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Ares S, Saenz-Rico B, Arnaez J, Diez-Sebastian J, Omeñaca F, Bernal J. Effects of oral iodine supplementation in very low birth weight preterm infants for the prevention of thyroid function alterations during the neonatal period: results of a randomised assessor-blinded pilot trial and neurodevelopmental outcomes at 24 months. Eur J Pediatr 2022; 181:959-972. [PMID: 34651206 DOI: 10.1007/s00431-021-04288-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 12/21/2022]
Abstract
The trace element iodine (I) is essential for the synthesis of thyroid hormones. Parenteral nutrition solutions, formula milk, and human breast milk contain insufficient iodine to meet recommended intake for preterm infants. Iodine deficiency may affect thyroid function and may be associated with morbidity or neurological outcomes. The primary objective is to assess the evidence that dietary supplementation with iodine affects thyroid function during the neonatal period. The design was a randomised controlled pilot trial. Infants who met the inclusion criteria were enrolled through consecutive sampling and assigned to two different groups. The setting was a Spanish university hospital. Ninety-four patients with very low birth weight (under 1500 g) were included. Intervention group: 30 µg I/kg/day of iodine in oral drops given to 47 infants from their first day of life until hospital discharge. Control group: 47 infants without supplements. Formula and maternal milk samples for the determination of iodine content were collected at 1, 7, 15, 21, 30 days, and at discharge. Blood samples were collected for thyroid hormones. Neurological development was assessed at 2 years of age (Bayley III Test). Infants in the supplemented group reached the recommended levels from the first days of life. The researchers detected the effects of iodine balance on the plasma levels of thyroid hormones measured during the first 12 weeks of age. The trial assessed the impact of the intervention on neurodevelopmental morbidity.Conclusion: Thyroid function is related to iodine intake in preterm infants. Therefore, supplements should be added if iodine intake is found to be inadequate. The analyses found no effects of iodine supplementation on the composite scores for Bayley-III assessments in all major domains. The study results indicate potentially important effects on language development related to low iodine excretion during the first 4 weeks of life What is Known: • Thyroid function is related to iodine intake in preterm infants. • Preterm babies on formula preparations and with exclusive parenteral nutrition are at high risk of iodine deficiency. What is New: • Iodine intake should be monitored during the neonatal period. • Iodine supplements should be added if iodine intake is found to be inadequate.
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Affiliation(s)
- S Ares
- Neonatology Unit, University Hospital LA PAZ, Paseo de la Castellana 261, 28046, Madrid, Spain.
| | - B Saenz-Rico
- Facultad de Educacion, Universidad Complutense, Madrid, Spain
| | - J Arnaez
- Neonatology Unit, Hospital Universitario de Burgos, Burgos, Spain
| | - J Diez-Sebastian
- Biostatistics Department, University Hospital LA PAZ, Paseo de la Castellana 261, 28046, Madrid, Spain
| | - F Omeñaca
- Neonatology Unit, University Hospital LA PAZ, Paseo de la Castellana 261, 28046, Madrid, Spain
| | - J Bernal
- Instituto de Investigaciones Biomédicas, Universidad Autónoma de Madrid, Arturo Duperier 4, Madrid, Spain.,Center for Research On Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
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Montaner-Ramón A, Hernández-Pérez S, Campos-Martorell A, Ballesta-Anguiano M, Clemente-León M, Castillo-Salinas F. Thyroid function in < 32 weeks gestation preterm infants. An Pediatr (Barc) 2022; 96:130-137. [DOI: 10.1016/j.anpede.2020.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 10/29/2020] [Indexed: 10/19/2022] Open
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Montaner-Ramón A, Hernández-Pérez S, Campos-Martorell A, Ballesta-Anguiano M, Clemente-León M, Castillo-Salinas F. [Thyroid function in < 32 weeks gestation preterm infants]. An Pediatr (Barc) 2020; 96:S1695-4033(20)30485-9. [PMID: 33358353 DOI: 10.1016/j.anpedi.2020.10.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 10/29/2020] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION Preterm newborns (PN) have a higher risk of thyroid dysfunction than term newborns (TN). This condition may go unnoticed in neonatal screening due to a late elevation of thyrotropin (TSH) in these patients. OBJECTIVE Evaluate thyroid function in the second week of life in PN of < 32 weeks gestation (WG), and to identify factors associated to its alteration. PATIENTS AND METHODS A retrospective study was performed in neonates of < 32 weeks gestation (WG), in whom thyroid function was determined. An analysis was performed on thyroxine (T4L) and TSH levels, as well as their association with perinatal and neonatal outcomes. RESULTS The study included a total of 358 patients with mean gestational age (GA) of 29.3 weeks, and mean birth weight (BW) 1127 grams. A linear correlation was found between T4L and BW (correlation coefficient (R) 0.356; p < 0.001) and GA (R = 0.442; p < 0.001). TSH values were associated with small for gestational age (SGA 5.3 mU/L [1.5-37]; non-SGA 2.89 mU/L [0.2-19.5]; p < 0.001), inotropic support (Yes 3.98 mU/L [0.6-22.9]; No 3.16 mU/L [0.2-37]; p = 0.019) and BW (R = -0.249; p < 0.001). Nine (2.5%) patients were treated with levothyroxine, of whom six were SGA. CONCLUSIONS Thyroid function analysis in the second week of life helps to identify asymptomatic newborns with risk of thyroid dysfunction. SGA newborns are at higher risk of thyroid function alterations.
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Affiliation(s)
- Alicia Montaner-Ramón
- Servicio de Neonatología, Hospital Universitario Materno-Infantil Vall d'Hebron, Barcelona, España.
| | - Susana Hernández-Pérez
- Servicio de Neonatología, Hospital Universitario Materno-Infantil Vall d'Hebron, Barcelona, España
| | - Ariadna Campos-Martorell
- Unidad de Endocrinología Pediátrica, Hospital Universitario Materno-Infantil Vall d'Hebron, Barcelona, España
| | | | - María Clemente-León
- Unidad de Endocrinología Pediátrica, Hospital Universitario Materno-Infantil Vall d'Hebron, Barcelona, España
| | - Félix Castillo-Salinas
- Servicio de Neonatología, Hospital Universitario Materno-Infantil Vall d'Hebron, Barcelona, España
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Ng SM, Turner MA, Weindling AM. Neurodevelopmental Outcomes at 42 Months After Thyroxine Supplementation in Infants Below 28 Weeks' Gestation: A Randomized Controlled Trial. Thyroid 2020; 30:948-954. [PMID: 32070246 PMCID: PMC7374616 DOI: 10.1089/thy.2019.0293] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: Infants below 28 weeks' gestation have low thyroid hormone plasma levels compared with more mature infants and this may contribute to their risk of developmental disability. We aimed at determining the effect of supplementation with levothyroxine (LT4) for extremely premature infants born below 28 weeks' gestations on neurodevelopmental outcomes at 42 months. Methods: An explanatory double-blind, randomized, placebo-controlled trial consecutively recruited 153 infants below 28 weeks' gestation from 5 neonatal units in the United Kingdom. Infants were either supplemented with LT4 started intravenously during the first 5 days after birth and then changed to oral LT4 when enteral feeds were fully established (8 μg/kg birthweight/day as a single daily dose) or given placebo until 32 weeks' corrected gestational age. Neurodevelopmental outcomes at 42 months (range 40-43) were evaluated in 59 of these infants (30 LT4-supplemented, 29 placebo) by using Bayley III Mental and Psychomotor Developmental Indices. Cognition outcomes was correlated with plasma free thyroxine (fT4) level at 36 weeks and diffusion tensor imaging (DTI) markers. Results: The LT4 supplemented group performed significantly better in motor, language, and cognitive function domains. The mean of the difference between each group (95% confidence intervals [CI], p-value) was motor domain 6.96 ([0.55-13.38], p = 0.034); language domain 8.93 ([0.16-17.70], p = 0.041); and cognition domain 6.35 ([0.14-12.55], p = 0.045). Neurodevelopmental outcome at 42 months had some associations with the trial's primary outcome (subarachnoid space width and motor outcome, p = 0.03), plasma fT4 level at 36 weeks (fT4 and cognition outcome, p = 0.01), and DTI at 36 weeks with cognition outcomes (p > 0.05). Conclusion: Our data suggest that early supplementation with LT4 may improve long-term neurodevelopment in infants born below 28 weeks' gestation, but larger trials are warranted as the current reported improvements shown are not strong enough to warrant a change in practice.
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Affiliation(s)
- Sze May Ng
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
- Department of Paediatrics, Southport and Ormskirk Hospital NHS Trust, Ormskirk, United Kingdom
| | - Mark A. Turner
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - A. Michael Weindling
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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Eerdekens A, Langouche L, Van den Berghe G, Verhaeghe J, Naulaers G, Vanhole C. Review shows that thyroid hormone substitution could benefit transient hypothyroxinaemia of prematurity but treatment strategies need to be clarified. Acta Paediatr 2019; 108:792-805. [PMID: 30537292 DOI: 10.1111/apa.14685] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 10/16/2018] [Accepted: 12/04/2018] [Indexed: 01/06/2023]
Abstract
AIM Thyroid hormones are crucial for foetal and neonatal brain development. This paper provides an overview of the normal role of thyroid hormones in foetal brain development and the pathophysiology of transient hypothyroxinaemia of prematurity (THOP). It also discusses the diagnostic and therapeutic controversies around THOP and looks at directions for future research. METHODS We used the PubMed and Embase databases to identify papers published in English from 1969 to June 2018. This identified 20 papers about the impact of THOP on neurodevelopment and seven randomised controlled trials about therapeutic approaches from 1981-2016. RESULTS THOP has been researched for more than three decades. The impact of temporarily low thyroxine levels, without any increase in pituitary-secreted thyroid-stimulating hormone at a critical timeframe in an infant's brain development, is still debated. Heterogeneity in THOP definitions, difficulties with thyroid hormone assessment, identifying patients at risk and a clear lack of sufficiently powered studies add to the current controversy. There are indications that thyroid hormone substitution might be useful in extremely low gestational age neonates with THOP. CONCLUSION Some preterm infants could benefit from THOP treatment, but more studies are needed to clarify further treatment strategies, including the optimal timing of initiation and duration.
