardo Zucchi, MD, PhD, Laboratory of Biochemistry, Department of Pathology, University of Pisa, via Roma 55, IT-56126 Pisa (Italy), E-Mail
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Is measurement of TT3 by immunoassay reliable at low concentrations? A comparison of the Roche Cobas 6000 vs. LC-MSMS. Clin Biochem 2016; 49:846-9. [PMID: 26879528 DOI: 10.1016/j.clinbiochem.2016.02.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 02/05/2016] [Accepted: 02/10/2016] [Indexed: 11/21/2022]
Abstract
OBJECTIVES Thyroid dysfunction is a common medical condition affecting an estimated 30 million people in the US alone. Employing gold standard Liquid chromatography-tandem mass spectrometry (LC-MSMS) methods we have examined the extent of inaccuracy of immunoassay (IA) measurement for total T3 (TT3) at low, normal and high concentrations. DESIGN AND METHODS 268 TT3 Roche Cobas 6000 immunoassay TT3 values (covering the low, normal, and high ranges) were compared with LC-MSMS results. RESULTS At TT3 concentrations between 50 and 113ng/dL (conversion factor for TT3 to SI Units is ng/dL×0.0154=nmol/L), n=122, LC-MSMS values were lower than immunoassay with 72% found to be below the 2.5th percentile by LC-MSMS compared to 27% for immunoassay. Strikingly 45% of the patients classified as normal TT3 by immunoassay were defined as lower than the 2.5th percentile by LC-MSMS. Only 38 of the 122 patients with low T3's were not receiving T4. In this latter group all of whom had TSH's>3.7mIU/L, 74% of results by LC-MSMS were below the 2.5th percentile while only 21% were below the 2.5th percentile by IA. The clinical consequences of these inaccuracies may affect whether dosing with T4 or combination of T4 with T3 is selected for treatment. Finally the correlation of TT3 with TSH was far superior when TT3 was measured by LC-MSMS. A typical case which demonstrates our message is included. CONCLUSION T3 being the active hormone needs to be reliably measured and if the patient has low TT3 and hypothyroid symptoms persist; treatment with T3 should be considered. A typical case report is included to illustrate the problems of inaccurate immunoassay results for TT3. Measurement of TT3 by immunoassay at low concentrations is less than optimal and often provides the clinician with a normal result when the LC-MSMS method and the patient's clinical condition suggests that supplementation with T3 (as in combination therapy) may be required to optimize patient care.
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Xing J, Yuan E, Li J, Zhang Y, Meng X, Zhang X, Rong S, Lv Z, Tian Y, Jia L. Trimester- and Assay-Specific Thyroid Reference Intervals for Pregnant Women in China. Int J Endocrinol 2016; 2016:3754213. [PMID: 27087808 PMCID: PMC4819108 DOI: 10.1155/2016/3754213] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 11/17/2022] Open
Abstract
Objective. The guidelines of the American Thyroid Association (ATA) recommend an upper limit reference interval (RI) of thyroid stimulating hormone (TSH) of 2.5 mIU/L in the first trimester of pregnancy and 3.0 mIU/L in subsequent trimesters, but some reported ranges in China are significantly higher. Our study aimed to establish trimester- and assay-specific RIs for thyroid hormones in normal pregnant Chinese women. Methods. In this cross-sectional study, 2540 women with normal pregnancies (first trimester, n = 398; second trimester, n = 797; third trimester, n = 1345) and 237 healthy nonpregnant control subjects were recruited. Serum TSH, free thyroxin (FT4), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) levels were determined by automated chemiluminescence with an Immulite 2000 system (Siemens, Erlangen, Germany). After outliers were excluded, the 2.5-97.5th percentiles were used to define the RIs. Results. The RIs of thyroid function in the first, second, and third trimesters of pregnancy and in nonpregnant controls were 0.07-3.96, 0.27-4.53, 0.48-5.40, and 0.69-5.78 mIU/L for TSH and 9.16-18.12, 8.67-16.21, 7.80-13.90, and 8.24-16.61 pmol/L for FT4, respectively. Conclusion. The trimester- and assay-specific RIs of thyroid function during pregnancy differed between trimesters, which suggests that it is advisable to detect and avoid misclassification of thyroid dysfunction during pregnancy for women in Henan, China.
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Affiliation(s)
- Jinfang Xing
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Enwu Yuan
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Jing Li
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Yuchao Zhang
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Xiangying Meng
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Xia Zhang
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Shouhua Rong
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Zhongxing Lv
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Yuan Tian
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
| | - Liting Jia
- Clinical Laboratory Department, The Third Affiliated Hospital of Zhengzhou University, No. 7 Front Kangfu Street, Er'qi Distric, Zhengzhou 450052, China
- *Liting Jia:
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Analysis of free drug fractions in human serum by ultrafast affinity extraction and two-dimensional affinity chromatography. Anal Bioanal Chem 2015; 408:131-40. [PMID: 26462924 DOI: 10.1007/s00216-015-9082-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 09/19/2015] [Accepted: 09/24/2015] [Indexed: 12/12/2022]
Abstract
Ultrafast affinity extraction and a two-dimensional high performance affinity chromatographic system were used to measure the free fractions for various drugs in serum and at typical therapeutic concentrations. Pooled samples of normal serum or serum from diabetic patients were utilized in this work. Several drug models (i.e., quinidine, diazepam, gliclazide, tolbutamide, and acetohexamide) were examined that represented a relatively wide range of therapeutic concentrations and affinities for human serum albumin (HSA). The two-dimensional system consisted of an HSA microcolumn for the extraction of a free drug fraction, followed by a larger HSA analytical column for the further separation and measurement of this fraction. Factors that were optimized in this method included the flow rates, column sizes, and column switching times that were employed. The final extraction times used for isolating the free drug fractions were 333-665 ms or less. The dissociation rate constants for several of the drugs with soluble HSA were measured during system optimization, giving results that agreed with reference values. In the final system, free drug fractions in the range of 0.7-9.5% were measured and gave good agreement with values that were determined by ultrafiltration. Association equilibrium constants or global affinities were also estimated by this approach for the drugs with soluble HSA. The results for the two-dimensional system were obtained in 5-10 min or less and required only 1-5 μL of serum per injection. The same approach could be adapted for work with other drugs and proteins in clinical samples or for biomedical research.
