Treatment of thyroid disorders before conception and in early pregnancy: a systematic review

Vissenberg, Rosa; Boogaard, E. van den; Wely, Madelon van; Post, Joris A. M. van der; Fliers, Eric; Bisschop, Peter H.; Goddijn, Mariëtte

doi:10.1093/humupd/dms007

Cited by 119 publications

(77 citation statements)

References 42 publications

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“…The fact that total MMI levels are similar could be an element in favour of the first hypothesis. The major problem with MMI as well as other thionamides in humans and more precisely in pregnant women is that these compounds are transferred to the developing foetus via the placenta and may harm normal development (Cooper 2005, Vissenberg et al 2012. In birds, essential as well as potentially harmful substances are deposited in the egg and taken up by the embryo during development.…”

Section: Discussionmentioning

confidence: 99%

“…However, these drugs may in turn have a negative impact on foetal development as they can cross the placenta. The present clinical guidelines advise to avoid the use of MMI in early pregnancy because it may increase the risk of specific malformations including choanal and oesophageal atresia and aplasia cutis congenita (Wolf et al 2006, Azizi & Amouzegar 2011, Rodriguez-Garcia et al 2011, Vissenberg et al 2012, but it remains unclear whether these abnormalities are linked to MMI or to the maternal hyperthyroidism itself (Barbero et al 2008).…”

Section: Introductionmentioning

confidence: 99%

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Maternal transfer of methimazole and effects on thyroid hormone availability in embryonic tissues

Herck

Geysens²,

Bald³

et al. 2013

Journal of Endocrinology

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Methimazole (MMI) is an anti-thyroid drug used in the treatment of chronic hyperthyroidism. There is, however, some debate about its use during pregnancy as MMI is known to cross the mammalian placenta and reach the developing foetus. A similar problem occurs in birds, where MMI is deposited in the egg and taken up by the developing embryo. To investigate whether maternally derived MMI can have detrimental effects on embryonic development, we treated laying hens with MMI (0.03% in drinking water) and measured total and reduced MMI contents in the tissues of hens and embryos at different stages of development. In hens, MMI was selectively increased in the thyroid gland, while its levels in the liver and especially brain remained relatively low. Long-term MMI treatment induced a pronounced goitre with a decrease in thyroxine (T 4 ) content but an increase in thyroidal 3,5,3 0 -triiodothyronine (T 3 ) content. This resulted in normal T 3 levels in tissues except in the brain. In chicken embryos, MMI levels were similar in the liver and brain. They gradually decreased during development but always remained above those in the corresponding maternal tissues. Contrary to the situation in hens, T 4 availability was only moderately affected in embryos. Peripheral T 3 levels were reduced in 14-day-old embryos but normal in 18-day-old embryos, while brain T 3 content was decreased at all embryonic stages tested. We conclude that all embryonic tissues are exposed to relatively high doses of MMI and its oxidised metabolites. The effect of maternal MMI treatment on embryonic thyroid hormone availability is most pronounced for brain T 3 content, which is reduced throughout the embryonic development period.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Maternal transfer of methimazole and effects on thyroid hormone availability in embryonic tissues

Herck

Geysens²,

Bald³

et al. 2013

Journal of Endocrinology

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“…Although the benefits of Chypo treatment with T 4 are without doubt reported (9,131), in the case of SChypo, no conclusive work has yet appeared as noted in a recent Cochrane review (132). This review concluded that there is insufficient data supporting the treatment of SChypo, and therefore it is difficult to justify the implementation of a universal screening program to detect TD in the pregnant population.…”

Section: Treatment Of Pregnant Women With Td Is Safe and Cheapmentioning

confidence: 98%

CONTROVERSIES IN ENDOCRINOLOGY: On the need for universal thyroid screening in pregnant women

Vila

Velasco

González

et al. 2014

European Journal of Endocrinology

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There is a well-known controversy among scientific societies regarding the recommendation to screen for thyroid dysfunction (TD) during pregnancy. Although several studies have shown an association between maternal subclinical hypothyroidism and/or hypothyroxinemia with obstetric problems and/or neurocognitive impairment in the offspring, there is only limited evidence on the possible positive effects of thyroxine (T 4 ) treatment in such cases. Despite the scarcity of this evidence, there is a widespread agreement among clinicians on the need for treatment of clinical hypothyroidism during pregnancy and the risks that could arise due to therapeutic abstention. As maternal TD is a quite prevalent condition, easily diagnosed and for which an effective and safe treatment is available, some scientific societies have proposed to assess thyroid function during the first trimester of pregnancy and ideally before week 10 of gestational age. Given the physiologic changes of thyroid function during pregnancy, hormone assessment should be performed using trimester-specific reference values ideally based on locally generated data as geographic variations have been detected. Screening of TD should be based on an initial determination of TSH performed early during the first trimester and only if abnormal should it be followed by either a free or total T 4 measurement. Furthermore, adequate iodine supplementation during pregnancy is critical and if feasible it should be initiated before the woman attempts to conceive.

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“…36 Even though ESHRE and RCOG have no definite recommendations for treating SCH, ESCP suggests treating SCH due to potential benefits of therapy. 37 Feto-maternal effects of hypothyroidism such as abortus during pregnancy and mental retardation was clearly established. 38 Additionally, in recent times association of SCH with unwanted antenatal complications such as premature birth, placental detachment and intrauterine deaths was demonstrated.…”

Section: Subclinical Hypothyroidismmentioning

confidence: 99%

Thyroid disorders and fertility

Karaca

Akpak

2015

Int J Res Med Sci

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Treatment of thyroid disorders before conception and in early pregnancy: a systematic review

Cited by 119 publications

References 42 publications

Maternal transfer of methimazole and effects on thyroid hormone availability in embryonic tissues

Maternal transfer of methimazole and effects on thyroid hormone availability in embryonic tissues

CONTROVERSIES IN ENDOCRINOLOGY: On the need for universal thyroid screening in pregnant women

Thyroid disorders and fertility

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