Divergence of Iodine and Thyroid Hormones in the Fetal and Maternal Parts of Human-Term Placenta

Peng, Siyun; Li, Chenyan; Xie, Xiaochen; Zhang, Xiaomei; Wang, Danyang; Lu, Xixuan; Sun, Manni; Meng, Ting; Wang, Shiwei; Jiang, Yaqiu; Shan, Zhongyan; Wang, Teng

doi:10.1007/s12011-019-01834-z

Cited by 16 publications

(28 citation statements)

References 51 publications

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“…It must be noted that the majority of these pregnant Irish women was iodine deficient, as evaluated by the UIC. In contrast, reported levels of iodine in placentas from mother-neonate pairs of the Liaoning Province in northeastern China (a known iodine sufficient region) were 10 to 20 times higher than those from our study 28 . In that study, iodine concentrations were measured by ICP-MS after acid mineralization (HNO 3 + H 2 O 2 ) in a microwave oven.…”

Section: Intra-versus Interplacental Differences In Iodine Concentratcontrasting

confidence: 99%

“…The method described in the present study (based on TMAH extraction, followed by ICP-MS measurement) has some advantages over the previously described Sandell-Kolthoff reaction 1 , or the acidic extraction of iodine, followed by ICP-MS 28 . First, in comparison with the method proposed by Burns et al 1 , the sample preparation time is shorter and more energy efficient: we digested samples for 3 hours at 90 °C in a TMAH solution, compared to overnight drying and subsequent incineration for 3 hours at 600 °C.…”

Section: Methods Performance Characteristics Limit Of Detection (Lod)mentioning

confidence: 95%

“…Due to the risk for formation of volatile compounds such as HI or I 2 , iodine losses may occur 26 . Unfortunately, neither that recent study 28 , nor the study by Burns and colleagues 1 provide information on the performance characteristics of the method they used, which does not permit a sound evaluation of the accuracy of their methods.…”

Section: Methods Performance Characteristics Limit Of Detection (Lod)mentioning

confidence: 99%

“…Some uncertainty remains regarding the suitability of acid mineralizations (with HNO 3 ) as a sample preparation method for placental tissues prior to iodine measurements with ICP-MS as performed by Peng and colleagues 28 . Due to the risk for formation of volatile compounds such as HI or I 2 , iodine losses may occur 26 .…”

Section: Methods Performance Characteristics Limit Of Detection (Lod)mentioning

confidence: 99%

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Variability of iodine concentrations in the human placenta

Neven

Marien

Janssen

et al. 2020

Sci Rep

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iodine is an essential trace element, necessary for the production of thyroid hormones, which play a key role in optimal foetal growth and (neuro-) development. To date, iodine deficiency remains a health burden in many countries. We investigated the variability of placental iodine concentrations within and between individuals. We used 20 mother-neonate pairs from the ENVIRONAGe birth cohort, took samples at three standardized locations of the placentas, pooled and digested them, and determined the iodine concentrations using an ICP-MS method as an alternative for the Sandell-Kolthoff method. the variability between and within the three sample regions was calculated using the intra-class correlation coefficient (ICC) from the variance components of mixed models. With the Friedman test, the differences between placental biopsies were assessed. The ICC showed a higher between-placenta (68.6%) than within-placenta (31.4%) variability. Subsequently, we used our optimized method to determine iodine concentrations in 498 mother-neonate pairs, which averaged 26.1 μg/kg. For 96 mothers, the urinary iodine concentrations were also determined, which showed no correlation with the placental iodine storage, as was expected. Future studies are necessary to explore the effects of these placental iodine concentrations in relation to health outcomes of mother and child at birth and later in life.During gestation, the placenta acts as an important gatekeeper between the foetal and the maternal environment. This crucial organ is able to prevent harmful substances from reaching the foetus and allows nutrients, like iodine, to be transported from mother to child. This trace element plays a vital role in the production and regulation of thyroid stimulating hormone (TSH) and the thyroid hormones tri-iodothyronine (T3) and thyroxine (T4), which are essential for optimal foetal growth and (neuro)development 1 . These thyroid hormones are produced by the maternal thyroid gland, bind to plasma proteins for transportation throughout the body, cross the placenta and subsequently reach the foetus 2 . Both hormones play an essential role in the foetal neurogenesis, as well as normal development and differentiation of numerous cell types throughout the body 3 . Both inadequate or excess amounts of iodine can lead to a decrease in the thyroid hormone levels in both mother and foetus, which could impair the neurocognitive development 4 . In the first trimester of pregnancy, the foetus is unable to produce these hormones itself, and relies entirely on the maternal thyroid hormone stores 5,6 . In the later stages of pregnancy, the role of the mother is to maintain an adequate iodine supply to the foetal thyroid gland 7 .The diet is the most important source of iodine for humans. According to the World Health Organization (WHO), the recommended daily iodine intake for the pregnant and lactating population should range between 150 to 249 μg per day to ensure iodine sufficiency 8 . While numerous iodine supplementation programmes have been implemente...