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Rathmann D, Rijntjes E, Lietzow J, Köhrle J. Quantitative Analysis of Thyroid Hormone Metabolites in Cell Culture Samples Using LC-MS/MS. Eur Thyroid J 2015; 4:51-8. [PMID: 26601073 PMCID: PMC4640291 DOI: 10.1159/000430840] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 04/20/2015] [Indexed: 12/16/2022] Open
Abstract
A liquid-liquid extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) method to determine iodothyronines and thyronamines (TAM) from cell culture media was developed. Thyroid hormones (TH) are metabolized by sequential deiodination to eventually yield thyronine (T0), but can also be decarboxylated, resulting in TAM. The method presented here for extraction of DMEM/F12 cell culture media is a fundamental procedure for a precise determination of 9 TH and 6 TAM from a single LC run. Analytes and internal standards (IS) were extracted from DMEM/F12 (w/o phenol red) by liquid-liquid extraction using isopropanol-TBME (30:70 v/v). Measurement of TH and TAM was performed during a 10-min run time using (13)C6-T4, (13)C6-T3, (13)C6-rT3, (13)C6-3,3'T2 and (2)H4-T1AM as IS. Calibration curves covered 11 calibrators measured as triplicates each for the analysis of the 9 TH and 6 TAM metabolites, and the 5 IS were linear and reproducible in the range of 0.12-120 nM (R(2) 0.991-0.999) for all calibrators. The lower limit of quantification was 0.078-0.234 nM. Method validation and robustness were demonstrated by the analysis of precision, accuracy, process efficiency, matrix effects and recoveries, as well as intra- and interassay stability. These parameters were investigated for high, middle and low concentrations of quality controls of all 9 TH and 6 TAM metabolites. This validated, sensitive and interaction-free LC-MS/MS method allows rapid analysis and accurate determination of TH and TAM from DMEM/F12 (w/o phenol red) conditioned media and seems to be easily transferable and applied to commonly used buffers and cell culture media.
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Affiliation(s)
| | | | | | - Josef Köhrle
- *Prof. Dr. Josef Köhrle, Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, DE-13353 Berlin (Germany), E-Mail
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Rhee CM, Brent GA, Kovesdy CP, Soldin OP, Nguyen D, Budoff MJ, Brunelli SM, Kalantar-Zadeh K. Thyroid functional disease: an under-recognized cardiovascular risk factor in kidney disease patients. Nephrol Dial Transplant 2015; 30:724-37. [PMID: 24574542 PMCID: PMC4425477 DOI: 10.1093/ndt/gfu024] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 01/17/2014] [Indexed: 01/07/2023] Open
Abstract
Thyroid functional disease, and in particular hypothyroidism, is highly prevalent among chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. In the general population, hypothyroidism is associated with impaired cardiac contractility, endothelial dysfunction, atherosclerosis and possibly higher cardiovascular mortality. It has been hypothesized that hypothyroidism is an under-recognized, modifiable risk factor for the enormous burden of cardiovascular disease and death in CKD and ESRD, but this has been difficult to test due to the challenge of accurate thyroid functional assessment in uremia. Low thyroid hormone levels (i.e. triiodothyronine) have been associated with adverse cardiovascular sequelae in CKD and ESRD patients, but these metrics are confounded by malnutrition, inflammation and comorbid states, and hence may signify nonthyroidal illness (i.e. thyroid functional test derangements associated with underlying ill health in the absence of thyroid pathology). Thyrotropin is considered a sensitive and specific thyroid function measure that may more accurately classify hypothyroidism, but few studies have examined the clinical significance of thyrotropin-defined hypothyroidism in CKD and ESRD. Of even greater uncertainty are the risks and benefits of thyroid hormone replacement, which bear a narrow therapeutic-to-toxic window and are frequently prescribed to CKD and ESRD patients. In this review, we discuss mechanisms by which hypothyroidism adversely affects cardiovascular health; examine the prognostic implications of hypothyroidism, thyroid hormone alterations and exogenous thyroid hormone replacement in CKD and ESRD; and identify areas of uncertainty related to the interplay between hypothyroidism, cardiovascular disease and kidney disease requiring further investigation.
