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Gmür S, Konrad D, Fingerhut R. Prevalence of Transient Hypothyroidism in Children Diagnosed with Congenital Hypothyroidism between 2000 and 2016. Int J Mol Sci 2023; 24:ijms24032817. [PMID: 36769132 PMCID: PMC9917150 DOI: 10.3390/ijms24032817] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/16/2023] [Accepted: 01/29/2023] [Indexed: 02/05/2023] Open
Abstract
Newborn screening (NBS) for congenital hypothyroidism (CH) was introduced in Switzerland in 1977, which allowed for the preclinical, biochemical diagnosis. The aim of this study was to evaluate the prevalence of transient CH (tCH) in the canton of Zurich. In this analytical cohort study, all newborns born in the canton of Zurich, between the 1st of January 2000 and the 30st of June 2016, with a TSH value above 15 mU/L (whole blood) were included. There were 115 cases out of 247,918 babies born during the study period. However, 23 cases had to be excluded due to missing data. The definite diagnosis was made after a thyroxine withdrawal at 2 years of age. The total prevalence of confirmed CH and the female to male ratio (f/m) were 1:2695 and 2.17:1; for permanent CH (pCH), 1:3443 and 2.8:1; and for tCH, 1:12,396 and 1:1, respectively. The TSH value was significantly higher in pCH compared to tCH, at 130.3 (62.9-171.9) and 36.4 (26.5-53.3) (median and interquartile range), respectively (p < 0.001). The prevalences found for congenital hypothyroidism and its transient form are comparable to previous studies. TSH concentration at birth was predictive for the further course of the disease. Low birth weight correlated with a tCH, whereas low gestational age did not. The dominance of the female sex in congenital hypothyroidism is supported by a gender ratio of 2.17:1.
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Affiliation(s)
- Sabrina Gmür
- Department of Endocrinology & Diabetology, University Children’s Hospital Zurich, University of Zurich, CH-8032 Zurich, Switzerland
| | - Daniel Konrad
- Department of Endocrinology & Diabetology, University Children’s Hospital Zurich, University of Zurich, CH-8032 Zurich, Switzerland
- Children’s Research Center, University Children’s Hospital Zurich, University of Zurich, CH-8032 Zurich, Switzerland
| | - Ralph Fingerhut
- Children’s Research Center, University Children’s Hospital Zurich, University of Zurich, CH-8032 Zurich, Switzerland
- Swiss Newborn Screening Laboratory, University Children’s Hospital, CH-8032 Zurich, Switzerland
- Correspondence: ; Tel.: +49-961-309-327
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Prencipe N, Marinelli L, Varaldo E, Cuboni D, Berton AM, Bioletto F, Bona C, Gasco V, Grottoli S. Isolated anterior pituitary dysfunction in adulthood. Front Endocrinol (Lausanne) 2023; 14:1100007. [PMID: 36967769 PMCID: PMC10032221 DOI: 10.3389/fendo.2023.1100007] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/21/2023] [Indexed: 03/29/2023] Open
Abstract
Hypopituitarism is defined as a complete or partial deficiency in one or more pituitary hormones. Anterior hypopituitarism includes secondary adrenal insufficiency, central hypothyroidism, hypogonadotropic hypogonadism, growth hormone deficiency and prolactin deficiency. Patients with hypopituitarism suffer from an increased disability and sick days, resulting in lower health status, higher cost of care and an increased mortality. In particular during adulthood, isolated pituitary deficits are not an uncommon finding; their clinical picture is represented by vague symptoms and unclear signs, which can be difficult to properly diagnose. This often becomes a challenge for the physician. Aim of this narrative review is to analyse, for each anterior pituitary deficit, the main related etiologies, the characteristic signs and symptoms, how to properly diagnose them (suggesting an easy and reproducible step-based approach), and eventually the treatment. In adulthood, the vast majority of isolated pituitary deficits are due to pituitary tumours, head trauma, pituitary surgery and brain radiotherapy. Immune-related dysfunctions represent a growing cause of isolated pituitary deficiencies, above all secondary to use of oncological drugs such as immune checkpoint inhibitors. The diagnosis of isolated pituitary deficiencies should be based on baseline hormonal assessments and/or dynamic tests. Establishing a proper diagnosis can be quite challenging: in fact, even if the diagnostic methods are becoming increasingly refined, a considerable proportion of isolated pituitary deficits still remains without a certain cause. While isolated ACTH and TSH deficiencies always require a prompt replacement treatment, gonadal replacement therapy requires a benefit-risk evaluation based on the presence of comorbidities, age and gender of the patient; finally, the need of growth hormone replacement therapies is still a matter of debate. On the other side, prolactin replacement therapy is still not available. In conclusion, our purpose is to offer a broad evaluation from causes to therapies of isolated anterior pituitary deficits in adulthood. This review will also include the evaluation of uncommon symptoms and main etiologies, the elements of suspicion of a genetic cause and protocols for diagnosis, follow-up and treatment.
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Can Mild-to-Moderate Iodine Deficiency during Pregnancy Alter Thyroid Function? Lessons from a Mother-Newborn Cohort. Nutrients 2022; 14:nu14245336. [PMID: 36558495 PMCID: PMC9781516 DOI: 10.3390/nu14245336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/08/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
Severe iodine deficiency during pregnancy has substantial hormonal consequences, such as fetal brain damage. Data on the potential effects of mild-to-moderate iodine deficiency on the thyroid function of pregnant women and their newborns are scarce and divergent. We investigated the association between iodine intake in pregnancy and maternal and neonatal thyroid function in a region with mild-to-moderate iodine deficiency. Pregnant women’s iodine status was evaluated using an iodine food frequency questionnaire, serum thyroglobulin (Tg), and urinary iodine concentration (UIC). Neonatal thyrotropin (nTSH) values were measured after birth. Obstetrics and anthropometric data were also collected. Among the 178 women (median age 31 years) included in the study, median (interquartile range) estimated dietary iodine intake, Tg and UIC were 179 (94−268) μg/day, 18 (11−33) μg/L, and 60 (41−95) μg/L, respectively. There was a significant inverse association of iodine intake with Tg values among the study population (β = −0.2, F = 7.5, p < 0.01). Women with high free triiodothyronine (FT3) values were more likely to exhibit an estimated iodine intake below the estimated average requirement (160 μg/day, odds ratio [OR] = 2.6; 95% confidence interval [CI], 1.1−6.4; p = 0.04) and less likely to consume iodine-containing supplements (OR = 0.3, 95% CI, 0.1−0.8; p = 0.01). It is possible that thyroid function may be affected by iodine insufficiency during pregnancy in regions with mild-to-moderate iodine deficiency. The relatively small sample size of the studied population warrants further investigation.
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Sasidharan Pillai S, Quintos JB. Thyroid function tests of iodine deficiency goiter can mimic thyroid hormone resistance alpha. J Pediatr Endocrinol Metab 2022; 35:1433-1436. [PMID: 36100365 DOI: 10.1515/jpem-2022-0345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/29/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Iodine deficiency goiter can develop in children on a restrictive diet and most have normal thyroid function. We report a 6-year-old girl with iodine deficiency goiter with thyroid function studies mimicking thyroid hormone resistance alpha. Thyroid hormones mediate its effects through thyroid hormone receptors alpha and beta. Biochemical picture of low/low-normal T4 and high/high-normal T3 levels, variably reduced reverse T3 and normal TSH is characteristic of thyroid hormone resistance alpha. CASE PRESENTATION A 6-year-old girl, born out of non-consanguineous marriage presented with goiter of 1.5 years duration. She was without symptoms of thyroid dysfunction. The patient was evaluated at one year of age for macrocephaly with cranial ultrasound which was normal. She had normal growth and development. Patient was vegan and was not on any medications or supplements. Laboratory work up showed TSH 5.03 uIU/mL (0.34-5.5), FT4 0.3 ng/dL (0.58-1.2), FT3 5.3 pg/mL (2.5-3.9), total T3 258 ng/dL (94-241), reverse T3 <5.0 ng/dL (8.3-22.9) and negative thyroglobulin antibody and thyroid peroxidase antibody. Thyroglobulin level was 1,098.8 ng/mL (<13 ug/L), and urine iodine 15.8 ug/L (<100 ug/L) confirming a diagnosis of iodine deficiency goiter. Patient was started on iodine supplements, 150 ug daily and repeat work up 3 months later were TSH: 2.717 uIU/mL, T3, total 182 ng/dL, T4, total 9.3 ug/dL, FT 4 2.1 ng/dL. CONCLUSIONS Iodine deficiency goiter may present with low FT 4, elevated T3 and normal TSH mimicking thyroid hormone resistance alpha and should be considered in children on restrictive diet.
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Affiliation(s)
- Sabitha Sasidharan Pillai
- Division of Pediatric Endocrinology, Hasbro Children's Hospital, Providence, USA.,Department of Pediatrics, The Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Jose Bernardo Quintos
- Division of Pediatric Endocrinology, Hasbro Children's Hospital, Providence, USA.,Department of Pediatrics, The Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
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Hoermann R, Pekker MJ, Midgley JEM, Larisch R, Dietrich JW. Principles of Endocrine Regulation: Reconciling Tensions Between Robustness in Performance and Adaptation to Change. Front Endocrinol (Lausanne) 2022; 13:825107. [PMID: 35757421 PMCID: PMC9219553 DOI: 10.3389/fendo.2022.825107] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 05/02/2022] [Indexed: 02/06/2023] Open
Abstract
Endocrine regulation in the hypothalamic-pituitary-thyroid (HPT) axis is orchestrated by physiological circuits which integrate multiple internal and external influences. Essentially, it provides either of the two responses to overt biological challenges: to defend the homeostatic range of a target hormone or adapt it to changing environmental conditions. Under certain conditions, such flexibility may exceed the capability of a simple feedback control loop, rather requiring more intricate networks of communication between the system's components. A new minimal mathematical model, in the form of a parametrized nonlinear dynamical system, is here formulated as a proof-of-concept to elucidate the principles of the HPT axis regulation. In particular, it allows uncovering mechanisms for the homeostasis of the key biologically active hormone free triiodothyronine (FT3). One mechanism supports the preservation of FT3 homeostasis, whilst the other is responsible for the adaptation of the homeostatic state to a new level. Together these allow optimum resilience in stressful situations. Preservation of FT3 homeostasis, despite changes in FT4 and TSH levels, is found to be an achievable system goal by joining elements of top-down and bottom-up regulation in a cascade of targeted feedforward and feedback loops. Simultaneously, the model accounts for the combination of properties regarded as essential to endocrine regulation, namely sensitivity, the anticipation of an adverse event, robustness, and adaptation. The model therefore offers fundamental theoretical insights into the effective system control of the HPT axis.
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Affiliation(s)
- Rudolf Hoermann
- Department for Nuclear Medicine, Klinikum Lüdenscheid, Lüdenscheid, Germany
| | - Mark J. Pekker
- Mathematical Sciences Department, University of Alabama, Huntsville, AL, United States
| | | | - Rolf Larisch
- Department for Nuclear Medicine, Klinikum Lüdenscheid, Lüdenscheid, Germany
| | - Johannes W. Dietrich
- Diabetes, Endocrinology and Metabolism Section, Department of Medicine I, St. Josef Hospital, Ruhr-University of Bochum, Bochum, Germany
- Diabetes Centre Bochum/Hattingen, Ruhr University of Bochum, Bochum, Germany
- Ruhr Center for Rare Diseases (CeSER), Ruhr University of Bochum and Witten/Herdecke University, Bochum, Germany
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Gustin K, Vahter M, Barman M, Jacobsson B, Skröder H, Filipsson Nyström H, Sandin A, Sandberg AS, Wold AE, Kippler M. Assessment of Joint Impact of Iodine, Selenium, and Zinc Status on Women's Third-Trimester Plasma Thyroid Hormone Concentrations. J Nutr 2022; 152:1737-1746. [PMID: 35383840 PMCID: PMC9258587 DOI: 10.1093/jn/nxac081] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/02/2022] [Accepted: 03/31/2022] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Iodine is essential for synthesizing thyroid hormones, but other micronutrients are also required for optimal thyroid function. However, there is a lack of data on combined micronutrient status in relation to thyroid hormones in pregnancy. OBJECTIVES We aimed to assess the joint associations of iodine, selenium, and zinc status with plasma concentrations of thyroid hormones and thyroid-stimulating hormone (TSH) in pregnancy. METHODS We included 531 pregnant women (aged 22-40 y) participating in a Swedish birth cohort who provided blood and spot urine samples in gestational weeks 27-33 (mean: 29). Associations of urinary iodine concentration (UIC), plasma selenium concentration, and plasma zinc concentration (measured by inductively coupled plasma mass spectrometry) with plasma hormone concentrations [total and free thyroxine (tT4, fT4), total and free triiodothyronine (tT3, fT3), and TSH] were explored with Bayesian kernel machine regression (BKMR; n = 516; outliers excluded) and multivariable-adjusted linear regression (n = 531; splined for nonlinear associations). RESULTS Median (IQR) micronutrient concentrations were 112 μg/L (80-156 μg/L) for UIC, 67 μg/L (58-76 μg/L) for plasma selenium, and 973 μg/L (842-1127 μg/L) for plasma zinc; the former 2 median values were below recommended concentrations (150 μg/L and 70 μg/L, respectively). Mean ± SD TSH concentration was 1.7 ± 0.87 mIU/L, with 98% < 4 mIU/L. BKMR showed a positive trend of joint micronutrient concentrations in relation to TSH. Plasma zinc was most influential for all hormones but tT3, for which plasma selenium was most influential. In adjusted linear regression models, zinc was positively associated with tT4, tT3, and TSH, and <1200 μg/L also with fT4 and fT3. Selenium was inversely associated with fT3, and <85 μg/L with tT3. CONCLUSIONS Pregnant women's plasma TSH concentrations in the early third trimester increased with increasing joint status of iodine, selenium, and zinc. Zinc and selenium were more influential than iodine for the hormone concentrations. Multiple micronutrients need consideration in future studies of thyroid hormone status.
