Current knowledge about the in utero and peripartum management of fetal goiter associated with maternal Graves' disease

Recommendations of the AGG (Working Group for Obstetrics, Department of Maternal Diseases) on How to Treat Thyroid Function Disorders in Pregnancy

Objective These recommendations from the AGG (Committee for Obstetrics, Department of Maternal Diseases) on how to treat thyroid function disorder during pregnancy aim to improve the diagnosis and management of thyroid anomalies during pregnancy.

Methods Based on the current literature, the task force members have developed the following recommendations and statements. These recommendations were adopted after a consensus by the members of the working group.

Recommendations The following manuscript gives an insight into physiological and pathophysiological thyroid changes during pregnancy, recommendations for clinical and subclinical hypo- and hyperthyroidism, as well as fetal and neonatal diagnostic and management strategies.

Immediate postnatal central hypothyroidism caused by maternal Graves' disease: Importance of early screening

This report illustrates a case of central hypothyroidism in a newborn immediately after birth caused by maternal Graves' disease. Infants from mothers with Graves' disease require careful examination without waiting for neonatal screening results, even though the mother's thyroid function is normal at birth or the newborn does not have goiter.

A Novel Mutation in the Thyroglobulin Gene Resulting in Neonatal Goiter and Congenital Hypothyroidism in an Eritrean Infant

Congenital hypothyroidism (CH) due to dyshormonogenesis may occur due to mutations in any of the key genes involved in thyroid hormone biosynthesis (TG, TPO, DUOX2, DUOXA2, SLC5A5, IYD, SLC26A4 and SLC26A7). Mutations in the thyroglobulin gene (TG) are frequently associated with goiter, which may present fetally or neonatally, although a spectrum of phenotypes is reported. We present the case of a woman of Eritrean origin who presented in the third trimester of pregnancy in the early stages of labor. Ultrasound at presentation revealed a fetal neck swelling consistent with a goiter. Following delivery by Caesarian section with minimal respiratory support, the infant was found to be hypothyroid with undetectable serum levels of thyroglobulin. Sequencing of the TG revealed a homozygous donor splice site pathogenic variant (c.5686+1delG) not previously described in the literature. Levothyroxine treatment resulted in normal growth and psychomotor development. Goitrous CH with inappropriately low thyroglobulin has previously been reported in patients harbouring homozygous single nucleotide substitutions at the same TG donor splice site, which result in exon skipping and retention of malformed thyroglobulin by the endoplasmic reticulum. We conclude that the TG c.5686+1delG pathogenic variant is the likely basis for our patient’s fetal goiter and CH, and that the clinical phenotype associated with TG c.5686+1delG is comparable to that seen with single nucleotide substitutions at the same site.

Taking the Natural Exit: Opportunities for Treatment Rightsizing in Fetal Head and Neck Mass

Fetal head and neck masses, when present, may cause neonatal airway obstruction at birth and associated morbidity and mortality. Escalated maternal treatment intensity such as surgical laryngoscopist/airway surgeon attended delivery and ex utero intrapartum treatment can mitigate the neonatal risk, however, increase maternal risk for complications. Accordingly, accurate prediction of the potential neonatal benefit and maternal risk is essential. Serial third-trimester sonographic features suggestive of more severe airway obstruction may justify more aggressive intervention in the right patient. This case study presents a 23-year-old G1P0 with a fetus predicted to have reduced perinatal airway risk based upon serial third-trimester ultrasound findings. Treatment was de-escalated, and the patient was successfully managed. Collaborative data collection aimed at treatment rightsizing across neonatal, maternal, and systematic domains will support ideal allocation.

Fetal and Neonatal Thyroid Dysfunction

Fetal and neonatal dysfunctions include rare serious disorders involving abnormal thyroid function during the second half of gestation, which may persist throughout life, as for most congenital thyroid disorders, or be transient, resolving in the first few weeks of life, as in autoimmune hyperthyroidism or hypothyroidism and some cases of congenital hypothyroidism (CH) with the thyroid gland in situ. Primary CH is diagnosed by neonatal screening, which has been implemented for 40 years in developed countries and should be introduced worldwide, as early treatment prevents irreversible neurodevelopmental delay. Central CH is a rarer entity occurring mostly in association with multiple pituitary hormone deficiencies. Other rare disorders impair the action of thyroid hormones. Neonatal Graves' disease (GD) results from the passage of thyrotropin receptor antibodies (TRAbs) across the placenta, from mother to fetus. It may affect the fetuses and neonates of mothers with a history of current or past GD, but hyperthyroidism develops only in those with high levels of stimulatory TRAb activity. The presence of antibodies predominantly blocking thyroid-stimulating hormone receptors may result in transient hypothyroidism, possibly followed by neonatal hyperthyroidism, depending on the balance between the antibodies present. Antithyroid drugs taken by the mother cross the placenta, treating potential fetal hyperthyroidism, but they may also cause transient fetal and neonatal hypothyroidism. Early diagnosis and treatment are key to optimizing the child's prognosis. This review focuses on the diagnosis and management of these patients during the fetal and neonatal periods. It includes the description of a case of fetal and neonatal autoimmune hyperthyroidism.