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Affiliation(s)
- An Eerdekens
- Department of Neonatology University Hospitals Leuven KU Leuven Leuven Belgium
| | - Lies Langouche
- Department of Cellular and Molecular Medicine Clinical Division and Laboratory of Intensive Care Medicine KU Leuven Leuven Belgium
| | - Greet Van den Berghe
- Department of Cellular and Molecular Medicine Clinical Division and Laboratory of Intensive Care Medicine KU Leuven Leuven Belgium
| | - Johan Verhaeghe
- Department of Obstetrics & Gynaecology University Hospitals Leuven KU Leuven Leuven Belgium
| | - Gunnar Naulaers
- Department of Neonatology University Hospitals Leuven KU Leuven Leuven Belgium
| | - Christine Vanhole
- Department of Neonatology University Hospitals Leuven KU Leuven Leuven Belgium
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Walsh V, Brown JVE, McGuire W. Iodine supplementation for the prevention of mortality and adverse neurodevelopmental outcomes in preterm infants. Cochrane Database Syst Rev 2019; 2:CD005253. [PMID: 30802939 PMCID: PMC6389353 DOI: 10.1002/14651858.cd005253.pub3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Parenteral nutrition solutions, artificial formulas, and human breast milk contain insufficient iodine to meet recommended intakes for preterm infants. Iodine deficiency may exacerbate transient hypothyroxinaemia in preterm infants and this may be associated with adverse neonatal and longer-term outcomes. OBJECTIVES To assess the evidence from randomised controlled trials that dietary supplementation with iodine reduces mortality and morbidity in preterm infants. SEARCH METHODS We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2018, Issue 1), Ovid MEDLINE, Ovid Embase, Ovid Maternity & Infant Care Database, and CINAHL to February 2018. We searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. SELECTION CRITERIA Randomised or quasi-randomised controlled trials that compared supplementing enteral or parenteral feeds with iodine (as iodide salt) versus placebo or no supplementation in preterm infants. DATA COLLECTION AND ANALYSIS Two review authors independently assessed trial eligibility and risk of bias, and extracted data. We analysed treatment effects as described in the individual trials and reported risk ratios (RR) and risk differences for dichotomous data, and mean differences (MD) for continuous data, with 95% confidence intervals (CI). We used a fixed-effect model in meta-analyses and planned to explore potential causes of heterogeneity in sensitivity analyses. We used the GRADE approach to assess the quality of evidence. MAIN RESULTS Two randomised controlled trials fulfilled the eligibility criteria. Both trials used methods to limit bias including allocation concealment and blinding of clinicians and investigators to the allocated intervention. The trials enrolled 1394 infants. One trial recruited 1273 participants. Most participants were born very preterm (less than 32 weeks' gestation) and about one-third were extremely preterm (less than 28 weeks' gestation). Analyses found no effect of iodine supplementation on mortality before hospital discharge (typical RR 1.01, 95% CI 0.72 to 1.42; 2 studies, 1380 infants) or on neurodevelopmental assessments at two years post-term (Bayley Scales of Infant and Toddler Development, Third Edition main domain composite scores: cognitive: MD -0.30, 95% CI -2.44 to 1.84; motor: MD 0.20, 95% CI -2.15 to 2.55; language: MD -0.10, 95% CI -2.50 to 2.30; 1 study, 1259 infants). There were no differences in the proportion of infants who died or had a composite score less than 85 in any main Bayley domain (RR 1.05, 95% CI 0.94 to 1.17; 1 study, 1259 infants), or had visual impairment (RR 0.63, 95% CI 0.28 to 1.45; 1 study, 1092 infants) or auditory impairment (RR 1.05, 95% CI 0.51 to 2.16; 1 study, 1093 infants). Using GRADE methods, we assessed the evidence for the effects on mortality and neurodevelopment outcomes as high-certainty. AUTHORS' CONCLUSIONS The available trial data, predominantly from one large, high-quality multicentre study published in 2017, do not show any evidence of beneficial effects of iodine supplementation for preterm infants. Given the high certainty of these estimates of effect, further trials of this intervention in this population are unlikely to be considered research priorities.
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Affiliation(s)
- Verena Walsh
- University of YorkCentre for Reviews and DisseminationYorkUKY010 5DD
| | | | - William McGuire
- University of YorkCentre for Reviews and DisseminationYorkUKY010 5DD
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7
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Hung PL, Hsu MH, Yu HR, Wu KLH, Wang FS. Thyroxin Protects White Matter from Hypoxic-Ischemic Insult in the Immature Sprague⁻Dawley Rat Brain by Regulating Periventricular White Matter and Cortex BDNF and CREB Pathways. Int J Mol Sci 2018; 19:ijms19092573. [PMID: 30158497 PMCID: PMC6164053 DOI: 10.3390/ijms19092573] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/20/2018] [Accepted: 08/21/2018] [Indexed: 11/16/2022] Open
Abstract
Background: Periventricular white-matter (WM) injury is a prominent feature of brain injury in preterm infants. Thyroxin (T4) treatment reduces the severity of hypoxic-ischemic (HI)-mediated WM injury in the immature brain. This study aimed to delineate molecular events underlying T4 protection following periventricular WM injury in HI rats. Methods: Right common-carotid-artery ligation, followed by hypoxia, was performed on seven-day-old rat pups. The HI pups were injected with saline, or 0.2 or 1 mg/kg of T4 at 48–96 h postoperatively. Cortex and periventricular WM were dissected for real-time (RT)-quantitative polymerase chain reactions (PCRs), immunoblotting, and for immunofluorescence analysis of neurotrophins, myelin, oligodendrocyte precursors, and neointimal. Results: T4 significantly mitigated hypomyelination and oligodendrocyte death in HI pups, whereas angiogenesis of periventricular WM, observed using antiendothelium cell antibody (RECA-1) immunofluorescence and vascular endothelium growth factor (VEGF) immunoblotting, was not affected. T4 also increased the brain-derived neurotrophic factors (BDNFs), but not the nerve growth factor (NGF) expression of injured periventricular WM. However, phosphorylated extracellular signal regulated kinase (p-ERK) and phosphorylated cyclic adenosine monophosphate response element-binding protein (p-CREB) concentrations, but not the BDNF downstream pathway kinases, p38, c-Jun amino-terminal kinase (c-JNK), or Akt, were reduced in periventricular WM with T4 treatment. Notably, T4 administration significantly increased BDNF and phosphorylated CREB in the overlying cortex of the HI-induced injured cortex. Conclusion: Our findings reveal that T4 reversed BNDF signaling to attenuate HI-induced WM injury by activating ERK and CREB pathways in the cortex, but not directly in periventricular WM. This study offers molecular insight into the neuroprotective actions of T4 in HI-mediated WM injury in the immature brain.
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Affiliation(s)
- Pi-Lien Hung
- Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 33303, Taiwan.
| | - Mei-Hsin Hsu
- Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 33303, Taiwan.
| | - Hong-Ren Yu
- Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 33303, Taiwan.
| | - Kay L H Wu
- Center for Translational Research in Biomedical Sciences, College of Medicine, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University, Kaohsiung 33303, Taiwan.
| | - Feng-Sheng Wang
- Core facility for Phenomics & Diagnostics, Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, No123, Rd Ta-Pei, Niao-Song District, Kaohsiung 33303, Taiwan.
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Iijima S. Current knowledge of transient hypothyroxinemia of prematurity: to treat or not to treat? J Matern Fetal Neonatal Med 2018; 32:2591-2597. [PMID: 29447027 DOI: 10.1080/14767058.2018.1441277] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Thyroid hormones (THs) play a critical role in normal maturation of the developing brain in the fetus and infant. Continuing advances in neonatal medicine have contributed to an increased survival of extremely premature infants with neonatal morbidities. In these infants, thyroid system immaturities, as well as morbidity-related thyroid dysfunction, contribute to transient hypothyroxinemia of prematurity (THOP), which is characterized by very low total and free thyroxine and normal or low thyroid-stimulating hormone (TSH) levels. REVIEW Undoubtedly, low levels of THs with elevated TSH are associated with poor neurodevelopmental outcome. However, continuing debate exists regarding whether THOP is harmful to the developing brain. Moreover, no clear effects of TH treatment on neurodevelopmental outcome in preterm infants with THOP have been demonstrated. THs could have unpredictable effects if given unnecessarily. CONCLUSION The current recommendation is to treat THOP with TH only if THOP is accompanied with TSH elevation.
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Affiliation(s)
- Shigeo Iijima
- a Department of Pediatrics , Hamamatsu University School of Medicine , Hamamatsu , Japan
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9
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Uchiyama A, Kushima R, Watanabe T, Kusuda S. Effect of L-thyroxine supplementation on very low birth weight infants with transient hypothyroxinemia of prematurity at 3 years of age. J Perinatol 2017; 37:602-605. [PMID: 28125093 DOI: 10.1038/jp.2016.266] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/26/2016] [Accepted: 12/13/2016] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To evaluate the effects of levothyroxine (L-T4) supplementation on growth and neurodevelopmental outcomes at 3 years of age in very low birth weight (VLBW) infants with transient hypothyroxinemia of prematurity (THOP). STUDY DESIGN VLBW infants with plasma thyroid-stimulating hormone concentrations <10 mIU l-1 and free thyroxine concentrations <0.8 ng dl-1 were defined as having THOP and randomly assigned to the Treated (20 infants) or Untreated (31 infants) group. The Treated group received L-T4 at a dose of 5 μg kg-1 day-1. Growth and neurodevelopmental outcomes at 3 years of age were compared between the two groups. RESULTS There were no significant differences in body length, body weight or head circumference mean s.d. scores or in neurodevelopmental outcomes between the two groups. CONCLUSION L-T4 supplementation in VLBW infants with THOP demonstrated no beneficial effect at 3 years of age.
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Affiliation(s)
- A Uchiyama
- Department of Neonatal Medicine, Maternal and Perinatal Center, Tokyo Women's Medical University, Tokyo, Japan.,Tokyo Metropolitan Neonatal Research Group, Tokyo, Japan
| | - R Kushima
- Tokyo Metropolitan Neonatal Research Group, Tokyo, Japan.,Department of Neonatology, Tokyo Metropolitan Bokutoh Hospital, Tokyo, Japan
| | - T Watanabe
- Tokyo Metropolitan Neonatal Research Group, Tokyo, Japan.,Department of Neonatology, Tokyo Metropolitan Bokutoh Hospital, Tokyo, Japan
| | - S Kusuda
- Department of Neonatal Medicine, Maternal and Perinatal Center, Tokyo Women's Medical University, Tokyo, Japan.,Tokyo Metropolitan Neonatal Research Group, Tokyo, Japan
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10
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Response to thyrotropin-releasing hormone stimulation tests in preterm infants with transient hypothyroxinemia of prematurity. J Perinatol 2015; 35:725-8. [PMID: 26110495 DOI: 10.1038/jp.2015.67] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 03/12/2015] [Accepted: 05/05/2015] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Whether hormone supplementation is necessary for infants with transient hypothyroxinemia of prematurity (THOP) remains controversial, and further analysis of the hypothalamus-pituitary-thyroid axis of infants with THOP is necessary. STUDY DESIGN Thyrotropin-releasing hormone (TRH) stimulation tests were performed at 2 weeks of age in 50 infants with a gestational age of 30 weeks or less, and the data were analyzed retrospectively. RESULT Subjects were divided into three groups; group A consisted of euthyroid infants, group B consisted of infants with THOP and group C consisted of hypothyroid infants. The basal and peak thyroid-stimulating hormone level of group C in response to TRH stimulation tests was significantly higher than the others, but no differences were observed between groups A and B. CONCLUSION The response of infants with THOP to the TRH stimulation test was not different from that of euthyroid infants, which suggested that their hypothalamic-pituitary-thyroid axis was appropriately regulated in infants with THOP.