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Affiliation(s)
- Connie M. Rhee
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA
| | - Gregory A. Brent
- Department of Medicine, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
- Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Csaba P. Kovesdy
- Division of Nephrology, Memphis Veterans Affairs Medical Center, Memphis, TN, USA
- Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Offie P. Soldin
- Department of Medicine, Georgetown University Medical Center, Washington, DC, USA
| | - Danh Nguyen
- Department of Medicine, University of California Irvine, Orange, CA, USA
| | - Matthew J. Budoff
- Division of Cardiology, LA Biomedical Research Institute, Harbor-UCLA Medical Center, Los Angeles, CA, USA
| | - Steven M. Brunelli
- Division of Nephrology, Brigham and Women's Hospital, Boston, MA, USA
- DaVita Clinical Research, Minneapolis, MN, USA
| | - Kamyar Kalantar-Zadeh
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA
- Department of Medicine, University of California Irvine, Orange, CA, USA
- Department of Epidemiology, UCLA School of Public Health, Los Angeles, CA, USA
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Wang Z, Wang Y, Lv F, Liu X, Jia C, Chen X, Han T. An Effective Method for Monitoring Three Iodothyronines in Meat Tissue and Eggs by Liquid Chromatography–Tandem Mass Spectrometry. FOOD ANAL METHOD 2015. [DOI: 10.1007/s12161-015-0091-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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69
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Johns LE, Ferguson KK, Soldin OP, Cantonwine DE, Rivera-González LO, Del Toro LVA, Calafat AM, Ye X, Alshawabkeh AN, Cordero JF, Meeker JD. Urinary phthalate metabolites in relation to maternal serum thyroid and sex hormone levels during pregnancy: a longitudinal analysis. Reprod Biol Endocrinol 2015; 13:4. [PMID: 25596636 PMCID: PMC4326411 DOI: 10.1186/1477-7827-13-4] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 01/12/2015] [Indexed: 10/28/2022] Open
Abstract
BACKGROUND Increasing scientific evidence suggests that exposure to phthalates during pregnancy may be associated with an elevated risk of adverse reproductive outcomes such as preterm birth. Maternal endocrine disruption across pregnancy may be one pathway mediating some of these relationships. We investigated whether urinary phthalate metabolites were associated with maternal serum thyroid (free thyroxine [FT4], free triiodothyronine [FT3], and thyroid-stimulating hormone [TSH]), and sex (estradiol, progesterone, and sex hormone-binding globulin [SHBG]) hormone levels at multiple time points during pregnancy. METHODS Preliminary data (n = 106) were obtained from an ongoing prospective birth cohort in Northern Puerto Rico. We collected urine and serum sample at the first and third study visits that occurred at 18 +/- 2 and 26 +/- 2 weeks of gestation, respectively. To explore the longitudinal relationships between urinary phthalate metabolites and serum thyroid and sex hormone concentrations, we used linear mixed models (LMMs) adjusted for prepregnancy body mass index (BMI) and maternal age. An interaction term was added to each LMM to test whether the effect of urinary phthalate metabolites on serum thyroid and sex hormone levels varied by study visit. In cross-sectional analyses, we stratified BMI- and age-adjusted linear regression models by study visit. RESULTS In adjusted LMMs, we observed significant inverse associations between mono-3-carboxypropyl phthalate (MCPP) and FT3 and between mono-ethyl phthalate (MEP) and progesterone. In cross-sectional analyses by study visit, we detected stronger and statistically significant inverse associations at the third study visit between FT3 and MCPP as well as mono-carboxyisooctyl phthalate (MCOP); also at the third study visit, significant inverse associations were observed between FT4 and metabolites of di-(2-ethylhexyl) phthalate (DEHP). The inverse association between MEP and progesterone was consistent across study visits. CONCLUSIONS In this group of pregnant women, urinary phthalate metabolites may be associated with altered maternal serum thyroid and sex hormone levels, and the magnitude of these effects may depend on the timing of exposure during gestation.
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Affiliation(s)
- Lauren E Johns
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI USA
| | - Kelly K Ferguson
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI USA
| | - Offie P Soldin
- Department of Medicine, Georgetown University, Washington, DC USA
| | - David E Cantonwine
- Department of Obstetrics and Gynecology, Brigham and Women’s Hospital, Boston, MA USA
| | - Luis O Rivera-González
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI USA
| | - Liza V Anzalota Del Toro
- University of Puerto Rico Graduate School of Public Health, UPR Medical Sciences Campus, San Juan, Puerto Rico
| | | | - Xiaoyun Ye
- Centers for Disease and Control and Prevention, Atlanta, GA USA
| | | | - José F Cordero
- University of Puerto Rico Graduate School of Public Health, UPR Medical Sciences Campus, San Juan, Puerto Rico
| | - John D Meeker
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI USA
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Abstract
IMPORTANCE Subclinical hypothyroidism (SCH) is a common clinical entity with a putative role in a wide range of disorders. The impact of SCH on mortality and markers of morbidity has been demonstrated, but studies have shown inconsistent results. Evidence regarding the effect of levothyroxine treatment on reversing morbidity markers is emerging, but the value of treatment is still unclear. OBJECTIVE The objectives of this review were to assess recent, high-quality studies evaluating the role of SCH in cardiovascular health, cognition, mood, pregnancy, anemia, and renal disease; to examine the effects of levothyroxine on reducing mortality or reversing markers of morbidity in these conditions; and to consider how new research insights may help guide clinical practice. EVIDENCE REVIEW A PubMed search was conducted (using 'subclinical hypothyroidism' [Title/Abstract] AND morbidity [MeSH Subheading] as search criteria) and was restricted to human studies published in the English language between 1990 and 2013. Subsequent searches of retrieved articles yielded further studies, which were included based on quality. Emphasis was given to large observational studies, well-conducted meta-analyses, and randomized controlled trials. FINDINGS The difficulty of diagnosing SCH, particularly in the elderly, may underlie many of the conflicting results seen in the literature. Increased understanding of the at-risk patient population will result in better selection of study subjects and, likely, unequivocal results. Regardless of the current confusion, emerging evidence suggests that certain markers of morbidity are reversed by levothyroxine therapy across the disorders examined here. CONCLUSION AND RELEVANCE Future large, well-controlled studies will not only clarify the role of SCH but also help identify patients for whom levothyroxine treatment will provide the most benefit.