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Affiliation(s)
- Klara Gustin
- Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden
| | - Marie Vahter
- Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden
| | - Malin Barman
- Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden,Food and Nutrition Science, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Bo Jacobsson
- Department of Obstetrics and Gynecology, Institute of Clinical Science, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden,Department of Obstetrics and Gynecology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Helena Skröder
- Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden
| | - Helena Filipsson Nyström
- Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden,Department of Endocrinology, Specialized Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden,Wallenberg's Centre for Molecular and Translational Medicine, Sahlgrenska University Hopsital, Gothenburg, Sweden
| | - Anna Sandin
- Department of Clinical Science, Pediatrics, Sunderby Research Unit, Umeå University, Umeå, Sweden
| | - Ann-Sofie Sandberg
- Food and Nutrition Science, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Agnes E Wold
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Businge CB, Longo-Mbenza B, Kengne AP. Iodine deficiency in pregnancy along a concentration gradient is associated with increased severity of preeclampsia in rural Eastern Cape, South Africa. BMC Pregnancy Childbirth 2022; 22:98. [PMID: 35120491 PMCID: PMC8815178 DOI: 10.1186/s12884-021-04356-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 12/17/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Preeclampsia is a leading cause of maternal mortality and morbidity in South Africa. Iodine deficiency in pregnancy, which is amenable to correction through iodine supplementation, has been reported to increase the risk of preeclampsia. However, the association of iodine nutrition status with preeclampsia in South Africa has not been studied. METHODS We enrolled 51 randomly selected normotensive pregnant controls at term together with 51 consecutively selected cases of preeclampsia and 51 cases of severe preeclampsia/eclampsia, all in the third trimester, from Mthatha Regional and Nelson Mandela Academic Hospital in the Eastern Cape Province. Urinary iodine concentration (UIC), serum thyroid-stimulating hormone (TSH), triiodothyronine (FT3), thyroxine (FT4) and thyroglobulin (Tg) levels were compared between cases and controls. RESULTS The respective chronological and gestational ages at enrolment for normotensive, preeclampsia and severe preeclampsia/eclampsia participants were: age 23, 24 and 19 years (p = 0.001), and gestational age 38, 34, and 35 weeks (p < 0.001). The median gravidity was 1 for all three groups. The median UIC, FT4, FT3 revealed a decreasing and Tg a rising trend with the severity of preeclampsia (p < 0.05). TSH had a non-significant rising trend (p > 0.05). The respective median values for normotensive, preeclampsia and severe preeclampsia/eclampsia participants were UIC 217.1, 127.7, and 98.8 μg/L; FT4 14.2, 13.7, and 12. pmol/L; FT3 4.8, 4.4, and 4.0 pmol//L; Tg 19.4, 21.4, and 32. Nine microgram per liter; TSH 2.3, 2.3, and 2.5 mIU/L. UIC < 100 μg/L, Tg > 16 μg/L and FT4 < 11.3 pmol/L were independent predictors of preeclampsia/eclampsia syndrome. CONCLUSION Women with severe preeclampsia/eclampsia had significantly low UIC and high Tg, suggesting protracted inadequate iodine intake. Inadequate iodine intake during pregnancy severe enough to cause elevated Tg and FT4 deficiency was associated with an increased risk of severe preeclampsia/eclampsia.
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Affiliation(s)
- Charles Bitamazire Businge
- Department of Obstetrics and Gynaecology, Faculty of Health Sciences, Walter Sisulu University, Private Bag x1 WSU, Mthatha, 5117 South Africa
- Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Benjamin Longo-Mbenza
- Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
- LOMO University of Research, Kinshasa, Democratic Republic of Congo
| | - Andre Pascal Kengne
- Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Non-Communicable Disease Research Unit, South African Medical Research Council, Cape Town, South Africa
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Matsuyama M, Sawada H, Inoue S, Hishinuma A, Sekiya R, Sato Y, Moritake H. Goiter in a 6-year-old patient with novel thyroglobulin gene variant (Gly145Glu) causing intracellular thyroglobulin transport disorder: Correlation between goiter size and the free T3 to free T4 ratio. Clin Pediatr Endocrinol 2022; 31:185-191. [PMID: 35928386 PMCID: PMC9297170 DOI: 10.1297/cpe.2022-0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 04/12/2022] [Indexed: 11/04/2022] Open
Affiliation(s)
- Misayo Matsuyama
- Division of Pediatrics, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Hirotake Sawada
- Department of Fundamental Nursing, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Shinobu Inoue
- Division of Pediatrics, National Hospital Organization Miyazaki Higashi Hospital, Miyazaki, Japan
| | - Akira Hishinuma
- Department of Infection Control and Clinical Laboratory Medicine, Dokkyo Medical University, Mibu, Japan
| | - Ryo Sekiya
- Division of Surgery, Miyazaki Zenjinkai Hospital, Miyazaki, Japan
| | - Yuichiro Sato
- Departoment of Diagnostic Pathology, University of Miyazaki Hospital, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Hiroshi Moritake
- Division of Pediatrics, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
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Lossow K, Renko K, Schwarz M, Schomburg L, Schwerdtle T, Kipp AP. The Nutritional Supply of Iodine and Selenium Affects Thyroid Hormone Axis Related Endpoints in Mice. Nutrients 2021; 13:nu13113773. [PMID: 34836027 PMCID: PMC8625755 DOI: 10.3390/nu13113773] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/21/2021] [Accepted: 10/22/2021] [Indexed: 01/06/2023] Open
Abstract
Selenium and iodine are the two central trace elements for the homeostasis of thyroid hormones but additional trace elements such as iron, zinc, and copper are also involved. To compare the primary effects of inadequate intake of selenium and iodine on the thyroid gland, as well as the target organs of thyroid hormones such as liver and kidney, mice were subjected to an eight-week dietary intervention with low versus adequate selenium and iodine supply. Analysis of trace element levels in serum, liver, and kidney demonstrated a successful intervention. Markers of the selenium status were unaffected by the iodine supply. The thyroid gland was able to maintain serum thyroxine levels even under selenium-deficient conditions, despite reduced selenoprotein expression in liver and kidney, including deiodinase type 1. Thyroid hormone target genes responded to the altered selenium and iodine supply, whereas the iron, zinc, and copper homeostasis remained unaffected. There was a notable interaction between thyroid hormones and copper, which requires further clarification. Overall, the effects of an altered selenium and iodine supply were pronounced in thyroid hormone target tissues, but not in the thyroid gland.
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Affiliation(s)
- Kristina Lossow
- Department of Nutritional Physiology, Institute of Nutritional Sciences, Friedrich Schiller University Jena, 07743 Jena, Germany; (K.L.); (M.S.)
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, 07743 Jena, Germany; (L.S.); (T.S.)
- German Institute of Human Nutrition, 14558 Nuthetal, Germany
| | - Kostja Renko
- German Federal Institute for Risk Assessment (BfR), 12277 Berlin, Germany;
| | - Maria Schwarz
- Department of Nutritional Physiology, Institute of Nutritional Sciences, Friedrich Schiller University Jena, 07743 Jena, Germany; (K.L.); (M.S.)
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, 07743 Jena, Germany; (L.S.); (T.S.)
| | - Lutz Schomburg
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, 07743 Jena, Germany; (L.S.); (T.S.)
- Institute for Experimental Endocrinology, Charité-University Medical School Berlin, 13353 Berlin, Germany
| | - Tanja Schwerdtle
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, 07743 Jena, Germany; (L.S.); (T.S.)
- German Federal Institute for Risk Assessment (BfR), 12277 Berlin, Germany;
- Department of Food Chemistry, Institute of Nutritional Science, University of Potsdam, 14558 Nuthetal, Germany
| | - Anna Patricia Kipp
- Department of Nutritional Physiology, Institute of Nutritional Sciences, Friedrich Schiller University Jena, 07743 Jena, Germany; (K.L.); (M.S.)
- TraceAge-DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly, 07743 Jena, Germany; (L.S.); (T.S.)
- Correspondence:
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Næss S, Markhus MW, Strand TA, Kjellevold M, Dahl L, Stokland AEM, Nedrebø BG, Aakre I. Iodine Nutrition and Iodine Supplement Initiation in Association with Thyroid Function in Mildly-to-Moderately Iodine-Deficient Pregnant and Postpartum Women. J Nutr 2021; 151:3187-3196. [PMID: 34255063 PMCID: PMC8485914 DOI: 10.1093/jn/nxab224] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/18/2021] [Accepted: 06/15/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Whereas the adverse effects of severe iodine deficiency during pregnancy are well documented, the effects of mild-to-moderate deficiency are not well established. OBJECTIVES We aimed to explore whether iodine nutrition and timing of iodine supplement initiation are associated with thyroid function in pregnant and postpartum women. METHODS In this cohort study, 137 pregnant women were enrolled and followed up at gestational weeks (GWs) 18 and 36, and 3 and 6 mo postpartum. Thyroid function tests [thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4)], urinary iodine and creatinine concentration (UIC:Cr), and iodine intake (including iodine supplement use) were measured at each time point. The associations between thyroid hormone concentrations and UIC:Cr, iodine intakes, and iodine supplement use were estimated using multiple generalized estimating equation models. RESULTS The median UIC at GW18 was 94 μg/L, indicating mild-to-moderate iodine deficiency. UIC:Cr (β; 95% CI) per 100 μg/g was negatively associated with fT3 (-0.191; -0.331, -0.051) and fT4 (-0.756; -1.372, -0.141) concentrations. Iodine intake (β; 95% CI) per 100 μg/d was positively associated with TSH (0.099; 0.022, 0.177), and negatively associated with fT3 (-0.084; -0.0141, -0.027) and fT4 (-0.390; -0.599, -0.182) concentrations. Compared with no use of supplement, those initiating an iodine-containing supplement prepregnancy and continuing through pregnancy had lower TSH (estimated means) (1.35 compared with 1.68 mIU/L, P = 0.021), and higher fT3 (4.48 compared with 4.28 pmol/L, P = 0.035) and fT4 (15.2 compared with 14.4 pmol/L, P = 0.024) concentrations. CONCLUSIONS Lower iodine availability during pregnancy and postpartum was associated with lower TSH, and higher fT3 and fT4 concentrations. The use of an iodine-containing supplement that was initiated prepregnancy and continuing through pregnancy was associated with lower TSH, and higher fT3 and fT4 concentrations, which may suggest improved thyroid function. These findings support the notion that optimization of iodine intake should start before pregnancy.This trial was registered at clinicaltrials.gov as NCT02610959.