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Section: Intra-versus Interplacental Differences In Iodine Concentratcontrasting

confidence: 99%

Section: Methods Performance Characteristics Limit Of Detection (Lod)mentioning

confidence: 95%

Section: Methods Performance Characteristics Limit Of Detection (Lod)mentioning

confidence: 99%

Section: Methods Performance Characteristics Limit Of Detection (Lod)mentioning

confidence: 99%

See 2 more Smart Citations

Variability of iodine concentrations in the human placenta

Neven

Marien

Janssen

et al. 2020

Sci Rep

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show abstract

“…A recent study by Peng et al. ( 23 ), examines the divergence of iodine and thyroid hormones in a term placenta. Placenta is the only other organ, other than the thyroid gland, that stores iodine.…”

Section: Section 01 – Regulation and Feedback Loopsmentioning

confidence: 99%

Understanding the Pathogenesis of Gestational Hypothyroidism

Kankanamalage

Zhou

2021

Front. Endocrinol.

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Pregnancy is a complex state with many endocrinological challenges to a woman’s physiology. Gestational Hypothyroidism (GHT) is an emerging condition where insufficiency of the thyroid gland has developed during pregnancy in a previously euthyroid woman. It is different to overt hypothyroidism, where marked elevation of thyroid-stimulating hormone with corresponding reduction in free thyroxine levels, is well known to cause detrimental effects to both the mother and the baby. During the past couple of decades, it has been shown that GHT is associated with multiple adverse maternal and fetal outcomes such as miscarriage, pre-eclampsia, placental abruption, fetal loss, premature delivery, neurocognitive and neurobehavioral development. However, three randomized controlled trials and a prospective cohort study performed within the last decade, show that there is no neurodevelopmental improvement in the offspring of mothers who received levothyroxine treatment for GHT. Thus, the benefit of initiating treatment for GHT is highly debated within the clinical community as there may also be risks associated with over-treatment. In addition, regulatory mechanisms that could possibly lead to GHT during pregnancy are not well elucidated. This review aims to unravel pregnancy induced physiological challenges that could provide basis for the development of GHT. During pregnancy, there is increased renal clearance of iodine leading to low iodine state. Also, an elevated estrogen level leading to an increase in circulating thyroglobulin level and a decrease in free thyroxine level. Moreover, placenta secretes compounds such as human chorionic gonadotropin (hCG), placental growth factor (PIGF) and soluble FMS-like tyrosine kinase-1 (s-Flt1) that could affect the thyroid function. In turn, the passage of thyroid hormones and iodine to the fetus is highly regulated within the placental barrier. Together, these mechanisms are hypothesized to contribute to the development of intolerance of thyroid function leading to GHT in a vulnerable individual.

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Thyroid hormones: Metabolism and transportation in the fetoplacental unit

Zuñiga

Muñoz

Pustovrh

2022

Molecular Reproduction Devel

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The thyroid hormones (THs), thyroxine (T4) and triiodothyronine (T3), are of vital importance for fetal development. The concentration of THs in fetal circulation varies throughout gestation and differs from the concentration in the maternal serum, indicating the presence of maternal‐fetal thyroid homeostasis regulatory mechanisms in the placenta. The passage of THs from maternal circulation to fetal circulation is modulated by plasma membrane transporters, enzymes, and carrier proteins. Monocarboxylate transporter 8, iodothyronine deiodinases (DIO2 and DIO3), and transthyretin are especially involved in this maternal‐fetal thyroid modulation, shown by a greater expression in the placenta. THs also play a role in placental development and as expected, abnormal variations in TH levels are associated with pregnancy complications and can result in damage to the fetus. Although new evidence regarding TH regulation during pregnancy and its effects in the mother, placenta, and fetus has been published, many aspects of these interactions are still poorly understood. The objective of this review is to provide an evidence‐based update, drawn from current data, on the metabolism and transport of THs in the placenta and their vital role in the maternal‐fetal relationship.

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Divergence of Iodine and Thyroid Hormones in the Fetal and Maternal Parts of Human-Term Placenta

Cited by 16 publications

References 51 publications

Variability of iodine concentrations in the human placenta

Variability of iodine concentrations in the human placenta

Understanding the Pathogenesis of Gestational Hypothyroidism

Thyroid hormones: Metabolism and transportation in the fetoplacental unit

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