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Affiliation(s)
- James V Hennessey
- Department of Medicine, Division of Endocrinology, Beth Israel Deaconess Medical Center , Boston, MA , USA
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Zheng X, Matsuda R, Hage DS. Analysis of free drug fractions by ultrafast affinity extraction: interactions of sulfonylurea drugs with normal or glycated human serum albumin. J Chromatogr A 2014; 1371:82-9. [PMID: 25456590 PMCID: PMC4254497 DOI: 10.1016/j.chroma.2014.10.092] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/04/2014] [Accepted: 10/24/2014] [Indexed: 02/08/2023]
Abstract
Ultrafast affinity extraction and a multi-dimensional affinity system were developed for measuring free drug fractions at therapeutic levels. This approach was used to compare the free fractions and global affinity constants of several sulfonylurea drugs in the presence of normal human serum albumin (HSA) or glycated forms of this protein, as are produced during diabetes. Affinity microcolumns containing immobilized HSA were first used to extract the free drug fractions in injected drug/protein mixtures. As the retained drug eluted from the HSA microcolumn, it was passed through a second HSA column for further separation and measurement. Items that were considered during the optimization of this approach included the column sizes and flow rates that were used, and the time at which the second column was placed on-line with the HSA microcolumn. This method required only 1.0 μL of a sample per injection and was able to measure free drug fractions as small as 0.09-2.58% with an absolute precision of ±0.02-0.5%. The results that were obtained indicated that glycation can affect the free fractions of sulfonylurea drugs at typical therapeutic levels and that the size of this effect varies with the level of HSA glycation. Global affinity constants that were estimated from these free drug fractions gave good agreement with those predicted from previous binding studies or determined through a reference method. The same approach could be utilized with other drugs and proteins or modified binding agents of clinical or pharmaceutical interest.
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Affiliation(s)
- Xiwei Zheng
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA
| | - Ryan Matsuda
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA
| | - David S Hage
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA.
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Abdalla SM, Bianco AC. Defending plasma T3 is a biological priority. Clin Endocrinol (Oxf) 2014; 81:633-41. [PMID: 25040645 PMCID: PMC4699302 DOI: 10.1111/cen.12538] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/03/2014] [Accepted: 06/27/2014] [Indexed: 12/16/2022]
Abstract
Triiodothyronine (T3), the active form of thyroid hormone is produced predominantly outside the thyroid parenchyma secondary to peripheral tissue deiodination of thyroxine (T4), with <20% being secreted directly from the thyroid. In healthy individuals, plasma T3 is regulated by the negative feedback loop of the hypothalamus-pituitary-thyroid axis and by homoeostatic changes in deiodinase expression. Therefore, with the exception of a minimal circadian rhythmicity, serum T3 levels are stable over long periods of time. Studies in rodents indicate that different levels of genetic disruption of the feedback mechanism and deiodinase system are met with increase in serum T4 and thyroid-stimulating hormone (TSH) levels, while serum T3 levels remain stable. These findings have focused attention on serum T3 levels in patients with thyroid disease, with important clinical implications affecting therapeutic goals and choice of therapy for patients with hypothyroidism. Although monotherapy with levothyroxine is the standard of care for hypothyroidism, not all patients normalize serum T3 levels with many advocating for combination therapy with levothyroxine and liothyronine. The latter could be relevant for a significant number of patients that remain symptomatic on monotherapy with levothyroxine, despite normalization of serum TSH levels.
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Affiliation(s)
- Sherine M Abdalla
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Rush University Medical Center, Chicago, IL, USA
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Adaway JE, Keevil BG, Owen LJ. Liquid chromatography tandem mass spectrometry in the clinical laboratory. Ann Clin Biochem 2014; 52:18-38. [DOI: 10.1177/0004563214557678] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Clinical laboratory medicine has seen the introduction and evolution of liquid chromatography tandem mass spectrometry in routine clinical laboratories over the last 10–15 years. There still exists a wide diversity of assays from very esoteric and highly specialist manual assays to more simplified kit-based assays. The technology is not static as manufacturers are continually making improvements. Mass spectrometry is now commonly used in several areas of diagnostics including therapeutic drug monitoring, toxicology, endocrinology, paediatrics and microbiology. Some of the most high throughput analyses or common analytes include vitamin D, immunosuppressant monitoring, androgen measurement and newborn screening. It also offers flexibility for the measurement of analytes in a variety of different matrices which would prove difficult with immunoassays. Unlike immunoassays or high-pressure liquid chromatography assays using ultraviolet or fluorescence detection, mass spectrometry offers better specificity and reduced interferences if attention is paid to potential isobaric compounds. Furthermore, multiplexing, which enables multiple analytes to be measured with the same volume of serum is advantageous, and the requirement for large sample volumes is decreasing as instrument sensitivity increases. There are many emerging applications in the literature. Using mass spectrometry to identify novel isoforms or modified peptides is possible as is quantification of proteins and peptides, with or without protein digests. Future developments by the manufacturers may also include mechanisms to improve the throughput of samples and strategies to decrease the level of skill required by the operators.