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Affiliation(s)
| | - Maria W Markhus
- Seafood, Nutrition and Environmental State, Institute of Marine Research, Bergen, Norway
| | - Tor A Strand
- Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway,Department of Research, Innlandet Hospital Trust, Lillehammer, Norway
| | - Marian Kjellevold
- Seafood, Nutrition and Environmental State, Institute of Marine Research, Bergen, Norway
| | - Lisbeth Dahl
- Seafood, Nutrition and Environmental State, Institute of Marine Research, Bergen, Norway
| | - Ann-Elin M Stokland
- Department of Endocrinology, Stavanger University Hospital, Stavanger, Norway
| | - Bjørn G Nedrebø
- Department of Internal Medicine, Haugesund Hospital, Haugesund, Norway,Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Inger Aakre
- Seafood, Nutrition and Environmental State, Institute of Marine Research, Bergen, Norway
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Martínez-Ibarra A, Martínez-Razo LD, MacDonald-Ramos K, Morales-Pacheco M, Vázquez-Martínez ER, López-López M, Rodríguez Dorantes M, Cerbón M. Multisystemic alterations in humans induced by bisphenol A and phthalates: Experimental, epidemiological and clinical studies reveal the need to change health policies. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 271:116380. [PMID: 33387779 DOI: 10.1016/j.envpol.2020.116380] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 11/21/2020] [Accepted: 12/22/2020] [Indexed: 06/12/2023]
Abstract
A vast amount of evidence indicates that bisphenol A (BPA) and phthalates are widely distributed in the environment since these compounds are mass-produced for the manufacture of plastics and plasticizers. These compounds belong to a large group of substances termed endocrine-disrupting chemicals (EDC). It is well known that humans and living organisms are unavoidably and unintentionally exposed to BPA and phthalates from food packaging materials and many other everyday products. BPA and phthalates exert their effect by interfering with hormone synthesis, bioavailability, and action, thereby altering cellular proliferation and differentiation, tissue development, and the regulation of several physiological processes. In fact, these EDC can alter fetal programming at an epigenetic level, which can be transgenerational transmitted and may be involved in the development of various chronic pathologies later in the adulthood, including metabolic, reproductive and degenerative diseases, and certain types of cancer. In this review, we describe the most recent proposed mechanisms of action of these EDC and offer a compelling selection of experimental, epidemiological and clinical studies, which show evidence of how exposure to these pollutants affects our health during development, and their association with a wide range of reproductive, metabolic and neurological diseases, as well as hormone-related cancers. We stress the importance of concern in the general population and the urgent need for the medical health care system to closely monitor EDC levels in the population due to unavoidable and involuntary exposure to these pollutants and their impact on human health.
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Affiliation(s)
- A Martínez-Ibarra
- Doctorado en Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana, Ciudad de México 04960, Mexico; Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología "Isidro Espinosa de Los Reyes" - Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 11000, Mexico
| | - L D Martínez-Razo
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología "Isidro Espinosa de Los Reyes" - Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 11000, Mexico
| | - K MacDonald-Ramos
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología "Isidro Espinosa de Los Reyes" - Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 11000, Mexico
| | - M Morales-Pacheco
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología "Isidro Espinosa de Los Reyes" - Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 11000, Mexico
| | - E R Vázquez-Martínez
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología "Isidro Espinosa de Los Reyes" - Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 11000, Mexico
| | - M López-López
- Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana, Ciudad de México 04960, Mexico
| | | | - M Cerbón
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología "Isidro Espinosa de Los Reyes" - Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 11000, Mexico.
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12
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Bocco BMLC, Fernandes GW, Fonseca TL, Bianco AC. Iodine Deficiency Increases Fat Contribution to Energy Expenditure in Male Mice. Endocrinology 2020; 161:bqaa192. [PMID: 33091112 PMCID: PMC7707619 DOI: 10.1210/endocr/bqaa192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Indexed: 12/27/2022]
Abstract
More than a billion people worldwide are at risk of iodine deficiency (ID), with well-known consequences for development of the central nervous system. Furthermore, ID has also been associated with dyslipidemia and obesity in humans. To further understand the metabolic consequences of ID, here we kept 8-week-old C57/Bl6 mice at thermoneutrality (~28°C) while feeding them on a low iodine diet (LID). When compared with mice kept on control diet (LID + 0.71 μg/g iodine), the LID mice exhibited marked reduction in T4 and elevated plasma TSH, without changes in plasma T3 levels. LID mice grew normally, and had normal oxygen consumption, ambulatory activity, and heart expression of T3-responsive gene, confirming systemic euthyroidism. However, LID mice exhibited ~5% lower respiratory quotient (RQ), which reflected a ~2.3-fold higher contribution of fat to energy expenditure. LID mice also presented increased circulating levels of nonesterified fatty acids, ~60% smaller fat depots, and increased hepatic glycogen content, all indicative of accelerated lipolysis. LID mice responded much less to forced mobilization of energy substrates (50% food restriction for 3 days or starvation during 36 hours) because of limited size of the adipose depots. A 4-day treatment with T4 restored plasma T4 and TSH levels in LID mice and normalized RQ. We conclude that ID accelerates lipolysis and fatty acid oxidation, without affecting systemic thyroid hormone signaling. It is conceivable that the elevated plasma TSH levels trigger these changes by directly activating lipolysis in the adipose tissues.
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Affiliation(s)
| | | | - Tatiana L Fonseca
- Section of Endocrinology and Metabolism, University of Chicago, Chicago IL
| | - Antonio C Bianco
- Section of Endocrinology and Metabolism, University of Chicago, Chicago IL
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13
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Villanger GD, Drover SSM, Nethery RC, Thomsen C, Sakhi AK, Øvergaard KR, Zeiner P, Hoppin JA, Reichborn-Kjennerud T, Aase H, Engel SM. Associations between urine phthalate metabolites and thyroid function in pregnant women and the influence of iodine status. ENVIRONMENT INTERNATIONAL 2020; 137:105509. [PMID: 32044443 DOI: 10.1016/j.envint.2020.105509] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 01/17/2020] [Accepted: 01/17/2020] [Indexed: 05/23/2023]
Abstract
BACKGROUND Human populations, including susceptible subpopulations such as pregnant women and their fetuses, are continuously exposed to phthalates. Phthalates may affect the thyroid hormone system, causing concern for pregnancy health, birth outcomes and child development. Few studies have investigated the joint effect of phthalates on thyroid function in pregnant women, although they are present as a mixture with highly inter-correlated compounds. Additionally, no studies have investigated if the key nutrient for thyroid health, iodine, modifies these relationships. METHODS In this study, we examined the cross-sectional relationships between concentrations of 12 urinary phthalate metabolites and 6 plasma thyroid function biomarkers measured mid-pregnancy (~17 week gestation) in pregnant women (N = 1072), that were selected from a population-based prospective birth cohort, The Norwegian Mother, Father and Child Cohort study (MoBa). We investigated if the phthalate metabolite-thyroid function biomarker associations differed by iodine status by using a validated estimate of habitual dietary iodine intake based on a food frequency questionnaire from the 22nd gestation week. We accounted for the phthalate metabolite mixture by factor analyses, ultimately reducing the exposure into two uncorrelated factors. These factors were used as predictors in multivariable adjusted linear regression models with thyroid function biomarkers as the outcomes. RESULTS Factor 1, which included high loadings for mono-iso-butyl phthalate (MiBP), mono-n-butyl phthalate (MnBP), and monobenzyl phthalate (MBzP), was associated with increased total triiodothyronine (TT3) and free T3 index (fT3i). These associations appeared to be driven primarily by women with low iodine intake (<150 µg/day, ~70% of our sample). Iodine intake significantly modified (p-interaction < 0.05) the association of factor 1 with thyroid stimulating hormone (TSH), total thyroxine (TT4) and free T4 index (fT4i), such that only among women in the high iodine intake category (≥150 µg/day, i.e. sufficient) was this factor associated with increased TSH and decreased TT4 and FT4i, respectively. In contrast, factor 2, which included high loadings for di-2-ethylhexyl phthalate metabolites (∑DEHP) and di-iso-nonyl phthalate metabolites (∑DiNP), was associated with a decrease in TT3 and fT3i, which appeared fairly uniform across iodine intake categories. CONCLUSION We find that phthalate exposure is associated with thyroid function in mid-pregnancy among Norwegian women, and that iodine intake, which is essential for thyroid health, could influence some of these relationships.
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Affiliation(s)
- Gro D Villanger
- Norwegian Institute of Public Health, PO Box 222 Skøyen, N-0213 Oslo, Norway.
| | - Samantha S M Drover
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina and Chapel Hill, Chapel Hill, NC, USA
| | | | - Cathrine Thomsen
- Norwegian Institute of Public Health, PO Box 222 Skøyen, N-0213 Oslo, Norway
| | - Amrit K Sakhi
- Norwegian Institute of Public Health, PO Box 222 Skøyen, N-0213 Oslo, Norway
| | - Kristin R Øvergaard
- Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - Pal Zeiner
- Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Jane A Hoppin
- Department of Biological Sciences, NC State University, Raleigh, NC, USA
| | - Ted Reichborn-Kjennerud
- Norwegian Institute of Public Health, PO Box 222 Skøyen, N-0213 Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Heidi Aase
- Norwegian Institute of Public Health, PO Box 222 Skøyen, N-0213 Oslo, Norway
| | - Stephanie M Engel
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina and Chapel Hill, Chapel Hill, NC, USA
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Schiller T, Agmon A, Ostrovsky V, Shefer G, Knobler H, Zornitzki T. Moderate Iodine Deficiency Is Common in Pregnancy but Does Not Alter Maternal and Neonatal Thyroid Function Tests. Front Endocrinol (Lausanne) 2020; 11:523319. [PMID: 33362709 PMCID: PMC7759626 DOI: 10.3389/fendo.2020.523319] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 11/11/2020] [Indexed: 01/07/2023] Open
Abstract
INTRODUCTION An Israeli national survey found that 85% of pregnant women had urinary iodine content (UIC) levels below the adequacy range (<150 µg/L). Widespread desalinated water usage and no national fortification plan are possible causes. Studies assessing relationships between iodine status and maternal and neonatal thyroid function provided varying results. Our aims were to determine whether iodine deficiency was associated with altered maternal or neonatal thyroid function and the factors leading to iodine deficiency. METHODS A cross-sectional study including 100 healthy women without prior thyroid disease, in their first trimester of a singleton pregnancy were recruited from an HMO clinic in central Israel. The women were followed from their first trimester. All women completed a 24-h dietary recall and life habits questionnaires. We tested for UIC, maternal and neonatal thyroid function, maternal autoantibodies, and neonatal outcomes. RESULTS Median UIC in our cohort was 49 µg/L [25%-75% interquartile range (IQR) 16-91.5 µg/L], with 84% below adequacy range. No correlation was found between iodine deficiency and maternal or neonatal thyroid function which remained within normal ranges. Antibody status did not differ, but thyroglobulin levels were significantly higher in iodine insufficient subjects. UIC was higher in women consuming an iodine containing supplement. There was no association between UIC and dietary iodine content or water source. CONCLUSIONS Moderate iodine deficiency is common in our healthy pregnant women population. Our data imply that moderate iodine deficiency in pregnancy seem sufficient to maintain normal maternal and neonatal thyroid function.
