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Abstract
Thyroid hormones are primarily responsible for regulating the basal metabolic rate but also make important contributions to reproductive function and fetal development. Both hyper- and hypothyroidism in pregnancy have been associated with increased risks of complications that include preeclampsia and low birth weight, among others. Furthermore, thyroid hormone deficiency in the developing fetus results in neurodevelopmental delay. As the fetus is exclusively reliant on maternal thyroid hormone for most of the first trimester and requires continued maternal supply until birth, identifying maternal thyroid dysfunction is critically important. However, evaluating thyroid function in pregnancy is challenging because of the many physiological changes that affect concentrations of thyroid-related analytes. Increasing plasma human chorionic gonadotropin (hCG) concentrations in the second half of the first trimester elicit a corresponding transient decrease in thyroid-stimulating hormone (TSH), and continually increasing estradiol concentrations throughout pregnancy cause substantial increases in thyroxine-binding globulin (TBG) and total thyroxine (T4) relative to the nonpregnant state. Lastly, free T4 concentrations gradually decrease with increasing gestational age. For these reasons, it is essential to interpret thyroid function test results in the context of trimester-specific reference intervals to avoid misclassification of thyroid status. This review summarizes the effects of thyroid dysfunction prior to conception and during pregnancy and describes considerations for the laboratory assessment of thyroid function in pregnant women.
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Affiliation(s)
- K Aaron Geno
- Department of Pathology, Texas Tech University Health Sciences Center, El Paso, TX, USA
| | - Robert D Nerenz
- Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.,Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
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Ilias I, Milionis C, Koukkou E. Further understanding of thyroid function in pregnant women. Expert Rev Endocrinol Metab 2022; 17:365-374. [PMID: 35831988 DOI: 10.1080/17446651.2022.2099372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 07/05/2022] [Indexed: 10/17/2022]
Abstract
INTRODUCTION Normal thyroid status throughout pregnancy is important for both maternal and fetal health. Despite the bulk of contemporary research honing on thyroid function in gestation and the relevant disorders, there are still gaps in our current knowledge about the etiology and treatment of thyroid diseases in pregnant women. AREAS COVERED This article analyzes the adaptation of the thyroid gland to gestational physiological changes and attempts to explain the effect of several factors on thyroid function in pregnancy. It also stresses proper utilization and interpretation of thyroid tests during pregnancy and underlines the significance of proper screening and treatment of pregnant women aiming at favorable health outcomes. EXPERT OPINION Appropriate strategies for diagnosing and treating thyroid disease in pregnancy are important. Laboratory thyroid testing plays a leading role, but test results should be interpreted with caution. Given the possible serious maternal and fetal/neonatal complications of thyroid disease in pregnancy, we recommend universal screening with TSH measurements of all pregnant women. Additional assessment with determination of the levels of free thyroid hormones and thyroid antibodies may be necessary under certain conditions. The economic burden of such interventions should be considered.
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Affiliation(s)
- Ioannis Ilias
- Department of Endocrinology, Diabetes and Metabolism, Elena Venizelou Hospital, Athens, Greece
| | - Charalampos Milionis
- Department of Endocrinology, Diabetes and Metabolism, Elena Venizelou Hospital, Athens, Greece
| | - Eftychia Koukkou
- Department of Endocrinology, Diabetes and Metabolism, Elena Venizelou Hospital, Athens, Greece
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Lee SY, Pearce EN. Assessment and treatment of thyroid disorders in pregnancy and the postpartum period. Nat Rev Endocrinol 2022; 18:158-171. [PMID: 34983968 PMCID: PMC9020832 DOI: 10.1038/s41574-021-00604-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/19/2021] [Indexed: 12/13/2022]
Abstract
Thyroid disorders are prevalent in pregnant women. Furthermore, thyroid hormone has a critical role in fetal development and thyroid dysfunction can adversely affect obstetric outcomes. Thus, the appropriate management of hyperthyroidism, most commonly caused by Graves disease, and hypothyroidism, which in iodine sufficient regions is most commonly caused by Hashimoto thyroiditis, in pregnancy is important for the health of both pregnant women and their offspring. Gestational transient thyrotoxicosis can also occur during pregnancy and should be differentiated from Graves disease. Effects of thyroid autoimmunity and subclinical hypothyroidism in pregnancy remain controversial. Iodine deficiency is the leading cause of hypothyroidism worldwide. Despite global efforts to eradicate iodine deficiency disorders, pregnant women remain at risk of iodine deficiency due to increased iodine requirements during gestation. The incidence of thyroid cancer is increasing worldwide, including in young adults. As such, the diagnosis of thyroid nodules or thyroid cancer during pregnancy is becoming more frequent. The evaluation and management of thyroid nodules and thyroid cancer in pregnancy pose a particular challenge. Postpartum thyroiditis can occur up to 1 year after delivery and must be differentiated from other forms of thyroid dysfunction, as treatment differs. This Review provides current evidence and recommendations for the evaluation and management of thyroid disorders in pregnancy and in the postpartum period.