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Affiliation(s)
- Joanne E Adaway
- Biochemistry Department, University Hospital of South Manchester, Manchester, UK
- Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Brian G Keevil
- Biochemistry Department, University Hospital of South Manchester, Manchester, UK
- Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Laura J Owen
- Biochemistry Department, University Hospital of South Manchester, Manchester, UK
- Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
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Webster GM, Venners SA, Mattman A, Martin JW. Associations between perfluoroalkyl acids (PFASs) and maternal thyroid hormones in early pregnancy: a population-based cohort study. ENVIRONMENTAL RESEARCH 2014; 133:338-47. [PMID: 25019470 DOI: 10.1016/j.envres.2014.06.012] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Revised: 05/09/2014] [Accepted: 06/11/2014] [Indexed: 05/18/2023]
Abstract
BACKGROUND Associations between perfluoroalkyl acids (PFASs) and human thyroid hormone levels remain unclear, especially during early pregnancy when small changes in maternal thyroid hormones can affect fetal brain development. OBJECTIVES To examine associations between maternal serum PFAS levels and maternal thyroid hormone levels in the early 2nd trimester of pregnancy. METHODS Participants were euthyroid pregnant women (n=152) enrolled in the Chemicals, Health and Pregnancy (CHirP) study based in Vancouver, Canada. Associations between maternal serum PFASs, including perfluorohexanesulfonate (PFHxS), perfluorononanoate (PFNA), perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) and repeated measures of maternal thyroid hormones, including free thyroxine (fT4), total thyroxine (TT4) and thyroid stimulating home (TSH) were examined using mixed effects linear models. Associations were considered in all women, then separately in women with high (≥ 9 IU/mL) vs normal (<9 IU/mL) levels of thyroid peroxidase antibody (TPOAb), a marker of autoimmune hypothyroidism (Hashimoto's disease). RESULTS Median PFAS concentrations (ng/mL) in maternal sera were 1.0 (PFHxS), 0.6 (PFNA), 1.7 (PFOA) and 4.8 (PFOS). PFASs were not associated with fT4, TT4 or TSH among women with normal TPOAb. However, among the 9% of women with high TPOAb (n=14), interquartile range (IQR) increases of PFASs were associated with a 46-69% increase in maternal TSH (95% CIs ranging from 8% to 123%) (PFNA, PFOA and PFOS only), and with a 3% to 7% decrease in maternal fT4 (95% CIs ranging from -18% to 5%) (all 4 PFASs). PFNA was also associated with higher maternal TSH in the whole sample. CONCLUSIONS PFASs were positively associated with TSH, and weakly negatively associated with fT4 in the subset of pregnant women with high TPOAb, which occurs in 6-10% of pregnancies. PFASs may exacerbate the already high TSH and low fT4 levels in these women during early pregnancy, which is a critical time of thyroid hormone-mediated fetal brain development. The clinical significance of these findings is not clear. We propose a "multiple hit hypothesis" to explain these findings; this hypothesis deserves evaluation in larger, more representative study samples.
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Affiliation(s)
- Glenys M Webster
- Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6; Child and Family Research Institute, BC Children's and Women's Hospital, 950 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4.
| | - Scott A Venners
- Child and Family Research Institute, BC Children's and Women's Hospital, 950 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4.
| | - Andre Mattman
- Department of Pathology and Laboratory Medicine, St Paul׳s Hospital, 1081 Burrard Street, Vancouver, BC, Canada V6Z 1Y6.
| | - Jonathan W Martin
- Division of Analytical & Environmental Toxicology, Department of Laboratory Medicine & Pathology, University of Alberta, 10-102 Clinical Sciences Bluiding, Edmonton, AB, Canada T6G 2G3.
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75
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Validated ultra high performance liquid chromatography-tandem mass spectrometry method for quantitative analysis of total and free thyroid hormones in bovine serum. J Chromatogr A 2014. [DOI: 10.1016/j.chroma.2014.04.032 pmid: 24786658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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76
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Validated ultra high performance liquid chromatography-tandem mass spectrometry method for quantitative analysis of total and free thyroid hormones in bovine serum. J Chromatogr A 2014; 1345:164-73. [DOI: 10.1016/j.chroma.2014.04.032] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 03/12/2014] [Accepted: 04/10/2014] [Indexed: 11/22/2022]
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77
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Haddow JE. Preventing, identifying and managing thyroid deficiency in prenatal practice. ACTA ACUST UNITED AC 2014. [DOI: 10.1586/eog.13.16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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78
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Integrated Genomics Approaches in Evolutionary and Ecological Endocrinology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 781:299-319. [DOI: 10.1007/978-94-007-7347-9_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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79
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Abstract
Currently, chromatography (GC but more commonly HPLC) is the analytical method of choice for several hormones, either because the immunoassays suffer from extensive crossreactivity or because chromatography permits simultaneous measurements of hormones. However, sometimes the conventional detection systems with HPLC methods do not meet desired specificity. With the increase of robust and affordable LC–MS/MS systems, the next step forward in specificity was taken. LC–MS/MS is rapidly being incorporated in the endocrine laboratories. To be useful in the clinical diagnostic practice, it is of utmost importance that methods are both analytically and clinically vaidated, as until now, the majority of applications of LC–MS/MS in the clinical laboratories are ‘home-made’ methods, therefore special case must be taken. This review aims to focus on Clinical and Laboratory Standards Institute or comparable validated LC–MS/MS methods for targeted hormone analysis used for diagnostic purposes in human samples, published in the last 5 years.