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Affiliation(s)
- Tal Schiller
- Diabetes, Endocrinology and Metabolic Disease Institute, Kaplan Medical Center, Hebrew University Medical School, Rehovot, Israel
| | - Arnon Agmon
- Clalit Health Services, Lev Tel Aviv Women’s Health Center, Tel Aviv, Israel
| | - Viviana Ostrovsky
- Diabetes, Endocrinology and Metabolic Disease Institute, Kaplan Medical Center, Hebrew University Medical School, Rehovot, Israel
| | - Gabi Shefer
- Tel Aviv Sourasky Medical Center, Institute of Endocrinology, Metabolism and Hypertension, Tel Aviv, Israel
| | - Hilla Knobler
- Diabetes, Endocrinology and Metabolic Disease Institute, Kaplan Medical Center, Hebrew University Medical School, Rehovot, Israel
| | - Taiba Zornitzki
- Diabetes, Endocrinology and Metabolic Disease Institute, Kaplan Medical Center, Hebrew University Medical School, Rehovot, Israel
- *Correspondence: Taiba Zornitzki,
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15
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Levie D, Derakhshan A, Shu H, Broeren MAC, de Poortere RA, Peeters RP, Bornehag CG, Demeneix B, Korevaar TIM. The Association of Maternal Iodine Status in Early Pregnancy with Thyroid Function in the Swedish Environmental Longitudinal, Mother and Child, Asthma and Allergy Study. Thyroid 2019; 29:1660-1668. [PMID: 31524090 DOI: 10.1089/thy.2019.0164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Background: Severe maternal iodine deficiency can impact fetal brain development through effects on maternal and/or fetal thyroid hormone availability. The effects of mild-to-moderate iodine deficiency on thyroid function are less clear. The aim was to investigate the association of maternal urinary iodine concentration corrected for creatinine (UI/Creat) with thyroid function and autoantibodies in a mild-to-moderate iodine-deficient pregnant population. Methods: This study was embedded within the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy (SELMA) study. Clinical reference ranges were determined by the 2.5th and 97.5th population-based percentile cutoffs. The associations of UI/Creat with thyrotropin (TSH), free thyroxine (fT4), free triiodothyronine (fT3), total T4 (TT4), and total T3 (TT3) were studied using multivariable linear regression in thyroid peroxidase antibody (TPOAb)-negative women. The association of UI/Creat with TPOAb and thyroglobulin antibody (TgAb) positivity was analyzed using multivariable logistic regression. Results: Urinary iodine and thyroid function were measured at a median (95% range) gestational age of 10 (6-14) weeks in 2009 women. The median (95% range) UI/Creat was 85 μg/g (36-386) and the UI/Creat was below 150 μg/g in 80.1% of women. Reference ranges did not differ substantially by UI/Creat. A lower UI/Creat was associated with a lower TSH (p = 0.027), a higher TT4 (p = 0.032), and with a corresponding trend toward slightly higher fT4 (p = 0.081), fT3 (p = 0.079), and TT3 (p = 0.10). UI/Creat was not associated with the fT4/fT3 (p = 0.94) or TT4/TT3 ratios (p = 0.63). Women with a UI/Creat of 150-249 μg/g had the lowest prevalence of TPOAb positivity (6.1%), while women with a UI/Creat of <150 μg/g had a higher prevalence (11.0%, odds ratio [OR] confidence interval [95% CI] 1.84 [1.07-3.20], p = 0.029). Women with a UI/Creat ≥500 μg/g showed the highest prevalence and a higher risk of TPOAb positivity, however, only a small proportion of women had such a UI/Creat (12.5%, OR, [95% CI] 2.36 [0.54-10.43], p = 0.26). Conclusions: We could not identify any meaningful differences in thyroid function reference ranges. Lower iodine availability was associated with a slightly lower TSH and a higher TT4. Women with adequate iodine intake had the lowest risk of TPOAb positivity.
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Affiliation(s)
- Deborah Levie
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus MC, Rotterdam, The Netherlands
- The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands
- Department of Child and Adolescent Psychiatry/Psychology, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Arash Derakhshan
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Huan Shu
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
| | - Maarten A C Broeren
- Laboratory of Clinical Chemistry and Haematology, Máxima Medical Centre, Veldhoven, The Netherlands
| | - Ralph A de Poortere
- Laboratory of Clinical Chemistry and Haematology, Máxima Medical Centre, Veldhoven, The Netherlands
| | - Robin P Peeters
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Carl-Gustaf Bornehag
- Department of Health Sciences, Karlstad University, Karlstad, Sweden
- Icahn School of Medicine at Mount Sinai, New York, New York
| | - Barbara Demeneix
- UMR 7221, Laboratoire d'Evolution des Régulations Endocriniennes, CNRS/Muséum National d'Histoire Naturelle, Sorbonne Universities, Paris, France
| | - Tim I M Korevaar
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus MC, Rotterdam, The Netherlands
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16
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Lamichhane TR, Paudel S, Yadav BK, Lamichhane HP. Echo dephasing and heat capacity from constrained and unconstrained dynamics of triiodothyronine nuclear receptor protein. J Biol Phys 2019; 45:107-125. [PMID: 30810960 PMCID: PMC6408566 DOI: 10.1007/s10867-018-9518-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 12/20/2018] [Indexed: 12/26/2022] Open
Abstract
The objective of this study is to observe the echo feature curves, vibrational dephasing, and heat capacity of a protein-hormone system taking thyroid hormone receptor-beta (THR-β) as an example. Constrained and unconstrained molecular dynamics simulations are performed by implementing the theory of velocity reassignments to probe the phase coherent state in terms of echo pulses. The constrained vibrations are incorporated by adjusting rigid bonds to all hydrogen atoms with an integrator parameter of 2 fs/step in order to reduce the degrees of freedom whereas 1 fs/step is used in the free vibrations of the atomic cluster. The nature of temperature auto-correlation functions changes so that echo feature curves also show a distinct nature in the cases of constrained and unconstrained vibrations. There is a large variation in kinetic temperature and internal potential energy in the echo time zone. The temperature rate of change of internal potential energy is the main contributor to the heat capacity of the native state protein-hormone system. The heat capacity of proteins estimated from this technique is in good agreement with the values from experiments. This study shows that triiodothyronine (T3) hormone makes some differences in heat capacity upon binding to the THR-β ligand binding domain (LBD). The physical properties of unliganded THR-β and T3-bound THR-β LBD in the cases of constrained and unconstrained dynamics are observed distinctly under the effect of anharmonicity on the phase coherent state of normal modes and the dephasing time lies in a range of 0.6-0.8 ps when the systems are perturbed suddenly.
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Affiliation(s)
- Tika Ram Lamichhane
- Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal
| | - Sharma Paudel
- Institute of Medicine, Tribhuvan University Teaching Hospital, Maharajgunj, Kathmandu, Nepal
| | - Binod Kumar Yadav
- Institute of Medicine, Tribhuvan University Teaching Hospital, Maharajgunj, Kathmandu, Nepal
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17
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Drover SSM, Villanger GD, Aase H, Skogheim TS, Longnecker MP, Zoeller RT, Reichborn-Kjennerud T, Knudsen GP, Zeiner P, Engel SM. Maternal Thyroid Function During Pregnancy or Neonatal Thyroid Function and Attention Deficit Hyperactivity Disorder: A Systematic Review. Epidemiology 2019; 30:130-144. [PMID: 30299402 PMCID: PMC6359926 DOI: 10.1097/ede.0000000000000937] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder in children, yet its etiology is poorly understood. Early thyroid hormone disruption may contribute to the development of ADHD. Disrupted maternal thyroid hormone function has been associated with adverse neurodevelopmental outcomes in children. Among newborns, early-treated congenital hypothyroidism has been consistently associated with later cognitive deficits. METHODS We systematically reviewed literature on the association between maternal or neonatal thyroid hormones and ADHD diagnosis or symptoms. We searched Embase, Pubmed, Cinahl, PsycInfo, ERIC, Medline, Scopus, and Web of Science for articles published or available ahead of print as of April 2018. RESULTS We identified 28 eligible articles: 16 studies of maternal thyroid hormones, seven studies of early-treated congenital hypothyroidism, and five studies of neonatal thyroid hormones. The studies provide moderate evidence for an association between maternal thyroid hormone levels and offspring ADHD, some evidence for an association between early-treated congenital hypothyroidism and ADHD, and little evidence for an association between neonatal thyroid hormone levels and later ADHD. CONCLUSIONS The reviewed articles suggest an association between maternal thyroid function and ADHD, and possibly between early-treated congenital hypothyroidism and ADHD. Study limitations, however, weaken the conclusions in our systematic review, underlining the need for more research. Importantly, there was much variation in the measurement of thyroid hormone function and of ADHD symptoms. Recommendations for future research include using population-based designs, attending to measurement issues for thyroid hormones and ADHD, considering biologically relevant covariates (e.g., iodine intake), and assessing nonlinear dose-responses.
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Affiliation(s)
- Samantha S M Drover
- From the Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC
| | - Gro D Villanger
- Norwegian Institute of Public Health, Physical and Mental health, Oslo, Norway
| | - Heidi Aase
- Norwegian Institute of Public Health, Physical and Mental health, Oslo, Norway
| | - Thea S Skogheim
- Norwegian Institute of Public Health, Physical and Mental health, Oslo, Norway
| | - Matthew P Longnecker
- National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC
| | - R Thomas Zoeller
- Biology Department, University of Massachusetts-Amherst, Amherst, MA
| | | | - Gun P Knudsen
- Norwegian Institute of Public Health, Physical and Mental health, Oslo, Norway
| | - Pål Zeiner
- Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - Stephanie M Engel
- From the Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC
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18
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Abel MH, Brandlistuen RE, Caspersen IH, Aase H, Torheim LE, Meltzer HM, Brantsaeter AL. Language delay and poorer school performance in children of mothers with inadequate iodine intake in pregnancy: results from follow-up at 8 years in the Norwegian Mother and Child Cohort Study. Eur J Nutr 2018; 58:3047-3058. [PMID: 30417257 PMCID: PMC6842354 DOI: 10.1007/s00394-018-1850-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/29/2018] [Indexed: 11/25/2022]
Abstract
Purpose Some studies indicate that mild-to-moderate iodine deficiency in pregnant women might negatively affect offspring neurocognitive development, including previous results from the Norwegian Mother and Child Cohort study (MoBa) exploring maternally reported child development at age 3 years. The aim of this follow-up study was to investigate whether maternal iodine intake in pregnancy is associated with language and learning at 8 years of age. Methods The study sample includes 39,471 mother–child pairs participating in MoBa with available information from a validated food frequency questionnaire covering the first half of pregnancy and a questionnaire on child neurocognitive development at 8 years. Multivariable regression was used to explore associations of iodine intake from food and supplements with maternally reported child outcomes. Results Maternal iodine intake from food less than ~ 150 µg/day was associated with poorer child language skills (p-overall = 0.013), reading skills (p-overall = 0.019), and writing skills (p-overall = 0.004) as well as poorer school test result in reading (p < 0.001), and increased likelihood of the child receiving special educational services (p-overall = 0.042) (in non-iodine supplement users). Although significant, differences were generally small. Maternal use of iodine supplements in pregnancy was not significantly associated with any of the outcomes. Conclusions Low habitual iodine intake in pregnant women, i.e., lower than the recommended intake for non-pregnant women, was associated with mothers reporting poorer child language, school performance, and increased likelihood of special educational services. We found no indications of benefits or harm of using iodine-containing supplements in pregnancy. Initiating use in pregnancy might be too late. Electronic supplementary material The online version of this article (10.1007/s00394-018-1850-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marianne H Abel
- Division of Infection Control and Environmental Health, Department of Exposure and Environmental Epidemiology, Norwegian Institute of Public Health, Skøyen, P.O. Box 222, 0213, Oslo, Norway
- Department of Nursing and Health Promotion, Faculty of Health Sciences, Oslo Metropolitan University, St. Olavs plass, P.O. Box 4, 0130, Oslo, Norway
- Department of Nutrition, Tine, SA, P.O. Box 25, 0051, Oslo, Norway
| | - Ragnhild E Brandlistuen
- Division of Mental and Physical Health, Norwegian Institute of Public Health, Skøyen, P.O. Box 222, 0213, Oslo, Norway
| | - Ida H Caspersen
- Division of Infection Control and Environmental Health, Department of Exposure and Environmental Epidemiology, Norwegian Institute of Public Health, Skøyen, P.O. Box 222, 0213, Oslo, Norway
| | - Heidi Aase
- Division of Mental and Physical Health, Norwegian Institute of Public Health, Skøyen, P.O. Box 222, 0213, Oslo, Norway
| | - Liv E Torheim
- Department of Nursing and Health Promotion, Faculty of Health Sciences, Oslo Metropolitan University, St. Olavs plass, P.O. Box 4, 0130, Oslo, Norway
| | - Helle Margrete Meltzer
- Division of Infection Control and Environmental Health, Department of Exposure and Environmental Epidemiology, Norwegian Institute of Public Health, Skøyen, P.O. Box 222, 0213, Oslo, Norway
| | - Anne Lise Brantsaeter
- Division of Infection Control and Environmental Health, Department of Exposure and Environmental Epidemiology, Norwegian Institute of Public Health, Skøyen, P.O. Box 222, 0213, Oslo, Norway.