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Affiliation(s)
- Sun Y Lee
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, MA, USA
| | - Elizabeth N Pearce
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, MA, USA.
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Guo Y, Wei B, Dai W, Xie H. Establishment of trimester-specific reference intervals for thyroid stimulating hormone and free thyroxine during pregnancy in southwest China by indirect method. Ann Clin Biochem 2021; 59:234-241. [PMID: 34951326 DOI: 10.1177/00045632211063142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE A series of physiological changes in thyroid function occur during pregnancy and differ from those non-pregnant women. This study aimed to establish the pregnancy-specific reference intervals of TSH and FT4 using an indirect method based on the healthy pregnant women from southwest China population. METHODS Thyroid function test results which available on the Laboratory Information System (LIS) were collected from the pregnancies who visited the Obstetric Clinic or the Department of Gynecology between 1 January 2015, and 30 December 2020. We grouped the data by trimesters to establish the reference intervals (RIs) based on the clinical consensus of different levels of TSH and FT4 at different weeks of gestation. All arrangements were referenced to the document CLSI EP28-A3C. RESULTS A total of 33,040 thyroid function test results of pregnant women, aged 31 (28,33) years were statistical analyzed. Estimated RIs for TSH and FT4 in the first, second and third trimesters corresponding to the 2.5th and 97.5th percentiles in TPOAb negative were 0.02-5.23, 0.03-5.24, 0.37-5.68 mIU/L, 11.66-20.69, 10.1-18.59, 9.85-16.86pmol/L, respectively. CONCLUSION This study provides trimester-specific RIs for TSH and FT4 among healthy pregnant women in southwest China which guides clinicians to diagnosis and screen for thyroid disorders in this region.
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Affiliation(s)
- Ying Guo
- Department of Laboratory Medicine, West China Second Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, 12530Sichuan University, Chengdu, China
| | - Bin Wei
- Department of Laboratory Medicine/Clinical Research Center of Laboratory Medicine, West China Hospital, 12530Sichuan University, Chengdu, China
| | - Wei Dai
- Department of Laboratory Medicine, West China Second Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, 12530Sichuan University, Chengdu, China
| | - Hongjian Xie
- Department of Laboratory Medicine, West China Second Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, 12530Sichuan University, Chengdu, China
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Bunch DR, Firmender K, Harb R, El-Khoury JM. First- and Second-Trimester Reference Intervals for Thyroid Function Testing in a US Population. Am J Clin Pathol 2021; 155:776-780. [PMID: 33210132 DOI: 10.1093/ajcp/aqaa165] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
OBJECTIVES Thyroid dysfunction in pregnancy is associated with increased risk of adverse outcomes to mother and child. Trimester-specific reference intervals for thyroid function tests are not routinely provided by clinical laboratories. In this study, we present first- and second-trimester-specific reference intervals in a US population for thyroid-stimulating hormone (TSH), free thyroxine (FT4), total thyroxine (T4), and total triiodothyronine (T3) measured on Roche analyzers. METHODS We used patient samples from first- and second-trimester prenatal screening. Samples were limited to singleton pregnancies and negative screening results for thyroid peroxidase and thyroglobulin antibodies. Analytes (TSH, FT4, T4, and T3) were measured on a Roche Modular e170 then verified on a Roche cobas e801. RESULTS The reference intervals established on the e170 and verified on the e801 for the first trimester were 0.16 to 2.82 mIU/L for TSH, 12.0 to 18.5 pmol/L for FT4, 62.8 to 177.9 nmol/L for T4, and 1.5 to 3.4 nmol/L for T3. The reference intervals for the second trimester were 0.40 to 3.62 mIU/L for TSH, 10.2 to 16.6 pmol/L for FT4, 66.6 to 176.0 nmol/L for T4, and 1.56 to 3.6 nmol/L for T3. CONCLUSIONS This is the first report of trimester-specific reference intervals for thyroid function tests on Roche analyzers in the United States, and it is consistent with worldwide reports.