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80
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Abstract
Timely diagnosis and treatment of thyroid dysfunction is compelling given the prevalence and severity of the disease. It requires reliance on adequate laboratory testing of serum TSH as a hallmark in combination with free thyroxine/triiodothyronine. Free hormone methods have to accommodate variations in the concentration and binding capacity of binding proteins. This is a challenge because none of the methodologies developed so far measures the actual unbound hormone in serum. The indirect methods provide an approximation while the direct ones estimate the free hormone concentration either in the presence of the protein-bound counterpart, or after physical separation of the free from bound fraction. The ongoing controversy on the validity and lack of comparability of methodologies points to their imperfectness to reflect real in-vivo free hormone concentrations. Therefore, laboratories and clinicians should know the window of validity and limitations of their methods. The recently developed reference measurement system is a key advance towards improved standardization and clinical validity of free thyroid hormone measurements.
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Affiliation(s)
- Linda M Thienpont
- Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, 9000 Gent, Belgium.
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81
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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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83
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Neu V, Bielow C, Schneider P, Reinert K, Stuppner H, Huber CG. Investigation of reaction mechanisms of drug degradation in the solid state: a kinetic study implementing ultrahigh-performance liquid chromatography and high-resolution mass spectrometry for thermally stressed thyroxine. Anal Chem 2013; 85:2385-90. [PMID: 23311729 DOI: 10.1021/ac303404e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A reaction scheme was derived for the thermal degradation of thyroxine in the solid state, using data obtained from ultrahigh-performance liquid chromatography and high-resolution mass spectrometry (UHPLC-HRMS). To study the reaction mechanism and kinetics of the thermal degradation of the pharmaceutical in the solid state, a workflow was developed by generating compound-specific, time-dependent degradation or formation curves of at least 13 different degradation products. Such curves allowed one to distinguish between first- and second-generation degradation products, as well as impurities resulting from chemical synthesis. The structures of the degradation products were derived from accurate molecular masses and multistage mass spectrometry. Deiodination and oxidative side chain degradation were found to be the major degradation reactions, resulting in the formation of deiodinated thyroxines, as well as acetic acid, benzoic acid, formaldehyde, acetamide, hydroxyacetic acid, oxoacetic acid, hydroxyacetamide, or oxoacetamide derivatives of thyroxine or deiodinated thyroxine. Upon additional structural verification of mass spectrometric data using nuclear magnetic resonance spectroscopy, this comprehensive body of data sheds light on an elaborate, radical-driven reaction scheme, explaining the presence or formation of impurities in thermally stressed thyroxine.
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Affiliation(s)
- Volker Neu
- Department of Molecular Biology, Division of Chemistry and Bioanalytics, University of Salzburg, Hellbrunner Strasse 34, 5020 Salzburg, Austria
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84
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Männistö T. Is there enough evidence of poor fetal growth to merit narrowing free T4 reference ranges during pregnancy? J Clin Endocrinol Metab 2013; 98:43-4. [PMID: 23293336 PMCID: PMC3537104 DOI: 10.1210/jc.2012-4010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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85
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van Deventer HE, Soldin SJ. The expanding role of tandem mass spectrometry in optimizing diagnosis and treatment of thyroid disease. Adv Clin Chem 2013; 61:127-52. [PMID: 24015601 DOI: 10.1016/b978-0-12-407680-8.00005-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This review discusses the state-of-the-art measurement of free and total thyroid hormones in clinical laboratories. We highlight some of the limitations of currently used immunoassays and critically discuss physical separation methods for the measurement of free thyroid hormone. Physical separation methods, such as equilibrium dialysis or ultrafiltration, followed by tandem mass spectrometry for the measurement of free thyroid hormones offer many advantages, which we feel, can deepen our understanding of thyroid hormone metabolism and improve patient diagnosis and care. Problems with direct analogue immunoassay methods for FT4/FT3 as well as immunoassay methods for total T3 at low T3 concentrations and during pregnancy are highlighted. Improved diagnosis and patient management can be achieved utilizing tandem mass spectrometry for these measurements.
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Abstract
Mass spectrometry methods have the potential to measure different hormones during the same analysis and have improved specificity and a wide analytical range compared with many immunoassay methods. Increasingly in clinical laboratories liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays are replacing immunoassays for the routine measurement of testosterone, 17-hydroxyprogesterone, and other steroid hormones. Reference LC-MS/MS methods for steroid, thyroid, and peptide hormones are being used for assessment of the performance and calibration of commercial immunoassays. In this chapter, the general principles of tandem mass spectrometry and examples of hormone assays are described.