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11
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Oh KW, Koo MS, Park HW, Chung ML, Kim MH, Lim G. Establishing a reference range for triiodothyronine levels in preterm infants. Early Hum Dev 2014; 90:621-4. [PMID: 25150803 DOI: 10.1016/j.earlhumdev.2014.07.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 07/16/2014] [Accepted: 07/29/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVES Thyroid dysfunction affects clinical complications in preterm infants and older children. However, thyroid hormone replacement in preterm infants has no proven benefits, possibly owing to the lack of an appropriate reference range for thyroid hormone levels. We aimed to establish a reference range for triiodothyronine (T3) levels at 1-month postnatal age (PNA) in preterm infants. METHODS This retrospective study included preterm infants born at a tertiary referral neonatal center at gestational age (GA)<35 weeks with no apparent thyroid dysfunction, for 6 consecutive years, with follow-up from PNA 2 weeks to 16 weeks. Using thyroid function tests (TFT), the relationships between T3 levels and thyrotropin (TSH) and free thyroxine (fT4) levels, birth weight, GA, postmenstrual age (PMA), and PNA were examined. The conversion trend for fT4 to T3 was analyzed using the T3/fT4 ratio. RESULTS Overall, 464 TFTs from 266 infants were analyzed, after excluding 65 infants with thyroid dysfunction. T3 levels increased with fT4 levels, birth weight, GA, PMA, and PNA but not with TSH levels. The T3/fT4 ratio also increased with GA, PNA, and PMA. The average T3 level at 1 month PNA was 72.56 ± 27.83 ng/dL, with significant stratifications by GA. CONCLUSIONS Relatively low T3 and fT4 levels in preterm infants were considered normal, with T3 levels and conversion trends increasing with GA, PMA, and PNA. Further studies are required to confirm the role of the present reference range in thyroid hormone replacement therapy.
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Affiliation(s)
- Ki Won Oh
- Department of Pediatrics, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea
| | - Mi Sung Koo
- Department of Pediatrics, Maryknoll Medical Center, Busan, South Korea
| | - Hye Won Park
- Department of Pediatrics, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, South Korea
| | - Mi Lim Chung
- Department of Pediatrics, Haeundae Paik Hospital, College of Medicine, Inje University, Busan, South Korea
| | - Min-ho Kim
- Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea
| | - Gina Lim
- Department of Pediatrics, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea.
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12
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Ng SM, Turner MA, Gamble C, Didi M, Victor S, Manning D, Settle P, Gupta R, Newland P, Weindling AM. An explanatory randomised placebo controlled trial of levothyroxine supplementation for babies born <28 weeks' gestation: results of the TIPIT trial. Trials 2013; 14:211. [PMID: 23841945 PMCID: PMC3711854 DOI: 10.1186/1745-6215-14-211] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 07/02/2013] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Babies born before 28 weeks' gestation have lower plasma thyroid hormone concentrations than more mature infants. This may contribute to their risk of poor developmental outcome. Previous studies have suggested that thyroxine supplementation for extremely preterm neonates may be beneficial. The aim of this study was to investigate the effect of administration of supplemental thyroxine to very premature babies on brain size and somatic growth at 36 weeks' corrected gestational age (CGA). METHODS In this explanatory multicentre double blind randomised placebo controlled trial, 153 infants born below 28 weeks' gestation were randomised to levothyroxine (LT4) supplementation or placebo until 32 weeks' CGA. The primary outcome was brain size assessed by the width of the subarachnoid space measured by cranial ultrasound at 36 weeks' CGA. Lower leg length was measured by knemometry. RESULTS Babies in the LT4-supplemented and placebo groups had similar baseline characteristics. There were no significant differences between infants given LT4 (n=78) or placebo (n=75) for width of the subarachnoid space, head circumference at 36 weeks' CGA, body weight at 36 weeks' CGA or mortality. Infants who received LT4 had significantly shorter leg lengths at 36 weeks' CGA although adjusted analysis for baseline length did not find a statistical difference. There was a significant correlation between low FT4 and wider subarachnoid space. No unexpected serious adverse events were noted and incidence of adverse events did not differ between the two groups. CONCLUSION This is the only randomised controlled trial of thyroxine supplementation targeting extremely premature infants. Supplementing all babies below 28 weeks' gestation with LT4 had no apparent effect on brain size. These results do not support routine supplementation with LT4 for all babies born below 28 weeks' gestation. TRIAL REGISTRATION Current Controlled Trials ISRCTN89493983EUDRACT number: 2005-003-09939.
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Affiliation(s)
- Sze M Ng
- Department of Women’s and Children’s Health, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
- Department of Paediatrics, Southport and Ormskirk NHS Trust, Wigan Road, Ormskirk, Lancashire L39 2AZ, UK
| | - Mark A Turner
- Department of Women’s and Children’s Health, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Carrol Gamble
- Clinical Trials Research Centre, University of Liverpool, Liverpool, UK
| | - Mohammed Didi
- Department of Endocrinology, Alder Hey Children’s Foundation Trust, Liverpool, UK
| | - Suresh Victor
- Developmental Biomedicine Research Group, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - Donal Manning
- Neonatal Unit, Wirral Teaching Hospital Foundation Trust, Wirral, UK
| | - Paul Settle
- Neonatal Unit, Salford Royal NHS Foundation Trust, Salford, UK
| | - Richa Gupta
- Neonatal Unit, Royal Preston Hospital, Preston, UK
| | - Paul Newland
- Department of Biochemistry, Alder Hey Children’s Foundation Trust, Liverpool, UK
| | - Alan Michael Weindling
- Department of Women’s and Children’s Health, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
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13
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Hung PL, Huang CC, Huang HM, Tu DG, Chang YC. Thyroxin Treatment Protects Against White Matter Injury in The Immature Brain via Brain-Derived Neurotrophic Factor. Stroke 2013; 44:2275-83. [DOI: 10.1161/strokeaha.113.001552] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Belfort MB, Pearce EN, Braverman LE, He X, Brown RS. Low iodine content in the diets of hospitalized preterm infants. J Clin Endocrinol Metab 2012; 97:E632-6. [PMID: 22337912 PMCID: PMC3319182 DOI: 10.1210/jc.2011-3369] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Iodine is critical for normal thyroid hormone synthesis and brain development during infancy, and preterm infants are particularly vulnerable to the effects of both iodine deficiency and excess. Use of iodine-containing skin antiseptics in intensive care nurseries has declined substantially in recent years, but whether the current dietary iodine intake meets the requirement for hospitalized preterm infants is unknown. OBJECTIVE The aim of the study was to measure the iodine content of enteral and parenteral nutrition products commonly used for hospitalized preterm infants and estimate the daily iodine intake for a hypothetical 1-kg infant. METHODS We used mass spectrometry to measure the iodine concentration of seven preterm infant formulas, 10 samples of pooled donor human milk, two human milk fortifiers (HMF) and other enteral supplements, and a parenteral amino acid solution and soy-based lipid emulsion. We calculated the iodine provided by typical diets based on 150 ml/kg · d of formula, donor human milk with or without HMF, and parenteral nutrition. RESULTS Preterm formula provided 16.4-28.5 μg/d of iodine, whereas unfortified donor human milk provided only 5.0-17.6 μg/d. Adding two servings (six packets) of Similac HMF to human milk increased iodine intake by 11.7 μg/d, whereas adding two servings of Enfamil HMF increased iodine intake by only 0.9 μg/d. The other enteral supplements contained almost no iodine, nor did a parenteral nutrition-based diet. CONCLUSIONS Typical enteral diets for hospitalized preterm infants, particularly those based on donor human milk, provide less than the recommended 30 μg/d of iodine, and parenteral nutrition provides almost no iodine. Additional iodine fortification should be considered.
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Affiliation(s)
- Mandy B Belfort
- Division of Newborn Medicine, Hunnewell 438, Children's Hospital Boston, 300 Longwood Avenue, Boston, Massachusetts 02115, USA.
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15
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Okada J, Iwata S, Hirose A, Kanda H, Yoshino M, Maeno Y, Matsuishi T, Iwata O. Levothyroxine replacement therapy and refractory hypotension out of transitional period in preterm infants. Clin Endocrinol (Oxf) 2011; 74:354-64. [PMID: 21070313 DOI: 10.1111/j.1365-2265.2010.03927.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Recent studies suggest that refractory hypotension from causes other than septicaemia or cardiac failure is common in extremely preterm infants even out of the transitional period. Marked response to low-dose cortisol suggests underlying adrenal insufficiency, although the exact mechanism remains unknown. METHODS To investigate potential triggers for and related short-term outcomes of early-onset (<Day 7) and late-onset (≥Day 7) refractory hypotension, clinical data for 70 infants <30 weeks gestation were assessed. RESULTS The incidence of early-onset refractory hypotension (n=7) was correlated with younger gestational ages <26 weeks (P < 0.05), whereas the incidence of late-onset refractory hypotension (n=14) was correlated with younger gestational ages and levothyroxine supplementation (P<0.05 and 0.01, respectively). The incidence of both early- and late-onset refractory hypotension was correlated with risks of short-term adverse outcomes such as prolonged mechanical ventilation and hospital stay. CONCLUSIONS Levothyroxine supplementation was identified as an independent variable correlated with an increased incidence of refractory hypotension out of the transitional period; as seen in hypothyroidism with Addison's disease, the immature hypothalamic-pituitary-adrenal axis may not respond properly to the increased demand for cortisol, which may precipitate premature infants into refractory hypotension. Following the administration of levothyroxine, preterm infants may have to be carefully monitored for early signs of refractory hypotension.