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Affiliation(s)
- Dustin R Bunch
- Department of Laboratory Medicine, Yale-New Haven Hospital, New Haven, CT.,Yale School of Medicine, Yale University, New Haven, CT
| | - Kyle Firmender
- Department of Laboratory Medicine, Yale-New Haven Hospital, New Haven, CT
| | - Roa Harb
- Department of Laboratory Medicine, Yale-New Haven Hospital, New Haven, CT.,Yale School of Medicine, Yale University, New Haven, CT
| | - Joe M El-Khoury
- Department of Laboratory Medicine, Yale-New Haven Hospital, New Haven, CT.,Yale School of Medicine, Yale University, New Haven, CT
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Geno KA, Reed MS, Cervinski MA, Nerenz RD. Evaluation of Thyroid Function in Pregnant Women Using Automated Immunoassays. Clin Chem 2021; 67:772-780. [PMID: 33928365 DOI: 10.1093/clinchem/hvab009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 12/21/2020] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Automated free thyroxine (FT4) immunoassays are widely available, but professional guidelines discourage their use in pregnant women due to theoretical under-recoveries attributed to increased thyroid hormone binding capacity and instead advocate the use of total T4 (TT4) or free thyroxine index (FTI). The impact of this recommendation on the classification of thyroid status in apparently euthyroid pregnant patients was evaluated. METHODS After excluding specimens with thyroid autoantibody concentrations above reference limits, thyroid-stimulating hormone (TSH), FT4, TT4, and T-uptake were measured on the Roche Cobas® platform in remnant clinical specimens from at least 147 nonpregnant women of childbearing age and pregnant women at each trimester. Split-sample comparisons of FT4 as measured by the Cobas and equilibrium dialysis were performed. RESULTS FT4 decreased with advancing gestational age by both immunoassay and equilibrium dialysis. TSH declined during the first trimester, remained constant in the second, and increased throughout the third, peaking just before delivery. Interpretation of TT4 concentrations using 1.5-times the nonpregnant reference interval classified 13.6% of first trimester specimens below the lower reference limit despite TSH concentrations within trimester-specific reference intervals. Five FTI results from 480 pregnant individuals (about 1.0%) fell outside the manufacturer's reference interval. CONCLUSIONS Indirect FT4 immunoassay results interpreted in the context of trimester-specific reference intervals provide a practical and viable alternative to TT4 or FTI. Declining FT4 and increasing TSH concentrations near term suggest that declining FT4 is not an analytical artifact but represents a true physiological change in preparation for labor and delivery.