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Affiliation(s)
- Helen P Field
- Department of Specialist Laboratory Medicine, St. James's University Hospital, Leeds, UK
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87
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Loh TP, Kao SL, Halsall DJ, Toh SAES, Chan E, Ho SC, Tai ES, Khoo CM. Macro-thyrotropin: a case report and review of literature. J Clin Endocrinol Metab 2012; 97:1823-8. [PMID: 22466337 DOI: 10.1210/jc.2011-3490] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
CONTEXT Isolated elevation of TSH in the absence of thyroid symptoms can be very rarely caused by a macromolecule formed between TSH and Ig (macro-TSH), confounding the interpretation of thyroid function test results. OBJECTIVE We described the use of several commonly available laboratory-based approaches to investigate an isolated TSH elevation [232 mIU/liter; free T(4), 10 pmol/liter (reference interval, 10.0-23.0 pmol/liter), Vitros platform] in a clinically euthyroid elderly gentleman, which led to the diagnosis of macro-TSH. METHODS AND RESULTS TSH concentration of the patient was significantly lower (122 mIU/liter) when measured on the Advia Centaur platform. Serial dilution of the patient's sample showed a nonlinear increase in TSH recovery at increasing dilution (nonlinearity). Polyethylene glycol precipitation and mixing the patient's sample with a hypothyroid patient sample showed reduced TSH recovery, suggesting the presence of a high molecular weight interfering substance and excess TSH binding capacity, respectively. Heterophile blocking tube studies and rheumatoid factors were negative. Gel filtration chromatography demonstrated a TSH peak fraction that approximated the molecular size of IgG; together with the excess TSH binding capacity, this indicated the presence of TSH-IgG macro-TSH. A review of 12 macro-TSH case reports showed that samples with macro-TSH produce over-recovery with dilution, return negative results on anti-animal and anti-heterophile blocking studies, and commonly have recovery of less than 20% when subjected to polyethylene glycol precipitation. CONCLUSION Macro-TSH is an underrecognized laboratory interference. Routine laboratory techniques described above can help diagnose this rare entity. A close dialogue between the physician and the laboratory is important in approaching such cases.
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Affiliation(s)
- Tze Ping Loh
- Department of Laboratory Medicine, National University Hospital, Singapore.
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88
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Henderson MPA, Pond GR, Kavsak PA. Statistical and analytical approaches for assessing biomarkers: new approaches, new technologies, with the same-old rigor for evaluation. Clin Biochem 2012; 45:187-8. [PMID: 22300592 DOI: 10.1016/j.clinbiochem.2012.01.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 09/10/2011] [Accepted: 09/14/2011] [Indexed: 11/19/2022]
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89
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The coming of age of liquid chromatography coupled to tandem mass spectrometry in the endocrinology laboratory. J Chromatogr B Analyt Technol Biomed Life Sci 2012; 883-884:50-8. [DOI: 10.1016/j.jchromb.2011.08.027] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 08/19/2011] [Indexed: 02/07/2023]
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90
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Kunisue T, Eguchi A, Iwata H, Tanabe S, Kannan K. Analysis of thyroid hormones in serum of Baikal seals and humans by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunoassay methods: application of the LC-MS/MS method to wildlife tissues. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:10140-10147. [PMID: 22035339 DOI: 10.1021/es203002a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Thyroid hormones (THs) are essential for the regulation of growth and development in both humans and wildlife. Until recently, TH concentrations in the tissues of animals have been examined by immunoassay (IA) methods. IA methods are sensitive, but for TH analysis, they are compromised by a lack of adequate specificity. In this study, we determined the concentrations of six THs, L-thyroxine (T(4)), 3,3',5-triiodo-L-thyronine (T(3)), 3,3',5'-triiodo-L-thyronine (rT(3)), 3,5-diiodo-L-thyronine (3,5-T(2)), 3,3'-diiodo-L-thyronine (3,3'-T(2)), and 3-iodo-L-thyronine (3-T(1)), in the serum of humans (n = 79) and wild Baikal seals (n = 37), by isotope ([(13)C(6)]-T(4))-dilution liquid chromatography (LC)-tandem mass spectrometry (MS/MS), and compared the TH levels with those measured by an electrochemiluminescent immunoassay (ECLIA) method. T(3) and T(4) were detected in all serum samples of both humans and Baikal seals, whereas T(1), 3,3'-T(2), and 3,5-T(2) were below the limit of detection (LOD). rT(3) was detected in Baikal seal sera at concentrations higher than T(3) in 28 seal samples, indicating an anomaly in deiodinase activity in Baikal seals. In humans, regression analyses of TH concentrations, measured by ECLIA and LC-MS/MS methods, showed significant correlations for T(4) (r = 0.852) and T(3) (r = 0.676; after removal of a serum sample with abnormal T(3) levels). In Baikal seals, a low correlation coefficient (r = 0.466) for T(4) levels and no correlation for T(3) levels (p = 0.093) were found between ECLIA and LC-MS/MS methods. These results suggest that interference by a nonspecific reaction against anti-T(3) and anti-T(4) antibodies used in the ECLIA can contribute to inaccuracies in TH measurement in Baikal seals. When the relationship between concentrations of THs in sera and dioxin-like toxic equivalents in blubber samples of Baikal seals (n = 19) was examined, a significantly negative correlation was found for serum T(4) levels measured by the LC-MS/MS method, but not for those measured by ECLIA. Thus, our results indicate that the LC-MS/MS method is more reliable and accurate for the elucidation of alteration in circulating TH levels in wildlife, as caused by environmental and physiological factors.
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Affiliation(s)
- Tatsuya Kunisue
- Wadsworth Center, New York State Department of Health, and Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, New York 12201-0509, United States.