Dose-Dependent Influence of Antithyroid Drugs on the Difference in Free Thyroxine Levels between Mothers with Graves' Hyperthyroidism and Their Neonates

BACKGROUND

Several guidelines have recommended that the use of the lowest effective dose of antithyroid drugs (ATDs) that maintains maternal serum free thyroxine (FT4) levels at or moderately above the upper limit of the reference range is appropriate for fetal euthyroid status. However, little is known about whether ATD dosage affects the difference in serum FT4 levels between the mother and neonate. We conducted a retrospective study at a tertiary hospital in Japan to investigate the dose-dependent influence of ATDs on both maternal and fetal thyroid hormone status.

MATERIALS AND METHODS

We retrospectively examined 62 pregnant women who delivered between 2007 and 2016 and were treated for Graves' hyperthyroidism with ATD at any stage during pregnancy. We selected individuals whose data on maternal FT4 level within 4 weeks of their deliveries and cord FT4 level of their infants at the time of delivery were available. Those with multiple pregnancies, iodine or glucocorticoid treatment, and fetal goiter detected by ultrasonography were excluded.

RESULTS

After the exclusion criteria were applied, we recruited 40 individuals. The cord FT4 levels were significantly lower than the maternal FT4 levels in patients treated with high-dosage ATDs (methimazole >5 mg daily or propylthiouracil >100 mg daily). However, there were no significant differences between maternal and cord FT4 levels in patients treated with low-dosage ATDs (methimazole ≤5 mg daily or propylthiouracil ≤100 mg daily). We selected 35 individuals whose data on maternal thyrotropin receptor-binding inhibitory immunoglobulin (TBII) level were available. Multiple linear regression analysis adjusted for ATD dosage, maternal TBII level, and gestational period found that ATD dosage was a significant predictor of the difference in serum FT4 levels between the mother and neonate. In terms of maternal complications, multiple logistic regression analysis identified maternal free triiodothyronine (FT3) level as a significant predictor of the incidence of preterm delivery.

CONCLUSIONS

We found a dose-dependent influence of ATDs on the difference in serum FT4 levels between mothers with Graves' hyperthyroidism and their neonates. Further studies to evaluate the optimal target FT4 and FT3 levels for the mother and neonate during pregnancy may improve the outcome of pregnant women with Graves' hyperthyroidism.

Update on diagnosis and treatment of hyperthyroidism: ultrasonography and functional imaging

Ultrasonography and radionuclide imaging using [^99mTc]Pertechnetate or radioactive iodine isotopes are essential tools used during the diagnostic workup of hyperthyroidism with or without structural alterations of the thyroid. Color duplex sonography and ultrasound elastography may add important information to find the cause of the hormone excess. During the last few years, hybrid imaging using SPECT/-(CT) or PET-based methods, such as [¹²⁴]Iodine-PET/CT or [¹²⁴]Iodine-PET/ultrasound have been increasingly used, playing a role in the context of localizing ectopic thyroid tissue or in multinodular goiter. Recently, promising data has been published on the use of [^99mTc]MIBI imaging in amiodarone induced hyperthyroidism.

Case Report: Functional Analysis and Neuropsychological Evaluation of Dyshormonogenetic Fetal Goiter in Siblings Caused by Novel Compound Hyterozygous TPO Gene Mutations

INTRODUCTION

It is rare for a euthyroid mother to carry a child with a fetal goiter. However, cases of congenital hypothyroidism (CH) caused by thyroid dyshormonogenesis have been reported. Even though gene mutations associated with fetal goiter have been reported in a few studies, the effects on intellectual development have not been investigated. This study aimed to characterize and investigate the underlying genetic mechanism of CH and neuropsychological development and growth of two siblings with CH-induced fetal goiters.

CASE REPORT

Two male siblings from a non-consanguineous marriage with CH and fetal goiter were diagnosed by ultrasonography at 32- and 26-weeks of gestation. This condition was confirmed by cordocentesis in the first pregnancy (TSH: 135 μIU/ml). The mother was euthyroid, and no intra-amniotic levothyroxine treatment was performed. Peripheral blood DNA was screened for TPO mutations. The new deletion p.Cys296Alafs*21 and the p.Arg665Trp mutation, inherited from heterozygous parents, were identified in both patients. Functional analysis showed both mutations reduced the TPO enzyme activity and impaired the membrane localization. The p.Cys296Alafs*21 mutation produces a protein product with a drastically reduced molecular weight. Additionally, a complete clinical and neuropsychological evaluation was also performed. The WISC IV test was employed to provide an overall measure of the siblings' cognitive and intellectual abilities. No growth retardation was detected in either child. In general, both children showed normal neuropsychological development; however, they exhibited slight reduction of Processing Speed Index scores, which are sensitive to neurological and attentional factors and motor maturation activity. Notably, the younger sibling obtained significantly low scores in the Operational Memory Index, a measure of attention capacity and psychoneurological immaturity.

CONCLUSION

We described a new TPO compound heterozygosity that severely impaired the TPO activity and membrane localization leading to severe CH and fetal goiter. This is the first report showing the neuropsychological evaluation in patients with dyshormonogenetic fetal goiter. More studies are needed to understand the neurodevelopmental outcomes of neonates with CH-induced fetal goiters.