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19
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Abel MH, Korevaar TI, Erlund I, Villanger GD, Caspersen IH, Arohonka P, Alexander J, Meltzer HM, Brantsæter AL. Iodine Intake is Associated with Thyroid Function in Mild to Moderately Iodine Deficient Pregnant Women. Thyroid 2018; 28:1359-1371. [PMID: 30132420 PMCID: PMC6157349 DOI: 10.1089/thy.2018.0305] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Studies indicate that mild to moderate iodine deficiency in pregnancy may have a long-term negative impact on child neurodevelopment. These effects are likely mediated via changes in maternal thyroid function, since iodine is essential for the production of thyroid hormones. However, the impact of iodine availability on thyroid function during pregnancy and on thyroid function reference ranges are understudied. The aim of this study was to investigate the association between iodine intake and thyroid function during pregnancy. DESIGN In a population-based pregnancy cohort including 2910 pregnant women participating in The Norwegian Mother and Child Cohort Study, we explored cross sectional associations of maternal iodine intake measured (1) by a food frequency questionnaire and (2) as iodine concentration in a spot urine sample, with plasma thyroid hormones and antibodies. RESULTS Biological samples were collected in mean gestational week 18.5 (standard deviation 1.3) and diet was assessed in gestational week 22. Median iodine intake from food was 121 μg/day (interquartile range 90, 160), and 40% reported use of iodine-containing supplements in pregnancy. Median urinary iodine concentration (UIC) was 59 μg/L among those who did not use supplements and 98 μg/L in the women reporting current use at the time of sampling, indicating mild to moderate iodine deficiency in both groups. Iodine intake as measured by the food frequency questionnaire was not associated with the outcome measures, while UIC was inversely associated with FT3 (p = 0.002) and FT4 (p < 0.001). Introduction of an iodine-containing supplement after gestational week 12 was associated with indications of lower thyroid hormone production (lower FT4, p = 0.027, and nonsignificantly lower FT3, p = 0.17). The 2.5th and 97.5th percentiles of TSH, FT4, and FT3 were not significantly different by groups defined by calculated iodine intake or by UIC. CONCLUSION The results indicate that mild to moderate iodine deficiency affect thyroid function in pregnancy. However, the differences were small, suggesting that normal reference ranges can be determined based on data also from mildly iodine deficient populations, but this needs to be further studied. Introducing an iodine-containing supplement might temporarily inhibit thyroid hormone production and/or release.
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Affiliation(s)
- Marianne Hope Abel
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
- Department of Nursing and Health Promotion, Faculty of Health Sciences, OsloMet - Oslo Metropolitan University, Oslo, Norway
- Department of Nutrition, Tine SA, Oslo, Norway
| | - Tim I.M. Korevaar
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
- Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Iris Erlund
- Genomics and Biomarkers Unit, National Institute for Health and Welfare, Helsinki, Finland
| | - Gro Dehli Villanger
- Division of Mental and Physical Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Ida Henriette Caspersen
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Petra Arohonka
- Genomics and Biomarkers Unit, National Institute for Health and Welfare, Helsinki, Finland
| | - Jan Alexander
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Helle Margrete Meltzer
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Anne Lise Brantsæter
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
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Hassan I, El-Masri H, Kosian PA, Ford J, Degitz SJ, Gilbert ME. Neurodevelopment and Thyroid Hormone Synthesis Inhibition in the Rat: Quantitative Understanding Within the Adverse Outcome Pathway Framework. Toxicol Sci 2017; 160:57-73. [PMID: 28973696 PMCID: PMC10623382 DOI: 10.1093/toxsci/kfx163] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2023] Open
Abstract
Adequate levels of thyroid hormone (TH) are needed for proper brain development, deficiencies may lead to adverse neurologic outcomes in humans and animal models. Environmental chemicals have been linked to TH disruption, yet the relationship between developmental exposures and decline in serum TH resulting in neurodevelopmental impairment is poorly understood. The present study developed a quantitative adverse outcome pathway where serum thyroxin (T4) reduction following inhibition of thyroperoxidase in the thyroid gland are described and related to deficits in fetal brain TH and the development of a brain malformation, cortical heterotopia. Pregnant rats were exposed to 6-propylthiouracil (PTU 0, 0.1, 0.5, 1, 2, or 3 parts per million [ppm]) from gestational days 6-20, sequentially increasing PTU concentrations in maternal thyroid gland and serum as well as in fetal serum. Dams exposed to 0.5 ppm PTU and higher exhibited dose-dependent decreases in thyroidal T4. Serum T4 levels in the dam were significantly decreased with exposure to 2 and 3 ppm PTU. In the fetus, T4 decrements were first observed at a lower dose of 0.5 ppm PTU. Based on these data, fetal brain T4 levels were estimated from published literature sources, and quantitatively linked to increases in the size of the heterotopia present in the brains of offspring. These data show the potential of in vivo assessments and computational descriptions of biologic responses to predict the development of this structural brain malformation and use of quantitative adverse outcome pathway approach to evaluate brain deficits that may result from exposure to other TH disruptors.
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Affiliation(s)
| | - Hisham El-Masri
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709
| | - Patricia A Kosian
- Mid-Continent Ecology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Duluth, Minnesota 55804
| | - Jermaine Ford
- Analytical Chemistry Research Core/Research Cores Unit, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709
| | - Sigmund J Degitz
- Mid-Continent Ecology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Duluth, Minnesota 55804
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McMullen J, Ghassabian A, Kohn B, Trasande L. Identifying Subpopulations Vulnerable to the Thyroid-Blocking Effects of Perchlorate and Thiocyanate. J Clin Endocrinol Metab 2017; 102:2637-2645. [PMID: 28430972 DOI: 10.1210/jc.2017-00046] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 04/06/2017] [Indexed: 12/17/2022]
Abstract
CONTEXT Common environmental contaminants can disrupt normal thyroid function, which plays essential but varying roles at different ages. OBJECTIVE To evaluate the relationship of perchlorate, thiocyanate, and nitrate, three sodium-iodide symporter (NIS) inhibitors, and thyroid function in different age-sex-stratified populations. DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION This was a cross-sectional analysis of data from the 2009 to 2012 National Health and Nutrition Examination Survey evaluating the exposure to perchlorate, thiocyanate, and nitrate in 3151 participants aged 12 to 80. MAIN OUTCOME MEASURE Blood serum free thyroxine (FT4) as both a continuous and categorical variable. We also assessed blood serum thyroid stimulating hormone. RESULTS Controlling for serum cotinine, body mass index, total daily energy consumption, race/ethnicity, and poverty-to-income ratio, for each log unit increase in perchlorate, FT4 decreased by 0.03 ng/dL in both the general population (P = 0.004) and in all women (P = 0.005), and by 0.06 ng/dL in adolescent girls (P = 0.029), corresponding to 4% and 8% decreases relative to median FT4, respectively. For each log unit increase thiocyanate, FT4 decreased by 0.07 ng/dL in adolescent boys (P = 0.003), corresponding to a 9% decrease relative to median FT4, respectively. CONCLUSIONS Our results indicate that adolescent boys and girls represent vulnerable subpopulations to the thyroid-blocking effects of NIS symporter inhibitors. These results suggest a valuable screening and intervention opportunity.
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Affiliation(s)
- Jenica McMullen
- School of Medicine, New York University, New York, New York 10003
| | - Akhgar Ghassabian
- School of Medicine, New York University, New York, New York 10003
- Department of Pediatrics, School of Medicine, New York University, New York, New York 10003
| | - Brenda Kohn
- School of Medicine, New York University, New York, New York 10003
- Department of Pediatrics, School of Medicine, New York University, New York, New York 10003
| | - Leonardo Trasande
- School of Medicine, New York University, New York, New York 10003
- Department of Pediatrics, School of Medicine, New York University, New York, New York 10003
- Wagner School of Public Service, New York University, New York, New York 10003
- College of Global Public Health, New York University, New York, New York 10003
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Alemu A, Terefe B, Abebe M, Biadgo B. Thyroid hormone dysfunction during pregnancy: A review. Int J Reprod Biomed 2016. [DOI: 10.29252/ijrm.14.11.677] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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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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Ursu HI, Toader OD, Podia-Igna C, Delia CE, Firta AR, Tupea CC, Tudor LM, Gheorghiu ML, Suciu N. IODINE STATUS IN PREGNANT WOMEN AFTER A DECADE OF UNIVERSAL SALT IODIZATION IN ROMANIA. ACTA ENDOCRINOLOGICA-BUCHAREST 2016; 12:161-167. [PMID: 31149082 DOI: 10.4183/aeb.2016.161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Objective To assess iodine status (median urinary iodine concentration) in 118 pregnant women during the third trimester from endemic or non-endemic areas, a decade after implementation of Universal Salt Iodization in Romania. Subjects and methods One hundred and eighteen pregnant women in the third trimester were included in the study group (age range: 16 - 46 years, mean age: 28.78 years). Median urinary iodine concentration (UIC) and body mass index (BMI) were evaluated. Data regarding region of provenance, smoking habits during pregnancy, education level, iodized salt intake, bread intake, iodine supplements, comorbidities (iron deficiency anemia) and birth weight were assessed. Morning urine was collected to measure median UIC. The study was approved by the Local Ethics Committee. Results Median UIC in the study group was 206 mcg/L, reflecting iodine sufficiency during pregnancy. There is a statistically significant difference between pregnant women with and without iodine supplements from rural areas (281.5 versus 196.1 mcg/L, respectively, p=0.023). In the subgroup without iodine supplementation, there was a significant difference between overweight and obese subjects vs. normal weight subjects (232.5 versus 194 mcg/L, p=0.012). Only in the subgroup with a daily intake of less than 5 slices of bread (usually containing iodized salt) we found significant differences between those with and without iodine supplements (245.2 versus 128.3 mcg/L). Iron deficiency anemia was found in 29.66% and 19.49% were current smokers during pregnancy. Conclusions Median UIC in the study group was 206 mcg/L, reflecting iodine sufficiency during pregnancy. The difference between the subgroup with iodine supplements and the subgroup without iodine supplements was not statistically significant, probably due to the excessive consumption of bread and other bakery products which is traditional in Romania.
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Affiliation(s)
- H I Ursu
- "C. I. Parhon" National Institute of Endocrinology, Bucharest, Romania.,"Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - O D Toader
- "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania.,"Alfred Rusescu" Institute for Mother and Child, Bucharest, Romania
| | | | - C E Delia
- "Alfred Rusescu" Institute for Mother and Child, Bucharest, Romania
| | - A R Firta
- "Alfred Rusescu" Institute for Mother and Child, Bucharest, Romania
| | - C C Tupea
- "C. I. Parhon" National Institute of Endocrinology, Bucharest, Romania
| | - L M Tudor
- "Alfred Rusescu" Institute for Mother and Child, Bucharest, Romania
| | - M L Gheorghiu
- "C. I. Parhon" National Institute of Endocrinology, Bucharest, Romania.,"Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - N Suciu
- "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania.,"Alfred Rusescu" Institute for Mother and Child, Bucharest, Romania
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Identification and quantification of electrochemically generated metabolites of thyroxine by means of liquid chromatography/electrospray-mass spectrometry and countergradient liquid chromatography/inductively coupled plasma-mass spectrometry. J Chromatogr A 2015; 1419:81-8. [DOI: 10.1016/j.chroma.2015.09.076] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/22/2015] [Accepted: 09/23/2015] [Indexed: 01/07/2023]
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Gereben B, McAninch EA, Ribeiro MO, Bianco AC. Scope and limitations of iodothyronine deiodinases in hypothyroidism. Nat Rev Endocrinol 2015; 11:642-652. [PMID: 26416219 PMCID: PMC5003781 DOI: 10.1038/nrendo.2015.155] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The coordinated expression and activity of the iodothyronine deiodinases regulate thyroid hormone levels in hypothyroidism. Once heralded as the pathway underpinning adequate thyroid-hormone replacement therapy with levothyroxine, the role of these enzymes has come into question as they have been implicated in both an inability to normalize serum levels of tri-iodothyronine (T3) and the incomplete resolution of hypothyroid symptoms. These observations, some of which were validated in animal models of levothyroxine monotherapy, challenge the paradigm that tissue levels of T3 and thyroid-hormone signalling can be fully restored by administration of levothyroxine alone. The low serum levels of T3 observed among patients receiving levothyroxine monotherapy occur as a consequence of type 2 iodothyronine deiodinase (DIO2) in the hypothalamus being fairly insensitive to ubiquitination. In addition, residual symptoms of hypothyroidism have been linked to a prevalent polymorphism in the DIO2 gene that might be a risk factor for neurodegenerative disease. Here, we discuss how these novel findings underscore the clinical importance of iodothyronine deiodinases in hypothyroidism and how an improved understanding of these enzymes might translate to therapeutic advances in the care of millions of patients with this condition.