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Affiliation(s)
- Junichiro Okada
- Department of Paediatrics and Child Health, Kurume University School of Medicine, Kurume, Fukuoka, Japan
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16
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Goldsmit GS, Valdes M, Herzovich V, Rodriguez S, Chaler E, Golombek SG, Iorcansky S. Evaluation and clinical application of changes in thyroid hormone and TSH levels in critically ill full-term newborns. J Perinat Med 2011; 39:59-64. [PMID: 20979446 DOI: 10.1515/jpm.2010.120] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
INTRODUCTION The term "euthyroid sick syndrome" (ESS) has been used to describe a pattern of thyroid hormone changes during the course of critical illness in adult patients without thyroid disease, often associated with reduced thyroid hormone secretion. OBJECTIVE To describe the thyroid hormone profile in full-term newborns critically ill compared with thyroid hormone profile of healthy infants, and determine if alterations could be related to the severity of the disease and outcome. METHODS A cross-sectional, observational, and prospective study of full-term infants admitted to the neonatal intensive care unit (NICU) of the Hospital de Pediatría J.P. Garrahan between July 2007 and April 2008. Serum T3, T4, and thyroid stimulating hormone (TSH) levels were measured at admission and severity of the disease was evaluated through SNAP, lactic acid, respiratory assistance and number of organs affected. RESULTS Sick newborns showed significantly lower T3 and T4 levels compared with healthy infants [T3: -0.97 μg/dL (95% CI -0.89, -1.13) and T4: -4.37 μg/dL (95% CI -2.95, -5.78)]. Only 29 out of 94 (31%) infants presented a normal profile; 37 (39%) infants showed isolated low T3 levels, 20 (21%) infants had low T3 and T4 levels and eight (9%) infants had low TSH, T3, and T4. Of this latter group, five of eight (62%) children died suggesting a significantly higher risk of death for patients with low T3 associated with low T4 and TSH [Risk ratio (RR) 10.75 95% CI 3.93, 29]. CONCLUSIONS Full-term sick newborns frequently have lower thyroid hormone levels than healthy ones. These observed thyroid hormones changes might be related to the underlying disease and could be used as a prognostic marker of the severity and fatal outcome of the patient.
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Affiliation(s)
- Gustavo S Goldsmit
- Neonatology, Hospital Nacional de Pediatria JP Garrahan, Buenos Aires, Argentina
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17
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Ares S, Quero J, Diez J, Morreale de Escobar G. Neurodevelopment of preterm infants born at 28 to 36 weeks of gestational age: the role of hypothyroxinemia and long-term outcome at 4 years. J Pediatr Endocrinol Metab 2011; 24:897-902. [PMID: 22308839 DOI: 10.1515/jpem.2011.166] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
CONTEXT Hypothyroxinemia in premature neonates may affect long-term neurodevelopment. OBJECTIVE This study aimed to examine the effects of hypothyroxinemia of the newborn preterm infants born at 28-36 weeks of gestational age (GA) on the neurodevelopment at 4 years of age. PATIENTS Prospective observational cohort study conducted in Madrid, Spain. Forty-six preterm infants were included in the study. MAIN OUTCOME The effects of the exposure to neonatal hypothyroxinemia on mental development were examined. RESULTS Using regression analyses we found that neonatal T4 had a positive association with general cognitive index and Verbal index, and neonatal FT4 with general cognitive and Memory indexes at 4 years of age. CONCLUSIONS The exposure to hypothyroxinemia during the neonatal period of late preterm infants may play role in neurodevelopmental delays. Higher T4 level means a trend to higher indexes and low T4 level means a lower neurodevelopmental indexes at 4 years of age.
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Affiliation(s)
- Susana Ares
- Neonatology Unit, University Hospital La Paz, Madrid, Spain.
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18
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Williams F, Hume R. The measurement, definition, aetiology and clinical consequences of neonatal transient hypothyroxinaemia. Ann Clin Biochem 2010; 48:7-22. [PMID: 20930033 DOI: 10.1258/acb.2010.010174] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This review focuses on neonatal transient hypothyroxinaemia, a condition characterized by temporary postnatal reductions in concentrations of Total T4 or Free T4, with normal or low concentrations of thyroid stimulating hormone (TSH). There is neither an agreed quantitative definition, nor an agreed mode of measurement for the condition. Transient hypothyroxinaemia is not routinely monitored yet it is thought to affect about 50% of preterm infants; it was thought to be without long-term sequelae but observational studies indicate that neurodevelopment may be compromised. The aetiology of transient hypothyroxinaemia is complex. There are significant contributions from the withdrawal of maternal-placental thyroxine transfer, hypothalamic-pituitary-thyroid immaturity, developmental constraints on the synthesis and peripheral metabolism of iodothyronines and iodine deficiency. It is not possible to distinguish clinically, or from laboratory measurements, whether transient hypothyroxinaemia is an independent condition or simply a consequence of non-thyroidal illness and/or drug usage. An answer to this question is important because studies of thyroid hormone replacement have been instigated, with mixed results. Until the aetiology of transient hypothyroxinaemia is better understood it would seem prudent not to routinely supplement preterm infants with thyroid hormones. Iodine deficiency, non-thyroidal illness and drug usage are the most modifiable risk factors for transient hypothyroxinaemia and are the clear choices for attempts at reducing its incidence. We suggest that transient hypothyroxinaemia in preterm infants is defined as a normal or low TSH concentration in conjunction with a concentration of Total T4, that is ≤10th percentile of cord Total T4 of the equivalent gestational age had the infant remained in utero.
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Affiliation(s)
- Fiona Williams
- Clinical and Population Sciences and Education, Human Brain Development Group, Mackenzie Building, Ninewells Hospital and Medical School Campus, Kirsty Semple Way, Dundee DD2 4BF, UK.
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19
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Abstract
Iodine deficiency (ID) has multiple adverse effects on growth and development due to inadequate thyroid hormone production. Methods for assessment of iodine nutrition in individuals include the urinary iodine concentration (UI), thyroid size and thyroid function tests. The UI measured in several repeat 24-h urine samples can detect inadequate iodine intake in individuals receiving enteral or parenteral nutrition (PN) and allow for iodine supplementation before the onset of hypothyroidism. A daily dose of 1 microg iodine/kg body weight is currently recommended for children receiving PN, but this is far below their requirements. Daily iodine requirements in adults receiving enteral nutrition or PN are estimated to be 70-150 microg, but most PN formulations do not contain iodine. Despite this, ID has been unlikely because absorption from iodine-containing skin antiseptics and other adventitious sources can provide sufficient iodine. However, if chlorhexidine replaces iodine-containing antiseptics for catheter care, ID may occur during long-term PN, and periodic testing of UI and thyroid function may be prudent. Infants may be particularly vulnerable to ID because of their small thyroidal iodine store. In this review, we describe three recent patients (an infant, a child and an adult) who developed ID and thyroid hypofunction during PN.
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Affiliation(s)
- Michael B Zimmermann
- Human Nutrition Laboratory, Swiss Federal Institute of Technology Zürich, Zürich, Switzerland.
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20
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Serum Thyroid Hormone Levels in Preterm Infants Born before 33 Weeks of Gestation and Association of Transient Hypothyroxinemia with Postnatal Characteristics. J Pediatr Endocrinol Metab 2010. [DOI: 10.1515/jpem.2010.145] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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21
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La Gamma EF, van Wassenaer AG, Ares S, Golombek SG, Kok JH, Quero J, Hong T, Rahbar MH, de Escobar GM, Fisher DA, Paneth N. Phase 1 trial of 4 thyroid hormone regimens for transient hypothyroxinemia in neonates of <28 weeks' gestation. Pediatrics 2009; 124:e258-68. [PMID: 19581264 PMCID: PMC2927485 DOI: 10.1542/peds.2008-2837] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Transiently low levels of thyroid hormones occur in approximately 50% of neonates born 24-28 weeks' gestation and are associated with higher rates of cerebral palsy and cognitive impairment. Raising hormone levels shows promise for improving neurodevelopmental outcome. OBJECTIVE To identify whether any of 4 thyroid hormone supplementation regimens could raise T(4) and FT(4) without suppressing TSH (biochemical euthyroidism). METHODS Eligible subjects had gestational ages between 24 07 and 2767 weeks and were randomized <24 hours of birth to one of six study arms (n = 20-27 per arm): placebo (vehicle: 5% dextrose), potassium iodide (30 microg/kg/d) and continuous or bolus daily infusions of either 4 or 8 microg/kg/d of T(4) for 42 days. T(4) was accompanied by 1 microg/kg/d T(3) during the first 14 postnatal days and infused with 1 mg/mL albumin to prevent adherence to plastic tubing. RESULTS FT(4) was elevated in the first 7 days in all hormone-treated subjects; however, only the continuous 8 microg/kg/d treatment arm showed a significant elevation in all treatment epochs (P < .002 versus all other groups). TT(4) remained elevated in the first 7 days in all hormone-treated subjects (P < .05 versus placebo or iodine arms). After 14 days, both 8 microg/kg/d arms as well as the continuous 4 microg/kg/d arm produced a sustained elevation of the mean and median TT(4), >7 microg/dL (90 nM/L; P < .002 versus placebo). The least suppression of THS was achieved in the 4 microg/kg/d T(4) continuous infusion arm. Although not pre-hypothesized, the duration of mechanical ventilation was significantly lower in the continuous 4 microg/kg/d T(4) arm and in the 8 microg/kg/d T(4) bolus arm (P < .05 versus remaining arms). ROP was significantly lower in the combined 4 thyroid hormone treatment arms than in the combined placebo and iodine arms (P < .04). NEC was higher in the combined 8 microg/kg/d arms (P < .05 versus other arms). CONCLUSIONS Elevation of TT(4) with only modest suppression of TSH was associated with trends suggesting clinical benefits using a continuous supplement of low-dose thyroid hormone (4 microg/kg/d) for 42 days. Future trials will be needed to assess the long-term neurodevelopmental effects of such supplementation.
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MESH Headings
- Administration, Oral
- Dose-Response Relationship, Drug
- Drug Therapy, Combination
- Female
- Follow-Up Studies
- Humans
- Hydrocortisone/blood
- Infant, Extremely Low Birth Weight
- Infant, Newborn
- Infant, Premature, Diseases/blood
- Infant, Premature, Diseases/drug therapy
- Infant, Premature, Diseases/mortality
- Infusions, Intravenous
- Iodine/administration & dosage
- Male
- Survival Rate
- Thyroid Function Tests
- Thyrotropin/blood
- Thyroxine/administration & dosage
- Thyroxine/blood
- Thyroxine/deficiency
- Triiodothyronine/administration & dosage
- Triiodothyronine/blood
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Affiliation(s)
- Edmund F La Gamma
- Department of Neonatal-Perinatal Medicine, Regional Neonatal Center, Maria Fareri Children's Hospital at Westchester Medical Center, New York Medical College, Valhalla, New York 10595, USA.