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Affiliation(s)
- K Aaron Geno
- Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Health System, Lebanon, NH, USA.,Geisel School of Medicine at Dartmouth, Hanover, NH, USA.,Department of Pathology, Texas Tech University Health Sciences Center El Paso, El Paso, TX, USA
| | - Matthew S Reed
- Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Health System, Lebanon, NH, USA.,Southern New Hampshire University, Manchester, NH, USA
| | - Mark A Cervinski
- Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Health System, Lebanon, NH, USA.,Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Robert D Nerenz
- Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Health System, Lebanon, NH, USA.,Geisel School of Medicine at Dartmouth, Hanover, NH, USA
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Xiao C, Grandjean P, Valvi D, Nielsen F, Jensen TK, Weihe P, Oulhote Y. Associations of Exposure to Perfluoroalkyl Substances With Thyroid Hormone Concentrations and Birth Size. J Clin Endocrinol Metab 2020; 105:dgz147. [PMID: 31665456 PMCID: PMC7112969 DOI: 10.1210/clinem/dgz147] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/25/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Adequate thyroid function during pregnancy is essential for optimal fetal growth. Gestational exposure to perfluoroalkyl substances (PFAS) can negatively affect birth size and disrupt maternal and neonatal thyroid function, although the interrelationship is unclear. OBJECTIVE We aimed to quantify the associations between maternal serum-PFAS concentrations and birth weight, birth length, and cranial circumference. We also aimed to estimate associations between PFAS and thyroid hormone (TH) concentrations, thereby elucidating whether THs potentially mediate the associations between PFAS concentrations and birth size. METHODS We studied a population-based prospective cohort of 172 mother-singleton pairs from the Faroe Islands. Twelve PFAS were measured in maternal serum obtained at 34 weeks of gestation. THs were measured in maternal and cord serum. Associations between PFAS concentrations and birth size and TH concentrations were estimated using multivariable linear regressions. Sex-stratified analyses along with a mediation analysis were performed to estimate potential mediating effects of THs in the association between PFAS and birth outcomes. RESULTS Several PFASs were negatively associated with birth weight, length, and head circumference, and a general positive association between maternal serum-PFASs and cord serum-thyroid-stimulating hormone (TSH; also known as thyrotropin) was found. For instance, a doubling in perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was associated with a 53% (95% CI, 18%-99%) and 40% (95% CI, 8%-81%) increases in TSH concentrations, respectively. There was little evidence of sexually dimorphic associations. Overall, THs were not found to mediate associations between PFASs and birth size. CONCLUSION In this study, several PFASs were negatively associated with birth size and increased THs; however, this did not explain lower birth weight among children exposed to PFAS.
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Affiliation(s)
- Christina Xiao
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
- EHESP-School of Public Health, Sorbonne Paris Cité, Rennes, France
| | - Philippe Grandjean
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
- Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark
| | - Damaskini Valvi
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Flemming Nielsen
- Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark
| | - Tina Kold Jensen
- Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark
| | - Pal Weihe
- The Faroese Hospital System, Tórshavn, Faroe Islands
| | - Youssef Oulhote
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts at Amherst, Massachusetts
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Gronowski AM, Yarbrough ML. The Women's Health Diagnostic Gap. Endocrinology 2018; 159:776-778. [PMID: 29325073 DOI: 10.1210/en.2017-03178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 12/05/2017] [Indexed: 11/19/2022]
Abstract
Pregnancy remains a significant health risk to women in both developed and underdeveloped countries. Worldwide, 10 to 20 million women have pregnancy complications including ectopic pregnancy, preterm birth, gestational diabetes mellitus, and hypertensive states, including preeclampsia. Despite advancements in women's health research, there is a large gap in the diagnostic tools available to screen, diagnose, and monitor these conditions. Herein, we examine existing diagnostic tools, such as the human chorionic gonadotropin discriminatory zone, cervicovaginal fetal fibronectin, sFlt-1:PlGF ratio, and glucose tolerance testing. We suggest specific objectives to improve diagnostic testing during pregnancy, including (1) developing high-quality biospecimen banks; (2) educating professionals on performance characteristics of screening tests for low prevalence diseases; (3) funding studies that address diseases unique to pregnancy; and (4) establishing trimester-specific reference intervals. Meeting these objectives could begin to narrow the diagnostic gap in women's health.
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Affiliation(s)
- Ann M Gronowski
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri
| | - Melanie L Yarbrough
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri
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