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Affiliation(s)
- Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony Street 43, Budapest H-1083, Hungary
| | - Elizabeth A McAninch
- Division of Endocrinology and Metabolism, Rush University Medical Center, 212 Cohn Building, 1735 West Harrison Street, Chicago, IL 60612, USA
| | - Miriam O Ribeiro
- Developmental Disorders Program, Center for Biological and Health Science, Mackenzie Presbyterian University, Rua da Consolação 930, Building 16, São Paulo, SP 01302, Brazil
| | - Antonio C Bianco
- Division of Endocrinology and Metabolism, Rush University Medical Center, 212 Cohn Building, 1735 West Harrison Street, Chicago, IL 60612, USA
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van de Ven AC, Netea-Maier RT, Smit JW, Kusters R, van der Stappen JWJ, Pronk-Admiraal CJ, Buijs MM, Schoenmakers CHH, Koehorst SGA, de Groot MJM, Sweep FCGJ, Hermus ARMM, den Heijer M. Thyrotropin versus age relation as an indicator of historical iodine intake. Thyroid 2015; 25:629-34. [PMID: 25811973 DOI: 10.1089/thy.2014.0574] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND In populations with mild iodine deficiency, the serum level of thyrotropin (TSH) is negatively and the serum free thyroxine (FT4) is positively associated with age. An ongoing decrease of TSH and increase of FT4 can be found after iodine supplementation. The aim of this study was to investigate whether there are current differences in the relation between thyroid function and age in relation to differences in iodine intake in the past. METHODS Eight medical laboratories in several regions of The Netherlands, which are all iodine sufficient at present but with a difference in iodine status in the past, provided the results of all TSH and FT4 measurements performed from 2006 until 2011, resulting in 330,802 TSH and 103,940 FT4 measurements. RESULTS The negative association between TSH and age in the elderly is only present in areas with a historical iodine deficiency (regression coefficients [RC] -0.008, 95% confidence interval [CI] -0.009; -0.007). In the historically iodine-sufficient population, TSH shows no obvious increase or decrease with age. In both the historically iodine-sufficient and iodine-deficient populations, FT4 levels were positively associated with age in the elderly (RC 0.009, 95% CI 0.008; 0.010 and RC 0.008, 95% CI 0.007; 0.010, respectively). CONCLUSIONS There are differences in relation between thyroid function and age between populations with differences in iodine intake in the past, despite an adequate iodine status at present. This raises the question whether the present but also historical iodine status of a population should be taken into account when establishing the reference limits of TSH and FT4.
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Affiliation(s)
- Annenienke C van de Ven
- 1Department of Medicine, Division of Endocrinology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Romana T Netea-Maier
- 1Department of Medicine, Division of Endocrinology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Johannes W Smit
- 1Department of Medicine, Division of Endocrinology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Ron Kusters
- 2Laboratory for Clinical Chemistry and Haematology, Jeroen Bosch Hospital, 's-Hertogenbosch, the Netherlands
| | - Jos W J van der Stappen
- 3Department of Laboratory Medicine, Canisius-Wilhelmina Ziekenhuis, Nijmegen, the Netherlands
| | | | | | | | - Stephan G A Koehorst
- 6Department of Laboratory Medicine, Slingeland Hospital, Doetinchem, the Netherlands
| | | | - Fred C G J Sweep
- 8Department of Laboratory Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Ad R M M Hermus
- 1Department of Medicine, Division of Endocrinology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Martin den Heijer
- 1Department of Medicine, Division of Endocrinology, Radboud University Medical Centre, Nijmegen, the Netherlands
- 9Department of Internal Medicine, Section of Endocrinology, VU Medical Center, Amsterdam, the Netherlands
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Histometric and biochemical properties of the thyroid gland in sheep with high iodine supplementation. ACTA VET BRNO 2014. [DOI: 10.2754/avb201382040405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of this study was to evaluate histometric and biochemical properties of the thyroid gland of sheep supplemented with high doses of iodine. The study was conducted on ewes (n = 12) and gimmers (n = 12) of Sumava mountain sheep; each group was subdivided into two groups (group A and B) of six animals. Feed of group A was supplemented with 3 mg iodine/kg of dry matter; group B was given 5 mg iodine/kg dry matter. The iodine in feed mineral supplement was in the form of calcium iodide. The ewes were at first carrying, subsequently lambing, lactating and finally remained barren. The experiment ended after 11 months, when all animals were slaughtered and a sample of the thyroid gland was taken for histometric examination and determination of iodine content by modified colorimetric method. Prior to the slaughter, blood samples were collected for determination of thyroidal hormones and the thyroid-stimulating hormone in blood serum. Thyroid glands of sheep from group B showed higher thyroid weight, larger follicles, higher percentage of large follicles and lower follicular cells compared to groups A. Normal or lower content of triiodothyronine and thyroxine, lower content of their free fractions and bordering or elevated concentrations of thyroid-stimulating hormone were detected in blood serum of all four groups. This trend can signalize the tendency of lowering activity of the thyroid gland. The results of this long-term study show impacts of higher iodine intake on the structure and function of the thyroid gland in sheep.
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van de Ven AC, Netea-Maier RT, Ross HA, van Herwaarden TAE, Holewijn S, de Graaf J, Kiemeney BLA, van Tienoven D, Wetzels JFM, Smit JW, Sweep FCGJ, Hermus ARMM, den Heijer M. Longitudinal trends in thyroid function in relation to iodine intake: ongoing changes of thyroid function despite adequate current iodine status. Eur J Endocrinol 2014; 170:49-54. [PMID: 24114433 DOI: 10.1530/eje-13-0589] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Several cross-sectional studies on populations with iodine deficiency showed that TSH-levels are negatively associated with age, while in populations with high iodine intake TSH is positively associated with age. The question is whether such an age-thyroid function relation is an ongoing process apparent also in longitudinal studies and whether it reflects an actual iodine deficiency or an iodine insufficiency in the past. METHODS In an area with a borderline iodine status in the past, we studied 980 participants of the Nijmegen Biomedical Study. We measured serum TSH, free thyroxine (FT₄), total triiodothyronine (T₃), peroxidase antibodies, and the urine iodine and creatinine concentration 4 years after our initial survey of thyroid function, in which we reported a negative association between TSH and age. RESULTS within 4 years, TSH decreased by 5.4% (95% ci 2.58.3%) and FT₄ increased by 3.7% (95% ci 2.94.6%). median urinary iodine concentration was 130 μg/l. estimated 24-h iodine excretion was not associated with TSH, T₃, change of TSH, or FT₄ over time or with the presence of antibodies against thyroid peroxidase. Only FT₄ appeared to be somewhat higher at lower urine iodine levels: a 1.01% (95% CI 0.17-1.84%) higher FT₄ for each lower iodine quintile. CONCLUSIONS In this longitudinal study, we found an ongoing decrease in TSH and increase in FT₄ in a previously iodine insufficient population, despite the adequate iodine status at present. This suggests that low iodine intake at young age leads to thyroid autonomy (and a tendency to hyperthyroidism) that persists despite normal iodine intake later in life.
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Bianco AC, Anderson G, Forrest D, Galton VA, Gereben B, Kim BW, Kopp PA, Liao XH, Obregon MJ, Peeters RP, Refetoff S, Sharlin DS, Simonides WS, Weiss RE, Williams GR. American Thyroid Association Guide to investigating thyroid hormone economy and action in rodent and cell models. Thyroid 2014; 24:88-168. [PMID: 24001133 PMCID: PMC3887458 DOI: 10.1089/thy.2013.0109] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND An in-depth understanding of the fundamental principles that regulate thyroid hormone homeostasis is critical for the development of new diagnostic and treatment approaches for patients with thyroid disease. SUMMARY Important clinical practices in use today for the treatment of patients with hypothyroidism, hyperthyroidism, or thyroid cancer are the result of laboratory discoveries made by scientists investigating the most basic aspects of thyroid structure and molecular biology. In this document, a panel of experts commissioned by the American Thyroid Association makes a series of recommendations related to the study of thyroid hormone economy and action. These recommendations are intended to promote standardization of study design, which should in turn increase the comparability and reproducibility of experimental findings. CONCLUSIONS It is expected that adherence to these recommendations by investigators in the field will facilitate progress towards a better understanding of the thyroid gland and thyroid hormone dependent processes.
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Affiliation(s)
- Antonio C. Bianco
- Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, Florida
| | - Grant Anderson
- Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, University of Minnesota Duluth, Duluth, Minnesota
| | - Douglas Forrest
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Valerie Anne Galton
- Department of Physiology and Neurobiology, Dartmouth Medical School, Lebanon, New Hampshire
| | - Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Brian W. Kim
- Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, Florida
| | - Peter A. Kopp
- Division of Endocrinology, Metabolism, and Molecular Medicine, and Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Xiao Hui Liao
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois
| | - Maria Jesus Obregon
- Institute of Biomedical Investigation (IIB), Spanish National Research Council (CSIC) and Autonomous University of Madrid, Madrid, Spain
| | - Robin P. Peeters
- Division of Endocrinology, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Samuel Refetoff
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois
| | - David S. Sharlin
- Department of Biological Sciences, Minnesota State University, Mankato, Minnesota
| | - Warner S. Simonides
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Roy E. Weiss
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois
| | - Graham R. Williams
- Department of Medicine, Imperial College London, Hammersmith Campus, London, United Kingdom
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Avivi A, Nevo E, Cohen K, Sotnichenko N, Hercbergs A, Band M, Davis PJ, Ellis M, Ashur-Fabian O. They live in the land down under: thyroid function and basal metabolic rate in the Blind Mole Rat, Spalax. Endocr Res 2014; 39:79-84. [PMID: 24066698 DOI: 10.3109/07435800.2013.833216] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The Israeli blind subterranean mole rat (Spalax ehrenbergi superspecies) lives in sealed underground burrows under extreme, hypoxic conditions. The four Israeli Spalax allospecies have adapted to different climates, the cool-humid (Spalax galili, 2 n = 52 chromosomes), semihumid (S. golani, 2 n = 54) north regions, warm-humid (S. carmeli, 2 n = 58) central region and the warm-dry S. judaei, 2 n = 60) southern regions. A dramatic interspecies decline in basal metabolic rate (BMR) from north to south, even after years of captivity, indicates a genetic basis for this BMR trait. We examined the possibility that the genetically-conditioned interspecies BMR difference was expressed via circulating thyroid hormone. An unexpected north to south increase in serum free thyroxine (FT4) and total 3, 5, 3'-triiodo-L-thyronine (T3) (p < 0.02) correlated negatively with previously published BMR measurements. The increases in serum FT4 and T3 were symmetrical, so that the T3:FT4 ratio - interpretable as an index of conversion of T4 to T3 in nonthyroidal tissues - did not support relative decrease in production of T3 as a contributor to BMR. Increased north-to-south serum FT4 and T3 levels also correlated negatively with hemoglobin/hematocrit. North-to-south adaptations in spalacids include decreased BMR and hematocrit/hemoglobin in the face of increasing thyroid hormone levels, arguing for independent control of hormone secretion and BMR/hematocrit/hemoglobin. But the significant inverse relationship between thyroid hormone levels and BMR/hematocrit/hemoglobin is also consistent with a degree of cellular resistance to thyroid hormone action that protects against hormone-induced increase in oxygen consumption in a hostile, hypoxic environment.
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Affiliation(s)
- Aaron Avivi
- Institute of Evolution, University of Haifa , Haifa , Israel
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Steinmaus C, Miller MD, Cushing L, Blount BC, Smith AH. Combined effects of perchlorate, thiocyanate, and iodine on thyroid function in the National Health and Nutrition Examination Survey 2007-08. ENVIRONMENTAL RESEARCH 2013; 123:17-24. [PMID: 23473920 PMCID: PMC3857960 DOI: 10.1016/j.envres.2013.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 12/18/2012] [Accepted: 01/28/2013] [Indexed: 05/17/2023]
Abstract
Perchlorate, thiocyanate, and low iodine intake can all decrease iodide intake into the thyroid gland. This can reduce thyroid hormone production since iodide is a key component of thyroid hormone. Previous research has suggested that each of these factors alone may decrease thyroid hormone levels, but effect sizes are small. We hypothesized that people who have all three factors at the same time have substantially lower thyroid hormone levels than people who do not, and the effect of this combined exposure is substantially larger than the effects seen in analyses focused on only one factor at a time. Using data from the 2007-2008 National Health and Nutrition Examination Survey, subjects were categorized into exposure groups based on their urinary perchlorate, iodine, and thiocyanate concentrations, and mean serum thyroxine concentrations were compared between groups. Subjects with high perchlorate (n=1939) had thyroxine concentrations that were 5.0% lower (mean difference=0.40 μg/dl, 95% confidence interval=0.14-0.65) than subjects with low perchlorate (n=2084). The individual effects of iodine and thiocyanate were even smaller. Subjects with high perchlorate, high thiocyanate, and low iodine combined (n=62) had thyroxine concentrations 12.9% lower (mean difference=1.07 μg/dl, 95% confidence interval=0.55-1.59) than subjects with low perchlorate, low thiocyanate, and adequate iodine (n=376). Potential confounders had little impact on results. Overall, these results suggest that concomitant exposure to perchlorate, thiocyanate, and low iodine markedly reduces thyroxine production. This highlights the potential importance of examining the combined effects of multiple agents when evaluating the toxicity of thyroid-disrupting agents.