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22
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Griesmaier E, Keller M. Neuroprotective strategies in excitotoxic brain injury: potential applications to the preterm brain. FUTURE NEUROLOGY 2009. [DOI: 10.2217/fnl.09.28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neuronal and oligodendroglial cell death owing to increased glutamate levels plays an important role in the pathophysiology of hypoxic-, ischemic- and inflammation-mediated brain injury as well as in disorders such as epilepsy, Alzheimer’s, Parkinson’s or Huntington’s disease. In addition, excitotoxic brain injury is known to be a major contributing factor to brain injury in preterm infants. Excitotoxicity is characterized as excessive glutamatergic activation of postsynaptic receptors that consequently leads to cell injury and cell death. The major excitatory amino acid neurotransmitter is glutamate. Glutamate plays a key role in brain development, affecting progenitor cell differentiation, proliferation, migration and survival. In physiological conditions the presence of glutamate in the synapse is regulated by ATP-dependent glutamate transporters in neurons and glial cells, with astrocytes being responsible for a major part of glutamate uptake in the brain. In pathologic circumstances the function of the transporters is impaired, leading to glutamate accumulation in the synaptic cleft and in turn excessive activation of postsynaptic glutamate receptors with subsequent massive Ca2+ influx, activation of neuronal nitric oxide synthase, translocation of proapoptotic genes to the mitochondria, mitochondrial dysfunction, release of cytochrome C into the cytosol, activation of caspases and subsequent cell death. Based on the pathogenic concept of an overactivation of the excitatory pathways, glutamate receptors have been a longstanding therapeutic target for rational drug design. This article reviews the pathophysiology of excitotoxic brain injury in the example of preterm brain injury, as well as current research on therapeutic antiexcitotoxic strategies.
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Affiliation(s)
- Elke Griesmaier
- Department of Pediatrics IV, Medical University Innsbruck, Austria, Anichstr. 35, 6020 Innsbruck, Austria
| | - Matthias Keller
- Department of Pediatrics I University Hospital Essen, Hufelandstraße 55, 45147 Essen Germany
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23
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Abstract
Iodine deficiency has multiple adverse effects in humans, termed iodine deficiency disorders, due to inadequate thyroid hormone production. Globally, it is estimated that 2 billion individuals have an insufficient iodine intake, and South Asia and sub-Saharan Africa are particularly affected. However, about 50% of Europe remains mildly iodine deficient, and iodine intakes in other industrialized countries, including the United States and Australia, have fallen in recent years. Iodine deficiency during pregnancy and infancy may impair growth and neurodevelopment of the offspring and increase infant mortality. Deficiency during childhood reduces somatic growth and cognitive and motor function. Assessment methods include urinary iodine concentration, goiter, newborn TSH, and blood thyroglobulin. But assessment of iodine status in pregnancy is difficult, and it remains unclear whether iodine intakes are sufficient in this group, leading to calls for iodine supplementation during pregnancy in several industrialized countries. In most countries, the best strategy to control iodine deficiency in populations is carefully monitored universal salt iodization, one of the most cost-effective ways to contribute to economic and social development. Achieving optimal iodine intakes from iodized salt (in the range of 150-250 microg/d for adults) may minimize the amount of thyroid dysfunction in populations. Ensuring adequate iodine status during parenteral nutrition has become important, particularly in preterm infants, as the use of povidone-iodine disinfectants has declined. Introduction of iodized salt to regions of chronic iodine deficiency may transiently increase the incidence of thyroid disorders, but overall, the relatively small risks of iodine excess are far outweighed by the substantial risks of iodine deficiency.
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Affiliation(s)
- Michael B Zimmermann
- Laboratory for Human Nutrition, Swiss Federal Institute of Technology Zürich, Schmelzbergstrasse 7, LFV E19, CH-8092 Zürich, Switzerland.
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24
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Abstract
Continuing advances in the care of premature infants has contributed to the increased survival of very low birth weight premature infants. These infants are characterized by a variety of organ and physiological systems immaturities predisposing to deficiencies of postnatal adaptation and a high prevalence of neonatal morbidities. These morbidities have a major impact on postnatal mental and neurological outcomes. Thyroid hormones play a critical role in central nervous system development and function, and thyroid system immaturities as well as morbidity-related thyroid dysfunction (the nonthyroidal illness syndrome) contribute to the transient hypothyroxinemia of premature infants (THOP). Several studies have demonstrated a correlation of THOP with subsequent low IQ and neurologic sequelae in very low birth weight premature infants, and there is suggestive evidence that thyroid hormone supplementation in very low birth weight infants can improve mental outcome. Here, we review normal fetal thyroid system development and the system immaturities contributing to THOP and predisposing to nonthyroidal illness in very low birth weight infants.
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25
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Ares S, Quero J, de Escobar GM. Iodine balance, iatrogenic excess, and thyroid dysfunction in premature newborns. Semin Perinatol 2008; 32:407-12. [PMID: 19007678 DOI: 10.1053/j.semperi.2008.09.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Iodine is a trace element that is essential for the synthesis of thyroid hormones. The thyroid hormones, thyroxine and 3,5,3'-triiodothyronine, are necessary for adequate growth and development throughout fetal and extrauterine life. The iodine intake of newborns is entirely dependent on the iodine content of breast milk and the formula preparations used to feed them. An inadequate iodine supply (deficiency and excess) might be especially dangerous in the case of premature babies. The minimum recommended dietary allowance is different depending on age groups. The iodine intake required is at least 15 microg/kg/d in full-term infants and 30 microg/kg/d in preterms. Premature infants are in a situation of iodine deficiency, precisely at a stage of psychomotor and neural development that is extremely sensitive to alterations of thyroid function.
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Affiliation(s)
- Susana Ares
- Neonatology Unit, University Hospital La Paz, Paseo Castellana, Madrid, Spain.
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26
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Abstract
Deficiency of thyroid hormone during critical periods of development can severely damage the nervous system, but the specific effects of thyroid hormones on neuromotor development are less certain. Nonetheless, evidence has accumulated to suggest that thyroid hormone deficiency might be one cause of cerebral palsy (CP). The evidence arises from three sets of observations: first, severely premature infants with transient hypothyroxinemia have elevated risks of CP; second, some children born with endemic cretinism in iodine-deficient areas of the world have motor findings compatible with the diagnosis of CP; and third, several studies of the antecedents of CP have encountered a higher than expected prevalence of maternal thyroidal disorders. The evidence thus far is insufficient to conclusively determine what role, if any, thyroid hormone deficiency plays in CP, although it seems clear that neuromotor abnormalities can be the result of insufficient supply of maternal thyroid hormone in utero. A major research priority should be to assess the effects on CP risk of thyroid supplementation in transient hypothyroxinemia of prematurity. Iodine deficiency can be addressed by inexpensive and well-established public health measures, and thyroid hormone deficiency can be addressed by inexpensive and well-established clinical measures. If a causal chain can be established that links iodine and thyroid hormone to risk of CP, the potential for introducing very cost-effective ways of reducing the burden of CP will be considerable.
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Affiliation(s)
- Ting Hong
- Department of Epidemiology, College of Human Medicine, Michigan State University, East Lansing, MI, USA
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27
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Rovet J, Simic N. The role of transient hypothyroxinemia of prematurity in development of visual abilities. Semin Perinatol 2008; 32:431-7. [PMID: 19007682 DOI: 10.1053/j.semperi.2008.09.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Preterm birth is associated with an increased risk of visual impairment. However, not all visual deficits can be fully explained by the typical prematurity morbidity factors. In addition, children born preterm often exhibit transient hypothroxinemia of prematurity (THOP) due to premature severing of the maternal supply of thyroid hormones. Because thyroid hormone is critically needed for multiple facets of early brain development, including the structures needed for visual processing, and because the maternal thyroid supply is essential throughout pregnancy, it is possible that THOP contributes to the visual impairments seen in preterm children. To test this hypothesis, we used both clinical tests and visual-evoked potential techniques to assess visual abilities in two cohorts of preterm infants whose thyroid hormone levels were measured in the perinatal period. In the first cohort born 30 to 35 weeks gestation, we found associations between low thyroid hormone levels and reduced visual attention at 3 months corrected age (Study 1) and poor visuomotor abilities at 12 and 18 months corrected age (Study 2). In the second cohort born 23 to 35 weeks gestation, THOP severity was negatively correlated with attention at 3 months corrected age (Study 3) and contrast sensitivity and color vision at 6 months corrected age (Study 4). These findings therefore suggest that thyroid hormone is necessary for the development of early visual abilities and that THOP may partially explain the visual deficits of preterm infants.
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Affiliation(s)
- Joanne Rovet
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada.
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28
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van Wassenaer AG, Kok JH. Trials with thyroid hormone in preterm infants: clinical and neurodevelopmental effects. Semin Perinatol 2008; 32:423-30. [PMID: 19007681 DOI: 10.1053/j.semperi.2008.09.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A large number of articles exist on thyroid hormone function and its clinical correlates, but only a few exist on trials with thyroid hormones in premature infants. Most of these trials had clinical short-term endpoints, while only one trial had a long-term neurodevelopmental endpoint. None of the trials reported changes in mortality and morbidities. A trend toward a lower occurrence of patent ductus arteriosus is found in thyroid hormone treated infants. A gestational age-dependent effect of thyroxine on neurodevelopmental outcome was found in post-hoc subgroup analyses up until the age of 10 years. Thyroxine treatment was associated with improved mental, motor, and neurological outcomes in infants <28 weeks gestation, but with worse mental and neurological outcome in infants of 29 weeks gestation. Future trials should focus on neurodevelopmental outcomes. Continuous administration of thyroid hormone may be more effective than bolus administration.
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Affiliation(s)
- Aleid G van Wassenaer
- Department of Neonatology, Emma Childrens' Hospital Academic Medical Center, Amsterdam, The Netherlands.
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29
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30
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Abstract
Infants born at extreme prematurity are at a high risk of developmental disability. A major risk factor for disability is having a low level of thyroid hormone, described as hypothyroxinemia, which is recognized to be a frequent phenomenon in these infants. At present, there is uncertainty among clinicians regarding the most appropriate method of managing hypothyroxinemia of prematurity. The literature suggests that some, but not all, forms of thyroid supplementation may reduce the incidence of disability in infants born at extreme prematurity. There is a pressing need to confirm the benefit of treatment and to establish the optimal way to treat transient hypothyroxinemia in these infants.
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Affiliation(s)
- Sze May Ng
- a School of Reproductive and Developmental Sciences, University of Liverpool, University Department, 1st Floor, Liverpool Women's Hospital, Crown Street, Liverpool L8 7SS, UK.