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91
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Grant RP. High Throughput Automated LC-MS/MS Analysis of Endogenous Small Molecule Biomarkers. Clin Lab Med 2011; 31:429-41. [DOI: 10.1016/j.cll.2011.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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92
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Kunisue T, Fisher JW, Kannan K. Modulation of thyroid hormone concentrations in serum of rats coadministered with perchlorate and iodide-deficient diet. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2011; 61:151-158. [PMID: 21573761 DOI: 10.1007/s00244-011-9677-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/18/2011] [Indexed: 05/30/2023]
Abstract
Perchlorate can perturb thyroid hormone (TH) homeostasis by competitive inhibition of iodide uptake by the thyroid gland. Until recently, the effects of perchlorate on TH homeostasis were examined by measuring serum concentrations of THs by immunoassay (IA) methods. IA methods are sensitive, but for TH analysis they are compromised by lack of adequate specificity. In this study, we determined the concentrations of six THs: L-thyroxine (T₄), 3,3',5-triiodo-L-thyronine (T₃), 3,3',5'-triiodo-L-thyronine (rT₃), 3,5-diiodo-L-thyronine, 3,3'-diiodo-L-thyronine, and 3-iodo-L-thyronine in the serum of rats administered perchlorate by isotope (¹³C₆-T₄)-dilution liquid chromatography-tandem mass spectrometry. The method recoveries for THs spiked into a serum matrix were between 97.0% and 115%, with a coefficient of variation of 2.1% to 9.4%. Rats were placed on an iodide-deficient or iodide-sufficient diet for 2.5 months, and for the last 2 weeks of that period they were provided drinking water either without or with perchlorate (10 mg/kg body weight/day). No significant differences in serum concentrations of T₃ and T₄ were observed between rats given iodide-deficient and iodide-sufficient diets for 2 or 2.5 months. After 24 h of perchlorate exposure, significantly lower concentrations of T₃ and T₄ were found in the serum of rats administered the iodide-deficient diet but not in rats administered the iodide-sufficient diet. However, after 2 weeks of perchlorate exposure, TH levels in rats fed the iodide-sufficient diet were also significantly lower than those in control rats. Our results suggest that perchlorate affects TH homeostasis and that such effects are more pronounced under iodide-deficient nutrition.
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Affiliation(s)
- Tatsuya Kunisue
- Wadsworth Center, New York State Department of Health, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, USA
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93
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Moleti M, Trimarchi F, Vermiglio F. Doubts and Concerns about Isolated Maternal Hypothyroxinemia. J Thyroid Res 2011; 2011:463029. [PMID: 21765991 PMCID: PMC3134327 DOI: 10.4061/2011/463029] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 04/10/2011] [Indexed: 12/02/2022] Open
Abstract
There is evidence that isolated maternal hypothyroxinemia may have detrimental effects on both mother and foetus. Nonetheless, this condition is still far from being universally accepted as a separate thyroid disease, and a standard definition of this state of mild thyroid underfunction is still lacking. We will review the biochemical criteria used to define isolated maternal hypothyroxinemia, together with current methodological issues related to FT4 assays. We will also discuss its epidemiological impact in both iodine-deficient and-sufficient areas, and the effectiveness of iodine prophylaxis on maternal thyroid function and neuropsychomotor development in offspring.
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Affiliation(s)
- Mariacarla Moleti
- Sezione di Endocrinologia, Dipartimento Clinico Sperimentale di Medicina e Farmacologia, Università de Messina, 98125 Messina, Italy
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94
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Higashi T, Ichikawa T, Shimizu C, Nagai S, Inagaki S, Min JZ, Chiba H, Ikegawa S, Toyo’oka T. Stable isotope-dilution liquid chromatography/tandem mass spectrometry method for determination of thyroxine in saliva. J Chromatogr B Analyt Technol Biomed Life Sci 2011; 879:1013-7. [DOI: 10.1016/j.jchromb.2011.02.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Revised: 02/23/2011] [Accepted: 02/28/2011] [Indexed: 10/18/2022]
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95
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Longitudinal comparison of thyroxine pharmacokinetics between pregnant and nonpregnant women: a stable isotope study. Ther Drug Monit 2011; 32:767-73. [PMID: 20962709 DOI: 10.1097/ftd.0b013e3181f12fe5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The treatment of maternal hypothyroidism presents clinicians with a unique challenge, because dosing regimens previously developed and validated for nonpregnant women cannot be easily extrapolated to dosing in pregnancy. Thyroid hormone requirement increases by 20% to 40% early during pregnancy, persisting throughout gestation. Accordingly, women with treated hypothyroidism need to increase their levothyroxine dose to prevent maternal hypothyroidism and the associated impaired cognitive development and increased fetal mortality. We investigated the pharmacokinetic properties of levothyroxine during pregnancy through the use of a novel, traceable form of levothyroxine. The objective was to conduct a longitudinal study to determine whether levothyroxine pharmacokinetics differ in the pregnant versus nonpregnant state. We used a unique C-levothyroxine-tracer method to distinguish between endogenous and exogenous levothyroxine and studied the pharmacokinetics of a single oral dose of levothyroxine using tandem mass spectrometry. Moreover, we were able to detect single dose amounts of the drug, in picogram/mL concentrations. The area under the curve was 23.0 ng*h/mL in pregnancy and 14.8 ng*h/mL in nonpregnant women (P < 0.03) with median serum half-lives of 32.1 hours and 24.1 hours, respectively (P < 0.04). Further research involves the measurement of free thyroxine on these samples using tandem mass spectrometry. Future work should focus on the mechanisms responsible for the gestational differences in pharmacokinetics and whether these should necessitate dose schedule changes in pregnancy.
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96
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Midgley JE. “All that glisters is not gold”: Ultrafiltration and free thyroxine measurement. Clin Biochem 2011; 44:151-3. [DOI: 10.1016/j.clinbiochem.2010.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/14/2010] [Accepted: 11/03/2010] [Indexed: 10/18/2022]
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