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Affiliation(s)
- Craig Steinmaus
- Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1515 Clay St. 16 Floor, Oakland, CA 94612; (415) 933-0190
| | - Mark D. Miller
- Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1515 Clay St. 16 Floor, Oakland, CA 94612
| | - Lara Cushing
- Energy & Resources Group, 310 Barrows Hall, University of California, Berkeley, CA 93720-3050
| | - Benjamin C. Blount
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Mail Stop F47, Atlanta, GA
| | - Allan H. Smith
- Arsenic Health Effects Research Group, 1950 Addison St., Suite 204; University of California, Berkeley, CA 94704
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Iodine and mental development of children 5 years old and under: a systematic review and meta-analysis. Nutrients 2013; 5:1384-416. [PMID: 23609774 PMCID: PMC3705354 DOI: 10.3390/nu5041384] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/14/2013] [Accepted: 03/22/2013] [Indexed: 11/17/2022] Open
Abstract
Several reviews and meta-analyses have examined the effects of iodine on mental development. None focused on young children, so they were incomplete in summarizing the effects on this important age group. The current systematic review therefore examined the relationship between iodine and mental development of children 5 years old and under. A systematic review of articles using Medline (1980-November 2011) was carried out. We organized studies according to four designs: (1) randomized controlled trial with iodine supplementation of mothers; (2) non-randomized trial with iodine supplementation of mothers and/or infants; (3) prospective cohort study stratified by pregnant women's iodine status; (4) prospective cohort study stratified by newborn iodine status. Average effect sizes for these four designs were 0.68 (2 RCT studies), 0.46 (8 non-RCT studies), 0.52 (9 cohort stratified by mothers' iodine status), and 0.54 (4 cohort stratified by infants' iodine status). This translates into 6.9 to 10.2 IQ points lower in iodine deficient children compared with iodine replete children. Thus, regardless of study design, iodine deficiency had a substantial impact on mental development. Methodological concerns included weak study designs, the omission of important confounders, small sample sizes, the lack of cluster analyses, and the lack of separate analyses of verbal and non-verbal subtests. Quantifying more precisely the contribution of iodine deficiency to delayed mental development in young children requires more well-designed randomized controlled trials, including ones on the role of iodized salt.
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Lumen A, Mattie DR, Fisher JW. Evaluation of Perturbations in Serum Thyroid Hormones During Human Pregnancy Due to Dietary Iodide and Perchlorate Exposure Using a Biologically Based Dose-Response Model. Toxicol Sci 2013; 133:320-41. [DOI: 10.1093/toxsci/kft078] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Gilbert ME, Hedge JM, Valentín-Blasini L, Blount BC, Kannan K, Tietge J, Zoeller RT, Crofton KM, Jarrett JM, Fisher JW. An Animal Model of Marginal Iodine Deficiency During Development: The Thyroid Axis and Neurodevelopmental Outcome*. Toxicol Sci 2013; 132:177-95. [DOI: 10.1093/toxsci/kfs335] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Lavado-Autric R, Calvo RM, de Mena RM, de Escobar GM, Obregon MJ. Deiodinase activities in thyroids and tissues of iodine-deficient female rats. Endocrinology 2013; 154:529-36. [PMID: 23142811 DOI: 10.1210/en.2012-1727] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Severe iodine deficiency is characterized by goiter, preferential synthesis, and secretion of T(3) in thyroids, hypothyroxinemia in plasma and tissues, normal or low plasma T(3), and slightly increased plasma TSH. We studied changes in deiodinase activities and mRNA in several tissues of rats maintained on low-iodine diets (LIDs) or LIDs supplemented with iodine (LID+I). T(4) and T(3) concentrations decreased in plasma, tissues, and thyroids of LID rats, and T(4) decreased more than T(3) (50%). The highest type 1 iodothyronine deiodinase (D1) activities were found in the thyroid, kidney, and the liver; pituitary, lung, and ovary had lower D1 activities; but the lowest levels were found in the heart and skeletal muscle. D1 activity decreased in all tissues of LID rats (10-40% of LID+I rats), except for ovary and thyroids, which D1 activity increased 2.5-fold. Maximal type 2 iodothyronine deiodinase (D2) activities were found in thyroid, brown adipose tissue, and pituitary, increasing 6.5-fold in thyroids of LID rats and about 20-fold in the whole gland. D2 always increased in response to LID, and maximal increases were found in the cerebral cortex (19-fold), thyroid, brown adipose tissue, and pituitary (6-fold). Lower D2 activities were found in the ovary, heart, and adrenal gland, which increased in LID. Type 3 iodothyronine deiodinase activity was undetectable. Thyroidal Dio1 and Dio2 mRNA increased in the LID rats, and Dio1 decreased in the lung, with no changes in mRNA expression in other tissues. Our data indicate that LID induces changes in deiodinase activities, especially in the thyroid, to counteract the low T(4) synthesis and secretion, contributing to maintain the local T(3) concentrations in the tissues with D2 activity.
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Takeuchi T, Kamasaki H, Yoto Y, Honjo T, Tsugawa S, Hotsubo T, Tsutsumi H. Investigation of iodine deficient state and iodine supplementation in patients with severe motor and intellectual disabilities on long-term total enteral nutrition. Endocr J 2012; 59:697-703. [PMID: 22673532 DOI: 10.1507/endocrj.ej11-0361] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Iodine concentrations of enteral nutrition (EN) formulae available in Japan are very low and long-term total EN (TEN) might result in hypothyroidism due to iodine deficiency (HID). Our aim of this study was to determine the degree of iodine deficiency (ID) and need for iodine supplementation (IS) in patients with severe motor and intellectual disabilities (SMID) on long-term TEN. Thyroid function including urinary iodine concentration (UIC) was monitored, and powdered kelp was provided as a source of iodine supplement. Thirty-five SMID on TEN participated in our study. UIC less than 100 μg /L, representing ID, were detected in 97 % of them. Their TSH ranged from 0.5 to 90 μIU/mL. IS using powdered kelp raised their UIC to the normal range. Thyroid function also recovered in the five hypothyroidism cases, which were diagnosed as HID, was also detected. In Japan, there must be many cases with ID associated with long term TEN. We also discuss the regulation of thyroid function in the iodine deficient state.
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Affiliation(s)
- Takako Takeuchi
- Department of Pediatrics, Sapporo Medical University School of Medicine, Japan.
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Abstract
OBJECTIVE To evaluate the peer-reviewed literature on iodine deficiency and hypothyroxinemia in pregnancy. METHODS We review published studies on isolated hypothyroxinemia in pregnancy, methodology of free thyroxine (T4) assays, impact of iodine deficiency on free T4 levels, and status of ongoing prospective randomized trials of isolated hypothyroxinemia during pregnancy. RESULTS Hypothyroxinemia during pregnancy is common. Studies have demonstrated the pivotal role exerted by maternal T4 on fetal brain development and the negative impact of hypothyroxinemia on neurobehavioral performance in offspring. Two intervention studies have demonstrated a positive effect on neurodevelopment in children of mothers promptly supplemented with iodine compared with the neurodevelopment in children of nonsupplemented mothers. Free T4 assays presently in clinical use have limitations. Preliminary results of the Controlled Antenatal Thyroid Study (CATS) are somewhat mixed, and the National Institutes of Health Maternal Fetal Medicine Thyrotropin Study (TSH Study) will be completed in 2015. Knowledge regarding the impact of isolated hypothyroxinemia has progressed, but major questions remain. An optimal diagnostic test for free T4 during pregnancy (accurate, inexpensive, and widely available) remains elusive. Trimester-specific normative data and normal ranges from different geographic regions do not exist. CONCLUSIONS Data published to date are insufficient to recommend levothyroxine therapy in pregnant women with isolated hypothyroxinemia. Adequate iodine intake should be recommended before conception and early in pregnancy.
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Affiliation(s)
- Roberto Negro
- Division of Endocrinology, V. Fazzi Hospital, 73100, Lecce, Italy.
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Mohácsik P, Zeöld A, Bianco AC, Gereben B. Thyroid hormone and the neuroglia: both source and target. J Thyroid Res 2011; 2011:215718. [PMID: 21876836 PMCID: PMC3163027 DOI: 10.4061/2011/215718] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 05/31/2011] [Accepted: 06/17/2011] [Indexed: 12/15/2022] Open
Abstract
Thyroid hormone plays a crucial role in the development and function of the nervous system. In order to bind to its nuclear receptor and regulate gene transcription thyroxine needs to be activated in the brain. This activation occurs via conversion of thyroxine to T3, which is catalyzed by the type 2 iodothyronine deiodinase (D2) in glial cells, in astrocytes, and tanycytes in the mediobasal hypothalamus. We discuss how thyroid hormone affects glial cell function followed by an overview on the fine-tuned regulation of T3 generation by D2 in different glial subtypes. Recent evidence on the direct paracrine impact of glial D2 on neuronal gene expression underlines the importance of glial-neuronal interaction in thyroid hormone regulation as a major regulatory pathway in the brain in health and disease.
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Affiliation(s)
- Petra Mohácsik
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, H-1083, Hungary
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Di Cosmo C, Liao XH, Dumitrescu AM, Philp NJ, Weiss RE, Refetoff S. Mice deficient in MCT8 reveal a mechanism regulating thyroid hormone secretion. J Clin Invest 2010; 120:3377-88. [PMID: 20679730 DOI: 10.1172/jci42113] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 06/16/2010] [Indexed: 11/17/2022] Open
Abstract
The mechanism of thyroid hormone (TH) secretion from the thyroid gland into blood is unknown. Humans and mice deficient in monocarboxylate transporter 8 (MCT8) have low serum thyroxine (T4) levels that cannot be fully explained by increased deiodination. Here, we have shown that Mct8 is localized at the basolateral membrane of thyrocytes and that the serum TH concentration is reduced in Mct8-KO mice early after being taken off a treatment that almost completely depleted the thyroid gland of TH. Thyroid glands in Mct8-KO mice contained more non-thyroglobulin-associated T4 and triiodothyronine than did those in wild-type mice, independent of deiodination. In addition, depletion of thyroidal TH content was slower during iodine deficiency. After administration of 125I, the rate of both its secretion from the thyroid gland and its appearance in the serum as trichloroacetic acid-precipitable radioactivity was greatly reduced in Mct8-KO mice. Similarly, the secretion of T4 induced by injection of thyrotropin was reduced in Mct8-KO in which endogenous TSH and T4 were suppressed by administration of triiodothyronine. To our knowledge, this study is the first to demonstrate that Mct8 is involved in the secretion of TH from the thyroid gland and contributes, in part, to the low serum T4 level observed in MCT8-deficient patients.
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Affiliation(s)
- Caterina Di Cosmo
- Department of Medicine, University of Chicago, Chicago, Illinois, USA
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41
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The Epidemiology of Environmental Perchlorate Exposure and Thyroid Function: A Comprehensive Review. J Occup Environ Med 2010; 52:653-60. [DOI: 10.1097/jom.0b013e3181e31955] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Melse-Boonstra A, Jaiswal N. Iodine deficiency in pregnancy, infancy and childhood and its consequences for brain development. Best Pract Res Clin Endocrinol Metab 2010; 24:29-38. [PMID: 20172468 DOI: 10.1016/j.beem.2009.09.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Iodine deficiency during foetal development and early childhood is associated with cognitive impairment. Randomised clinical studies in school-aged children encountered in the literature indicate that cognitive performance can be improved by iodine supplementation, but most studies suffer from methodological constraints. Tests to assess cognitive performance in the domains that are potentially affected by iodine deficiency need to be refined. Maternal iodine supplementation in areas of mild-to-moderate iodine deficiency may improve cognitive performance of the offspring, but randomised controlled studies with long-term outcomes are lacking. Studies in infants or young children have not been conducted. The best indicators for iodine deficiency in children are thyroid-stimulating hormone (TSH) in newborns and thyroglobulin (Tg) in older children. Urinary iodine may also be useful but only at the population level. Adequate salt iodisation will cover the requirements of infants and children as well as pregnant women. However, close monitoring remains essential.
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Affiliation(s)
- Alida Melse-Boonstra
- Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, the Netherlands.