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31
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Ng SM, Turner MA, Gamble C, Didi M, Victor S, Malamateniou C, Parkes LM, Tietze A, Gregory L, Sluming V, Abernethy L, Weindling AM. TIPIT: a randomised controlled trial of thyroxine in preterm infants under 28 weeks gestation: magnetic resonance imaging and magnetic resonance angiography protocol. BMC Pediatr 2008; 8:26. [PMID: 18590560 PMCID: PMC2464591 DOI: 10.1186/1471-2431-8-26] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 06/30/2008] [Indexed: 11/10/2022] Open
Abstract
Background Infants born at extreme prematurity are at high risk of developmental disability. A major risk factor for disability is having a low level of thyroid hormone described as hypothyroxinaemia, which is recognised to be a frequent phenomenon in these infants. Derangements of critical thyroid function during the sensitive window in prematurity when early development occurs, may have a range of long term effects for brain development. Further research in preterm infants using neuroimaging techniques will increase our understanding of the specificity of the effects of hypothyroxinaemia on the developing foetal brain. This is an explanatory double blinded randomised controlled trial which is aimed to assess the effect of thyroid hormone supplementation on brain size, key brain structures, extent of myelination, white matter integrity and vessel morphology, somatic growth and the hypothalamic-pituitary-adrenal axis. Methods The study is a multi-centred double blinded randomised controlled trial of thyroid hormone supplementation in babies born below 28 weeks' gestation. All infants will receive either levothyroxine or placebo until 32 weeks corrected gestational age. The primary outcomes will be width of the sub-arachnoid space measured using cranial ultrasound and head circumference at 36 weeks corrected gestational age. The secondary outcomes will be thyroid hormone concentrations, the hypothalamic pituitary axis status and auxological data between birth and expected date of delivery; thyroid gland volume, brain size, volumes of key brain structures, extent of myelination and brain vessel morphology at expected date of delivery and markers of morbidity which include duration of mechanical ventilation and/or oxygen requirement and chronic lung disease. Trial registration Current Controlled Trials ISRCTN89493983
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Affiliation(s)
- Sze M Ng
- School of Reproductive and Developmental Medicine, University of Liverpool, Liverpool, UK.
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Ng SM, Turner MA, Gamble C, Didi M, Victor S, Weindling AM. TIPIT: A randomised controlled trial of thyroxine in preterm infants under 28 weeks' gestation. Trials 2008; 9:17. [PMID: 18366798 PMCID: PMC2335090 DOI: 10.1186/1745-6215-9-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Accepted: 03/26/2008] [Indexed: 05/25/2023] Open
Abstract
BACKGROUND Infants born at extreme prematurity (below 28 weeks' gestation) are at high risk of developmental disability. A major risk factor for disability is having a low level of thyroid hormone which is recognised to be a frequent phenomenon in these infants. At present it is unclear whether low levels of thyroid hormone are a cause of disability, or a consequence of concurrent adversity. METHODS We propose an explanatory multi-centre double blind randomised controlled trial of thyroid hormone supplementation in babies born below 28 weeks' gestation. All infants will receive either levothyroxine or placebo until 32 weeks' corrected gestational age. The primary outcome will be brain growth. This will be assessed by the width of the sub-arachnoid space measured using cranial ultrasound and head circumference at 36 weeks' corrected gestational. The secondary outcomes will be (a) thyroid hormone concentrations measured at increasing postnatal age, (b) status of the hypothalamic pituitary axis, (c) auxological data between birth and 36 weeks' corrected gestational age, (d) thyroid gland volume, (e) volumes of brain structures (measured by magnetic resonance imaging), (f) determination of the extent of myelination and white matter integrity (measured by diffusion weighted MRI) and brain vessel morphology (measured by magnetic resonance angiography) at expected date of delivery and (g) markers of morbidity including duration of mechanical ventilation and chronic lung disease.We will also examine how activity of the hypothalamic-pituitary-adrenal axis modulates the effects of thyroid supplementation. This will contribute to decisions about which confounding variables to assess in large-scale studies. TRIAL REGISTRATION Current Controlled Trials ISRCTN89493983.
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Affiliation(s)
- Sze M Ng
- School of Reproductive and Developmental Medicine, University of Liverpool, Liverpool, UK.
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Abstract
During the functional ontogenesis of the thyroid gland an increasing number of transcription factors play fundamental roles in thyroid-cell differentiation, maintenance of the differentiated state, and thyroid-cell proliferation. The early growth and development of the fetal thyroid appears to be generally independent of thyroid-stimulating hormone (TSH). TSH and thyroxine (T4) levels increase from the 12th week of gestation until delivery, whereas triiodothyronine (T3) levels remain relatively low. At birth, a cold-stimulated short-lived TSH surge is observed, followed by a TSH decrease until day 3 or 4 of life by T4 feedback inhibition. Disorders of thyroid gland development and/or function are relatively common, affecting approximately one newborn infant in 2000-4000. The most prevalent disease, congenital hypothyroidism, is frequently caused by genetic defects of transcription factors involved in the development of the thyroid or pituitary gland. A major cause of congenital hyperthyroidism is the transplacental passage of stimulating thyrotropin antibodies from the mother to the fetus. Hypothyroxinaemia or hypotriiodthyroninaemia is frequently observed in preterm infants with or without severe non-thyroidal illness. Whereas congenital hypo- and hyperthyroidism may be treated successfully with T4 or thyrostatic drugs, there is still insufficient evidence on whether the use of T4 for treatment of the latter condition results in changes in neonatal morbidity or reductions in neurodevelopmental impairment.
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Affiliation(s)
- Juergen Kratzsch
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital, Paul-List-Str. 13-15, D-04103 Leipzig, Germany.
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Zoeller RT, Tan SW, Tyl RW. General background on the hypothalamic-pituitary-thyroid (HPT) axis. Crit Rev Toxicol 2007; 37:11-53. [PMID: 17364704 DOI: 10.1080/10408440601123446] [Citation(s) in RCA: 262] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This article reviews the thyroid system, mainly from a mammalian standpoint. However, the thyroid system is highly conserved among vertebrate species, so the general information on thyroid hormone production and feedback through the hypothalamic-pituitary-thyroid (HPT) axis should be considered for all vertebrates, while species-specific differences are highlighted in the individual articles. This background article begins by outlining the HPT axis with its components and functions. For example, it describes the thyroid gland, its structure and development, how thyroid hormones are synthesized and regulated, the role of iodine in thyroid hormone synthesis, and finally how the thyroid hormones are released from the thyroid gland. It then progresses to detail areas within the thyroid system where disruption could occur or is already known to occur. It describes how thyroid hormone is transported in the serum and into the tissues on a cellular level, and how thyroid hormone is metabolized. There is an in-depth description of the alpha and beta thyroid hormone receptors and their functions, including how they are regulated, and what has been learned from the receptor knockout mouse models. The nongenomic actions of thyroid hormone are also described, such as in glucose uptake, mitochondrial effects, and its role in actin polymerization and vesicular recycling. The article discusses the concept of compensation within the HPT axis and how this fits into the paradigms that exist in thyroid toxicology/endocrinology. There is a section on thyroid hormone and its role in mammalian development: specifically, how it affects brain development when there is disruption to the maternal, the fetal, the newborn (congenital), or the infant thyroid system. Thyroid function during pregnancy is critical to normal development of the fetus, and several spontaneous mutant mouse lines are described that provide research tools to understand the mechanisms of thyroid hormone during mammalian brain development. Overall this article provides a basic understanding of the thyroid system and its components. The complexity of the thyroid system is clearly demonstrated, as are new areas of research on thyroid hormone physiology and thyroid hormone action developing within the field of thyroid endocrinology. This review provides the background necessary to review the current assays and endpoints described in the following articles for rodents, fishes, amphibians, and birds.
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Affiliation(s)
- R Thomas Zoeller
- Biology Department, Morrill Science Center, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, USA.
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Sárközy G, Griesmaier E, He X, Kapelari K, Urbanek M, Simbruner G, Gressens P, Keller M. T3 replacement does not prevent excitotoxic cell death but reduces developmental neuronal apoptosis in newborn mice. Eur J Paediatr Neurol 2007; 11:129-35. [PMID: 17222575 DOI: 10.1016/j.ejpn.2006.11.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Revised: 11/26/2006] [Indexed: 12/11/2022]
Abstract
BACKGROUND Periventricular leukomalacia (PVL) is a major cause of neurological handicap in pre-term infants. At present, there are no effective or causal therapies available. Thyroid hormones play an essential role in brain development and are reported to be decreased in pre-terms and following brain injury in adults. HYPOTHESIS Excitotoxic brain damage of newborn mice decreases thyroid hormone concentrations. Exogenous T3 administration restores thyroid hormone levels and reduces perinatal brain damage in an animal model of PVL. DESIGN AND METHOD To create white and gray matter (WM/GM) lesion mimicking several key aspects of PVL, we injected ibotenic acid (Ibo), a glutamate analog, into the right hemisphere (intracranially (i.c.)) of 5-day-old mice. T3 (10 microg/kg body weight (bw)) was injected intraperitoneally (i.p.) 1 h or repeatedly 1/24/48/72/96 h post-insult. We determined lesion size, number of apoptotic cells in WM/GM and serum T3/T4 concentration at 24 and 120 h after injury. Serum T3/T4 concentration was also determined before and 1 and 2h after T3 administration. RESULTS Excitotoxic brain damage did not alter serum T3/T4 concentrations within 120 h of injury. Serum T3 levels were distinctly elevated within 1 h of T3 injection; however, this elevation was relatively short-lived (half-life estimated to be less than 12 h). Neither single nor repetitive T3 treatment regimen reduced excitotoxic lesion size, but it did reduce apoptosis. CONCLUSIONS T3 replacement does not prevent excitotoxic cell death, but it does reduce developmental neuronal apoptosis, which could participate to the beneficial neuropsychological effects of hormone therapy. Further study is therefore warranted.
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Affiliation(s)
- Gergely Sárközy
- Department of Paediatrics IV, Neonatology, Neuropediatrics and Metabolic Diseases, Medical University Innsbruck, Anichstrasse 35, Innsbruck, Austria
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Cartault Grandmottet A, Cristini C, Tricoire J, Rolland M, Tauber MT, Salles JP. Évaluation des taux de TSH, T4L, T3T des nouveau-nés prématurés et à terme hospitalisés. Arch Pediatr 2007; 14:138-43. [PMID: 17140778 DOI: 10.1016/j.arcped.2006.10.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Accepted: 10/12/2006] [Indexed: 10/23/2022]
Abstract
UNLABELLED Thyroid hormones are essential for foetus and newborn development. Preterm newborns present low levels for thyroid hormones. These low levels are related with disorder in psychomotor and neurological development. In the literature, several studies concerning newborns treated with thyroid hormone have been realized in different conditions; however, there is no consensus about preterm newborn supplementation benefit. OBJECTIVE The aim of the study was to defined hormonal values used for normal and preterm newborns. MATERIAL AND METHODS We reported TSH, T3T and T4L levels for 195 normal or preterm newborns, eutrophic or small for gestational age (SGA). RESULTS A positive correlation was found between hormonal level and gestational age. This work allowed us to define a threshold for preterm newborn according to their gestational age. CONCLUSION Owing to lack of consensus, those values are useful for clinical and biological follow-up of thyroid function for newborns at risk (SGA and preterm before 32 weeks) during the first year of life. Finally, it would be interesting to study systematic supplementation of thyroid hormone for those infants in a prospective study.
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Affiliation(s)
- A Cartault Grandmottet
- Unité d'endocrinologie, pathologie osseuse, gynécologie et génétique, hôpital des Enfants, CHU de Toulouse, TSA 70034, 31059 Toulouse, France.