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Laurberg P, Cerqueira C, Ovesen L, Rasmussen LB, Perrild H, Andersen S, Pedersen IB, Carlé A. Iodine intake as a determinant of thyroid disorders in populations. Best Pract Res Clin Endocrinol Metab 2010; 24:13-27. [PMID: 20172467 DOI: 10.1016/j.beem.2009.08.013] [Citation(s) in RCA: 277] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
UNLABELLED Depending on the availability of iodine, the thyroid gland is able to enhance or limit the use of iodine for thyroid hormone production. When compensation fails, as in severely iodine-deficient populations, hypothyroidism and developmental brain damage will be the dominating disorders. This is, out of all comparison, the most serious association between disease and the level of iodine intake in a population. In less severe iodine deficiency, the normal thyroid gland is able to adapt and keep thyroid hormone production within the normal range. However, the prolonged thyroid hyperactivity associated with such adaptation leads to thyroid growth, and during follicular cell proliferation there is a tendency to mutations leading to multifocal autonomous growth and function. In populations with mild and moderate iodine deficiency, such multifocal autonomous thyroid function is a common cause of hyperthyroidism in elderly people, and the prevalence of thyroid enlargement and nodularity is high. The average serum TSH tends to decrease with age in such populations caused by the high frequency of autonomous thyroid hormone production. On the other hand, epidemiological studies have shown that hypothyroidism is more prevalent in populations with a high iodine intake. Probably, this is also a complication to thyroid adaptation to iodine intake. Many thyroid processes are inhibited when iodine intake becomes high, and the frequency of apoptosis of follicular cells becomes higher. Abnormal inhibition of thyroid function by high levels of iodine is especially common in people affected by thyroid autoimmunity (Hashimoto's thyroiditis). In populations with high iodine intake, the average serum thyroid-stimulating hormone (TSH) tends to increase with age. This phenomenon is especially pronounced in Caucasian populations with a genetically determined high tendency to thyroid autoimmunity. A small tendency to higher serum TSH may be observed already when iodine intake is brought from mildly deficient to adequate, but there is at present no evidence that slightly elevated serum TSH in elderly people leads to an increase in morbidity and mortality. CONCLUSION Even minor differences in iodine intake between populations are associated with differences in the occurrence of thyroid disorders. Both iodine intake levels below and above the recommended interval are associated with an increase in the risk of disease in the population. Optimally, iodine intake of a population should be kept within a relatively narrow interval where iodine deficiency disorders are prevented, but not higher. Monitoring and adjusting of iodine intake in a population is an important part of preventive medicine.
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Affiliation(s)
- Peter Laurberg
- Department of Endocrinology, Aalborg Hospital, Aarhus University Hospital, DK - 9000 Aalborg, Denmark.
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Gordon RC, Rose MC, Skeaff SA, Gray AR, Morgan KMD, Ruffman T. Iodine supplementation improves cognition in mildly iodine-deficient children. Am J Clin Nutr 2009; 90:1264-71. [PMID: 19726593 DOI: 10.3945/ajcn.2009.28145] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The effects of severe iodine deficiency during critical periods of brain development are well documented. There is little known about the consequences of milder forms of iodine deficiency on neurodevelopment. OBJECTIVE The objective was to determine whether supplementing mildly iodine-deficient children with iodine improves cognition. DESIGN A randomized, placebo-controlled, double-blind trial was conducted in 184 children aged 10-13 y in Dunedin, New Zealand. Children were randomly assigned to receive a daily tablet containing either 150 microg I or placebo for 28 wk. Biochemical, anthropometric, and dietary data were collected from each child at baseline and after 28 wk. Cognitive performance was assessed through 4 subtests from the Wechsler Intelligence Scale for Children. RESULTS At baseline, children were mildly iodine deficient [median urinary iodine concentration (UIC): 63 microg/L; thyroglobulin concentration: 16.4 microg/L]. After 28 wk, iodine status improved in the supplemented group (UIC: 145 microg/L; thyroglobulin: 8.5 microg/L), whereas the placebo group remained iodine deficient (UIC: 81 microg/L; thyroglobulin: 11.6 microg/L). Iodine supplementation significantly improved scores for 2 of the 4 cognitive subtests [picture concepts (P = 0.023) and matrix reasoning (P = 0.040)] but not for letter-number sequencing (P = 0.480) or symbol search (P = 0.608). The overall cognitive score of the iodine-supplemented group was 0.19 SDs higher than that of the placebo group (P = 0.011). CONCLUSIONS Iodine supplementation improved perceptual reasoning in mildly iodine-deficient children and suggests that mild iodine deficiency could prevent children from attaining their full intellectual potential. The trial was registered with the Australia New Zealand Clinical Trials Register as ACTRN12608000222347.
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Affiliation(s)
- Rosie C Gordon
- Department of Human Nutrition, University of Otago, Dunedin, New Zealand
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Ashton K, Hooper L, Harvey LJ, Hurst R, Casgrain A, Fairweather-Tait SJ. Methods of assessment of selenium status in humans: a systematic review. Am J Clin Nutr 2009; 89:2025S-2039S. [PMID: 19420095 DOI: 10.3945/ajcn.2009.27230f] [Citation(s) in RCA: 205] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND To understand the effect of selenium intake on health, it is important to identify sensitive and population-specific biomarkers of selenium status. OBJECTIVE The objective of this systematic review was to assess the usefulness of biomarkers of selenium status in humans. DESIGN The methods included a structured search strategy on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases; formal inclusion and exclusion criteria; data extraction into an Access database; validity assessment; and meta-analysis. RESULTS The data from 18 selenium supplementation studies (of which 9 were randomized controlled trials and 1 was considered to be at low risk of bias) indicate that plasma, erythrocyte, and whole-blood selenium, plasma selenoprotein P, and plasma, platelet, and whole-blood glutathione peroxidase activity respond to changes in selenium intake. Although there is a substantial body of data for plasma selenium, more large, high-quality, randomized controlled trials are needed for this biomarker, as well as for the other biomarkers, to explore the reasons for heterogeneity in response to selenium supplementation. There was insufficient evidence to assess the usefulness of other potential biomarkers of selenium status, including urinary selenium, plasma triiodothyroxine:thyroxine ratio, plasma thyroxine, plasma total homocysteine, hair and toenail selenium, erythrocyte, and muscle glutathione peroxidase activity. CONCLUSIONS For all potentially useful biomarkers, more information is needed to evaluate their strengths and limitations in different population groups, including the effects of varying intakes, the duration of intervention, baseline selenium status, and possible confounding effects of genotype.
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Affiliation(s)
- Kate Ashton
- School of Medicine, Health Policy and Practice, the University of East Anglia, Norwich, United Kingdom
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Gereben B, Zavacki AM, Ribich S, Kim BW, Huang SA, Simonides WS, Zeöld A, Bianco AC. Cellular and molecular basis of deiodinase-regulated thyroid hormone signaling. Endocr Rev 2008; 29:898-938. [PMID: 18815314 PMCID: PMC2647704 DOI: 10.1210/er.2008-0019] [Citation(s) in RCA: 563] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 08/15/2008] [Indexed: 02/06/2023]
Abstract
The iodothyronine deiodinases initiate or terminate thyroid hormone action and therefore are critical for the biological effects mediated by thyroid hormone. Over the years, research has focused on their role in preserving serum levels of the biologically active molecule T(3) during iodine deficiency. More recently, a fascinating new role of these enzymes has been unveiled. The activating deiodinase (D2) and the inactivating deiodinase (D3) can locally increase or decrease thyroid hormone signaling in a tissue- and temporal-specific fashion, independent of changes in thyroid hormone serum concentrations. This mechanism is particularly relevant because deiodinase expression can be modulated by a wide variety of endogenous signaling molecules such as sonic hedgehog, nuclear factor-kappaB, growth factors, bile acids, hypoxia-inducible factor-1alpha, as well as a growing number of xenobiotic substances. In light of these findings, it seems clear that deiodinases play a much broader role than once thought, with great ramifications for the control of thyroid hormone signaling during vertebrate development and metamorphosis, as well as injury response, tissue repair, hypothalamic function, and energy homeostasis in adults.
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Affiliation(s)
- Balázs Gereben
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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47
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Verheesen R, Schweitzer C. Iodine deficiency, more than cretinism and goiter. Med Hypotheses 2008; 71:645-8. [DOI: 10.1016/j.mehy.2008.06.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 06/05/2008] [Accepted: 06/06/2008] [Indexed: 10/21/2022]
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Abstract
New insights on the high prevalence of functional decompensation of the thyroid among newborn and children from several states of India as well as neighbouring countries of Nepal and Bhutan helped to prevent nutritional iodine deficiency and iodine deficiency disorders through country-wide iodized salt prophylaxis. Presently on the basis of scientific studies, salt iodization in India is saving millions of children from neonatal hypothyroidism related psycho-physical retardation.
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Affiliation(s)
- N Kochupillai
- Medical Research, M. S. Ramaiah Medical College and Hospitals, Bangalore, India.
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Vallortigara J, Alfos S, Micheau J, Higueret P, Enderlin V. T3 administration in adult hypothyroid mice modulates expression of proteins involved in striatal synaptic plasticity and improves motor behavior. Neurobiol Dis 2008; 31:378-85. [PMID: 18585460 DOI: 10.1016/j.nbd.2008.05.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 05/16/2008] [Accepted: 05/19/2008] [Indexed: 12/01/2022] Open
Abstract
Adult-onset hypothyroidism is associated with neurological changes such as cognitive dysfunction and impaired learning, which may be related to alterations of synaptic plasticity. We investigate the consequence of adult-onset hypothyroidism on thyroid-mediated transcription events in striatal synaptic plasticity, and the effect of triiodothyronine (T3) replacement. We used hypothyroid mice, treated with propylthiouracil (PTU) and methimazole (MMI), with or without subsequent administration of T3. We evaluated the amount of T3 nuclear receptors (TRalpha1, TRbeta) and striatal plasticity indicators: neurogranin (RC3), Ras homolog enriched in striatum (Rhes), Ca2+/calmodulin-dependent protein kinase (CaMKII), and dopamine- and cAMP-regulated phosphoprotein (DARPP-32). In addition, we assessed hypothyroid mice motor behavior as related to striatum synaptic functions. Hypothyroid mice exhibited significantly reduced TRbeta, RC3 and Rhes expression. T3 administration reversed the expression of TRbeta, RC3, and up-regulated CaMKII levels as well as motor behavior, and decreased DARPP-32 protein phosphorylation. We suggest that thyroid hormone modulation had a major impact on striatal synaptic plasticity of adult mice which produced in turn motor behavior modifications.
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Affiliation(s)
- Julie Vallortigara
- Unité de Nutrition et Neurosciences, Universités Bordeaux 1-Bordeaux 2, Avenue des Facultés, 33405 Talence Cedex, France
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50
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McLanahan ED, Andersen ME, Fisher JW. A biologically based dose-response model for dietary iodide and the hypothalamic-pituitary-thyroid axis in the adult rat: evaluation of iodide deficiency. Toxicol Sci 2008; 102:241-53. [PMID: 18178547 DOI: 10.1093/toxsci/kfm312] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
A biologically based dose-response (BBDR) model was developed for dietary iodide and the hypothalamic-pituitary-thyroid (HPT) axis in adult rats. This BBDR-HPT axis model includes submodels for dietary iodide, thyroid-stimulating hormone (TSH), and the thyroid hormones, T(4) and T(3). The submodels are linked together via key biological processes, including (1) the influence of T(4) on TSH production (the HPT axis negative feedback loop), (2) stimulation of thyroidal T(4) and T(3) production by TSH, (3) TSH upregulation of the thyroid sodium (Na(+))/iodide symporter, and (4) recycling of iodide from metabolism of thyroid hormones. The BBDR-HPT axis model was calibrated to predict steady-state concentrations of iodide, T(4), T(3), and TSH for the euthyroid rat whose dietary intake of iodide was 20 mug/day. Then the BBDR-HPT axis model was used to predict perturbations in the HPT axis caused by insufficient dietary iodide intake, and simulation results were compared to experimental findings. The BBDR-HPT axis model was successful in simulating perturbations in serum T(4), TSH, and thyroid iodide stores for low-iodide diets of 0.33-1.14 mug/day. Model predictions of serum T(3) concentrations were inconsistent with observations in some cases. BBDR-HPT axis model simulations show a steep dose-response relationship between dietary intake of iodide and serum T(4) and TSH when dietary iodide intake becomes insufficient (less than 2 mug/day) to sustain the HPT axis. This BBDR-HPT axis model can be linked with physiologically based pharmacokinetic models for thyroid-active chemicals to evaluate and predict dose-dependent HPT axis alterations based on hypothesized modes of action. To support continued development of this model, future studies should include time course data after perturbation of the HPT axis to capture changes in endogenous iodide, serum TSH, T(4), and T(3).
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Affiliation(s)
- Eva D McLanahan
- University of Georgia, Interdisciplinary Toxicology Program, Athens, Georgia 30602, USA
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