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Osborn DA, Hunt RW. Prophylactic postnatal thyroid hormones for prevention of morbidity and mortality in preterm infants. Cochrane Database Syst Rev 2007; 2007:CD005948. [PMID: 17253571 PMCID: PMC9004229 DOI: 10.1002/14651858.cd005948.pub2] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Observational studies have shown an association between transiently low thyroid hormone levels in preterm infants in the first weeks of life (transient hypothyroxinaemia) and abnormal neurodevelopmental outcome. Thyroid hormone replacement might prevent this. OBJECTIVES To determine whether prophylactic thyroid hormones given to preterm infants without congenital hypothyroidism result in clinically important changes in neonatal and long term outcomes. SEARCH STRATEGY The standard search strategy of the Neonatal Review Group was used. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2006), MEDLINE (1966 - March 2006), EMBASE, PREMEDLINE, and searches of abstracts of conference proceedings, citations of published articles and expert informants. SELECTION CRITERIA All trials using random or quasi-random patient allocation in which prophylactic thyroid hormone treatment was compared to control in premature infants. DATA COLLECTION AND ANALYSIS Assessment of trial quality, data extraction and synthesis of data, using relative risk (RR) and weighted mean difference (WMD), were performed using standard methods of the Cochrane Collaboration and its Neonatal Review Group. MAIN RESULTS Four studies enrolling 318 infants were included. All studies enrolled preterm infants on the basis of gestational age criteria. All studies commenced treatment in the first 48 hours, but used different regimens, dose and durations of treatment. All four studies used thyroxine (T4). Valerio 2004 incorporated one arm with an early short course of T3, then T4 for 6 weeks. Only two studies with neurodevelopmental follow-up were of good methodology (van Wassenaer 1997; Vanhole 1997). All studies were small with the largest (van Wassenaer 1997) enrolling 200 infants.No significant difference was found in neonatal morbidity, mortality or neurodevelopmental outcome in infants who received thyroid hormones compared to control. van Wassenaer 1997 reported no significant difference in abnormal mental development at 6, 12, 24 months (RR 0.67, 95% CI 0.28, 1.56) or five years (RR 0.66, 95% CI 0.22, 1.99) or cerebral palsy assessed at five years (RR 0.72, 95% CI 0.28, 1.84). Meta-analysis of two studies (van Wassenaer 1997, Vanhole 1997) found no significant difference in the Bayley MDI (WMD -1.14, 95% CI -5.46, 3.19) and PDI (WMD 0.22, 95% CI -4.80, 5.24) at 7 - 12 months. van Wassenaer 1997 reported no significant difference in the Bayley MDI (MD -3.50, 95% CI -11.21, 4.21) and PDI (MD 3.10, 95% CI -3.31, 9.51) at 24 months, IQ scores at 5 years (MD -2.10, 95% CI -7.91, 3.71) and children in special schooling at 10 years (RR 0.88, 95% CI 0.43, 1.83). Meta-analysis of all four trials found no significant difference in mortality to discharge (typical RR 0.76, 95% CI 0.46 to 1.24). van Wassenaer 1997 reported no significant difference in death or cerebral palsy at five years (RR 0.70, 95% CI 0.43 to 1.14). No significant differences were reported for neonatal morbidities, including the need for mechanical ventilation, duration of mechanical ventilation, air leak, CLD in survivors at 28 days or 36 weeks, intraventricular haemorrhage, severe intraventricular haemorrhage, periventricular leucomalacia, patent ductus arteriosus, sepsis, necrotising enterocolitis or retinopathy of prematurity. AUTHORS' CONCLUSIONS This review does not support the use of prophylactic thyroid hormones in preterm infants to reduce neonatal mortality, neonatal morbidity or improve neurodevelopmental outcomes. An adequately powered clinical trial of thyroid hormone supplementation with the goal of preventing the postnatal nadir of thyroid hormone levels seen in very preterm infants is required.
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Affiliation(s)
- D A Osborn
- Royal Prince Alfred Hospital, RPA Newborn Care, Missenden Road, Camperdown, New South Wales, Australia, 2050.
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Abstract
BACKGROUND Extremely premature infants are at risk of transient hypothyroxinaemia in the first weeks after birth. These low thyroid hormone levels are associated with an increased incidence of neonatal morbidity, mortality and longer term developmental impairments. Thyroid hormone therapy might prevent these problems. OBJECTIVES To determine the evidence for thyroid hormone therapy in preterm infants with transient hypothyroxinaemia (low thyroid hormone level, normal TSH) for improvement of neonatal outcomes and neurodevelopment. SEARCH STRATEGY Searches were performed of The Cochrane Central Register of Controlled (CENTRAL, The Cochrane Library, Issue 1, 2006), MEDLINE (1966 - March 2006), PREMEDLINE (March 2006), EMBASE (1980 - March 2006), previous reviews including cross references, abstracts and conference proceedings, supplemented by requests to expert informants. SELECTION CRITERIA Trials enrolling preterm infants with transient hypothyroxinaemia (low thyroid hormone level, normal TSH level) in the neonatal period, using random or quasi-random patient allocation to thyroid hormone therapy compared to control (placebo or no treatment). DATA COLLECTION AND ANALYSIS Independent assessment of trial quality and data extraction by each review author. Synthesis of data using relative risk (RR) and weighted mean difference (WMD) using standard methods of the Cochrane Collaboration and its Neonatal Review Group. MAIN RESULTS Only one study was eligible. Chowdhry (1984) enrolled 23 infants < 1250 g and 25 - 28 weeks gestation with transient hypothyroxinaemia (serum total T4 </=4 mug/dl and TSH </= 20 IU/L). Infants were randomised to thyroxine 10 mug/kg/day or placebo beginning on day 15 and continuing daily for seven weeks. Chowdhry (1984) reported no neonatal mortality and one infant death in each group prior to discharge. No significant difference was reported in CLD at 28 days or 36 weeks, patent ductus arteriosus, necrotising enterocolitis, retinopathy or prematurity, weight gain, growth in head circumference or length. No significant difference was reported for mean T4 levels between thyroxine and placebo treated infants on day 21, 35, 49, 63 and 77 after birth. Free T4 was not measured. Neurodevelopmental follow up was inadequate to draw any conclusions from. AUTHORS' CONCLUSIONS There is insufficient evidence to determine whether use of thyroid hormones for treatment of preterm infants with transient hypothyroxinaemia results in changes in neonatal morbidity and mortality, or reductions in neurodevelopmental impairments. Further research is required.
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Affiliation(s)
- D A Osborn
- Royal Prince Alfred Hospital, RPA Newborn Care, Missenden Road, Camperdown, New South Wales, Australia, 2050.
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Affiliation(s)
- C I Lanting
- Department of Obstetrics/Paediatrics, University of Groningen, The Netherlands
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Abstract
Thyroid hormones are required for normal development of the brain. Transient hypothyroxinaemia is the most common thyroid dysfunction in preterm infants and is defined by temporary low levels of T4, T3 and normal or low TSH. Low T4 levels in preterm infants are associated with persistent neurodevelopmental deficits in cognitive and motor function. Thyroid hormone substitution trials to date are underpowered and show inconsistent results; the question remains -- are low T4 levels simply an epiphenomenon? The aetiology of transient hypothyroxinaemia is multifactorial and the components amenable to correction form the basis of the therapeutic strategy: rectification of iodine deficiency in parenteral nutrition; a reduction of non-thyroidal illnesses and attenuation of their severity; and substitution of drugs that interfere with the hypothalamic-pituitary-thyroid axis. Thyroxine substitution therapy should only be done in the context of clinical trials and only in those infants who are hypothyroxinaemic.
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Ng SM, Wong SC, Paize F, Chakkarapani E, Newland P, Isherwood DM, Didi M. Delay in screening premature infants for congenital hypothyroidism. Arch Dis Child Fetal Neonatal Ed 2006; 91:F465-6. [PMID: 17056851 PMCID: PMC2672776 DOI: 10.1136/adc.2005.091264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Abstract
An opportunity to determine the cause of death, factors that may have a role in it, and the extent and cause of malformations is provided by perinatal autopsy. The family may be assisted in finding closure after the death of their infant by the information obtained. Insight into classifying infants appearing normal into one of three groups, small, appropriate and large for gestational age, has been provided, as each group tends to have specific causes of death. In infants with congenital anomalies, patterns of malformation may lead us to the diagnosis. An accurate diagnosis is required to provide counselling for a subsequent pregnancy.
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Osborn DA, Hunt RW. Prophylactic postnatal thyroid hormones for prevention of morbidity and mortality in preterm infants. THE COCHRANE DATABASE OF SYSTEMATIC REVIEWS 2006. [DOI: 10.1002/14651858.cd005948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ibrahim M, Sinn J, McGuire W. Iodine supplementation for the prevention of mortality and adverse neurodevelopmental outcomes in preterm infants. Cochrane Database Syst Rev 2006:CD005253. [PMID: 16625632 DOI: 10.1002/14651858.cd005253.pub2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Parenteral nutrition solutions, formula milks, and human breast milk contain insufficient iodine to meet recommended intakes for preterm infants. Iodine deficiency may exacerbate transient hypothyroxinaemia in preterm infants and this may be associated with adverse respiratory or neurological outcomes. OBJECTIVES To assess the evidence from randomised controlled trials that dietary supplementation with iodine reduces mortality and morbidity in preterm infants. SEARCH STRATEGY We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2005), MEDLINE (1966 - November 2005), EMBASE (1980 - November 2005), CINAHL (1982 - November 2005), conference proceedings, and previous reviews. SELECTION CRITERIA Randomised or quasi-randomised controlled trials that compared a policy of supplementing enteral or parenteral feeds with iodine (more than 30 micrograms per kilogram per day) versus placebo or no supplementation in preterm infants. DATA COLLECTION AND ANALYSIS The standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two reviewers, and synthesis of data using relative risk, risk difference and weighted mean difference. The primary outcomes for this review were neonatal mortality, death before hospital discharge, and longer term neurodevelopmental outcomes including severe neurodevelopmental disability. MAIN RESULTS We found only one randomised controlled trial (N = 121) that fulfilled the review eligibility criteria (Rogahn 2000). The participants were infants born before 33 weeks' gestation (but most were of birth weight greater than 1000 grams). The primary aim of this trial was to assess the effect of iodine supplementation on thyroid function. The investigators did not detect any statistically significant effects on the plasma levels of thyroxine (free and total), triiodothyronine, or thyrotrophin in preterm infants (measured up to 40 weeks' post-conceptional age). Only one infant died and the trial was therefore underpowered to detect an effect on mortality. The trial did not assess the effect of the intervention on neurodevelopmental morbidity. There was not a statistically significant difference in the incidence of chronic lung disease. AUTHORS' CONCLUSIONS There are insufficient data at present to determine whether providing preterm infants with supplemental iodine (to match fetal accretion rates) prevents morbidity and mortality in preterm infants. Future randomised controlled trials of iodine supplementation should focus on extremely preterm and extremely low birth weight infants, the group at greatest risk of transient hypothyroxinaemia. These trials should aim to assess the effect of iodine supplementation on clinically important outcomes including respiratory morbidity and longer term neurodevelopment.
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Affiliation(s)
- M Ibrahim
- Victoria Hospital, Department of Paediatrics, Hayfield Road, Kirkcaldy, Fife, UK, KY2 5AH.
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La Gamma EF, van Wassenaer AG, Golombek SG, Morreale de Escobar G, Kok JH, Quero J, Ares S, Paneth N, Fisher D. Neonatal Thyroxine Supplementation for Transient Hypothyroxinemia of Prematurity. ACTA ACUST UNITED AC 2006; 5:335-46. [PMID: 17107219 DOI: 10.2165/00024677-200605060-00002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Extremely low birth-weight newborns (<1000g) experience low levels of thyroid hormone that vary inversely with the severity of neonatal illness and the extent of developmental immaturity with levels reaching a nadir at approximate, equals7 days after birth; this phenomenon can persist for several weeks. In the absence of transplacental passage, 30-50% of these neonates cannot generate sufficient quantities of thyroid hormone to meet postnatal demands, placing them at an increased risk for developmental delay and cerebral palsy. Population surveys and interventional trials suggest that a therapeutic opening exists during a 'window of opportunity' corresponding to this period of diminished capacity. Variables to consider before intervention focus on the consideration that supplementation of both the substrate thyroxine and the active hormone triiodothyronine may be necessary in quantities that do not suppress thyroid-stimulating hormone release, yet overcome the persistence of increased conversion to 3,3'5'-triodo-L-thyronine, terminal deiodination, and activity of the sulfation inactivation pathways, as well as the diminished capacity of the newborn to accommodate postnatal physiologic changes. Single daily replacement doses may suppress levels of converting enzymes in the brain, suggesting that physiologic 'mimicry' provided by a constant infusion may be the preferred dosing option. Properly powered clinical trials targeting long-term developmental outcomes are needed to discern whether these interventions will do more than simply elevate blood levels of thyroid hormones to the target values of either the fetus or developing neonate. Identifying the appropriate indications for supplementation may alleviate individual pain and distress due to disability for several hundred extremely low birth-weight neonates each year in the US alone, and save society a pro-rated lifetime cost of nearly $US1 million per child.
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Affiliation(s)
- Edmund F La Gamma
- The Regional Neonatal Center, Maria Fareri Children’s Hospital at Westchester Medical Center, New York Medical College, Valhalla, New York, USA
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Abstract
Iodine is a trace element which is essential for the synthesis of thyroid hormones. The thyroid hormones, thyroxine (T4) and 3,5,3'-triiodothyronine (T3), are necessary for adequate growth and development throughout fetal and extrauterine life. The iodine intake of newborns is entirely dependent on the iodine content of breast milk and the formula preparations used to feed them. An inadequate iodine supply might be especially dangerous in the case of premature babies. The minimum recommended dietary allowance (RDA) for different age groups has recently been revised. The iodine intake required is at least 15 microg/kg/day in full-term infants and 30 microg/kg/day in preterms. The iodine content of many evaluated preparations for feeding premature infants appears to be inadequate. Premature infants are now in a situation of iodine deficiency, precisely at a stage of psychomotor and neural development which is extremely sensitive to alterations of thyroid function.
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Affiliation(s)
- Susana Ares
- Neonatology Unit, University Hospital La Paz, Paseo de la Castellana 261, 28046 Madrid, Spain
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van Wassenaer AG, Westera J, Houtzager BA, Kok JH. Ten-year follow-up of children born at <30 weeks' gestational age supplemented with thyroxine in the neonatal period in a randomized, controlled trial. Pediatrics 2005; 116:e613-8. [PMID: 16234230 DOI: 10.1542/peds.2005-0876] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Thyroid hormones are essential for brain development. We conducted a randomized, controlled trial with thyroxine (T4) supplementation in infants <30 weeks' gestation and with the last neurodevelopmental follow-up moment at the age of 5.5 years. T4 supplementation was associated with improved outcome of infants <28 weeks' gestation and worse outcome of infants of 29 weeks' gestation. We studied gestational age-dependent effects of T4 supplementation at the mean age of 10.5 years in children participating in our randomized, controlled trial. METHODS Questionnaires regarding school outcome, behavior, quality of life, motor problems, and parental stress were sent to the parents and children and their teachers at the same time point for all surviving children (9-12 years of age). RESULTS Seventy-two percent of the families responded to our questionnaires. Nonrespondents had more sociodemographic risk factors and worse development until 5.5 years. At the mean age of 10.5 years, T4 supplementation was associated with better school outcome in those who were <27 weeks' gestation and better motor outcome in those who were <28 weeks' gestation, whereas the reverse was true for those who were born at 29 weeks' gestation. No other gestational age-dependent outcomes were found. CONCLUSIONS Gestation-dependent effects of T4 supplementation remain stable over time. These effects do not prove beneficial effects of T4 in infants <28 weeks but should be the background for a new randomized, controlled trial with thyroid hormone in this age group.
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Affiliation(s)
- Aleid G van Wassenaer
- Department of Neonatology, Emma Children's Hospital Academic Medical Center, Amsterdam, The Netherlands.
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Martin CR, Van Marter LJ, Allred EN, Leviton A. Antenatal Glucocorticoids Increase Early Total Thyroxine Levels in Premature Infants. Neonatology 2005; 87:273-80. [PMID: 15703468 DOI: 10.1159/000083876] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Accepted: 11/30/2004] [Indexed: 11/19/2022]
Abstract
BACKGROUND Hypothyroxinemia is associated with adverse neonatal outcomes including white matter damage, cerebral palsy, poor neurodevelopment and death. It has become increasingly important to understand the natural history and modifiers of thyroid function in the premature infant. It is standard obstetrical practice to offer antenatal glucocorticoids to pregnant women with threatened preterm delivery. Few studies have investigated the effect of antenatal glucocorticoids on neonatal thyroid function. OBJECTIVE To examine the association between antenatal exposure to glucocorticoids and early total thyroxine (T4) levels among extremely premature infants. METHODS We studied 521 infants born at 4 medical centers. Entry criteria included a gestational age of 23-28 weeks and a serum thyroxine level obtained in the first postnatal week. Receipt of antenatal glucocorticoids was recorded as none, partial, or complete. A complete course consisted of two doses of betamethasone or four doses of dexamethasone within a 48-hour period between 2 and 7 days of delivery. Early total T4 levels were obtained from state-mandated newborn screening programs. RESULTS Controlling for potential maternal, perinatal and neonatal confounding variables, infants exposed to a complete course of antenatal glucocorticoids had total T4 levels 0.8 microg/dl higher than their peers who were not exposed to a complete course of antenatal glucocorticoids (p = 0.03). CONCLUSIONS Extremely premature infants who received a complete course of antenatal glucocorticoids had significantly higher total thyroxine levels in the first postnatal week. Maternal, perinatal, and early neonatal variables did not completely explain this association. We speculate that antenatal glucocorticoids influence early neonatal thyroid function.
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Affiliation(s)
- Camilia R Martin
- Department of Neonatology, Beth Israel Deaconess Medical Center, Division of Newborn Medicine, Boston, MA 02215, USA.
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Mirabella G, Westall CA, Asztalos E, Perlman K, Koren G, Rovet J. Development of contrast sensitivity in infants with prenatal and neonatal thyroid hormone insufficiencies. Pediatr Res 2005; 57:902-7. [PMID: 15774837 DOI: 10.1203/01.pdr.0000157681.38042.b4] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Thyroid hormone is essential for normal brain development including structures critical for visual processing. While chick and rodent models have demonstrated abnormal visual development following prenatal thyroid hormone loss, comparable data do not exist in the human. To determine whether human infants with intrauterine and early postnatal thyroid hormone insufficiencies have compromised visual abilities, we investigated contrast sensitivity and visual acuity development in 13 infant offspring of women with hypothyroidism during pregnancy (HYPO), 16 preterm infants born between 32 and 35 weeks gestation, 12 infants with congenital hypothyroidism (CH), and 20 typically developing infants. All were assessed with the sweep visual evoked potential technique at 3, 4.5, and 6 months (corrected) age. Results showed significantly reduced contrast sensitivity but normal visual acuity in HYPO and CH groups relative to controls (p < 0.003 and p < 0.05 respectively). Stratification of the HYPO group into subgroups based on maternal TSH levels during the first half of pregnancy revealed lower contrast sensitivities for infants whose mothers' TSH values were above than below the median (p < 0.05). In the CH group, those with an absent thyroid gland and/or a newborn TSH value above 200 mIU/L had lower contrast sensitivities than did those with other etiologies or TSH levels below 100 mIU/L (p < 0.05). There were no significant effects involving the preterm group. These results indicate that thyroid hormone is important for human visual development.
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Affiliation(s)
- Giuseppe Mirabella
- Department of Ophthalmology and Vision Science, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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Hume R, Simpson J, Delahunty C, van Toor H, Wu SY, Williams FLR, Visser TJ. Human fetal and cord serum thyroid hormones: developmental trends and interrelationships. J Clin Endocrinol Metab 2004; 89:4097-103. [PMID: 15292353 DOI: 10.1210/jc.2004-0573] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Thyroid hormone is essential for fetal and neonatal development in particular of the brain, but little is known about regulation of fetal thyroid hormone levels throughout human gestation. The purpose of this study was to clarify developmental trends and interrelationships among T(4), free T(4) (FT4), thyroxine-binding globulin (TBG), TSH, T(3), rT(3), and T(4) sulfate (T4S) levels in cord and fetal blood sera (n = 639, 15-42 wk gestation) and correlate infant levels (23-42 wk gestation) to maternal values (n = 428, 16-45 yr) and those of nonpregnant women (n = 233, 16-46 yr). In cord and fetal serum, T(4), T(3), and TBG levels increase with gestation until term; TSH, FT4, T4S, and rT(3) levels increase and peak in the late second/early third trimester and then decline to term; T(4)/TBG ratios increase until late second trimester and plateau to term. Term cord sera TSH, TBG, and all iodothyronine levels, except T(3), are higher than nonpregnant women. In the third trimester, cord serum FT4, TSH, rT(3), and T4S levels are also higher than corresponding maternal levels, but T(4), T(3), and TBG levels are lower than maternal values. The late second/early third trimester is a critical transition period in fetal thyroid hormone metabolism, which may be interrupted by preterm birth and contribute to postnatal thyroid dysfunction.
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Affiliation(s)
- Robert Hume
- Maternal and Child Health Sciences, University of Dundee, Ninewells Hospital, and Medical School, Dundee DD1 9SY, Scotland, United Kingdom.
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