Central congenital hypothyroidism caused by maternal thyrotoxicosis

Thyroid function and long-term outcomes of children born to mothers with Graves' disease: A 20-year review

AIM

Thyroid dysfunction in infants born to mothers with Graves' disease (GD) is influenced by maternal factors including thyroid status, thyroid-stimulating hormone (TSH) receptor antibody (TRAb) concentration and antithyroid drug use. Thyroid dysfunction during early life could affect growth and development later in life. The aim of this study is to evaluate thyroid function tests (TFTs), and long-term growth and development of children born to mothers with GD.

METHODS

A retrospective chart review of children born to mothers with GD at the Faculty of Medicine Ramathibodi Hospital, Mahidol University, between January 2000 and December 2019 was performed. Clinical data including age of children at enrolment, sex, gestational age, birthweight, maternal thyroid status, maternal TRAb level, maternal GD treatment during pregnancy, neonatal TSH screening and TFT results, and growth and development outcomes of children were collected.

RESULTS

There were 262 children (148 males) enrolled. Twelve (4%) infants had neonatal GD. Five (2%) infants had hypothyroidism requiring levothyroxine treatment: four had secondary hypothyroidism and one patient had congenital primary hypothyroidism. Seven (3%) infants had transient TSH elevation, which fell to normal by 2 weeks of age. The remaining 238 children had normal TFT results. Three out of 12 children with neonatal GD had either delayed growth or development.

CONCLUSIONS

A number of infants born to mothers with GD had abnormal TFTs requiring specific management, and some of them had abnormal growth and development. Careful evaluation of TFTs and long-term follow-up are mandatory for those children.

Follow-Up of Thyroid Function in Children With Neonatal Hyperthyroidism

INTRODUCTION

Neonatal hyperthyroidism mainly occurring in the children born to mothers with Graves' disease (GD). The influence of maternal GD on the newborn's thyroid function includes not only hyperthyroidism, but also various forms of hypothyroidism. Maternally transferred thyrotropin receptor antibodies (TRAb), the antithyroid drug (ATD) administration during pregnancy and previous definitive treatment of GD (radioactive iodine therapy or thyroidectomy) in the mother impact the function of the fetal/neonatal thyroid. Some newborns born to mothers with GD may present central hypothyroidism (CeH) due to impaired regulation of the fetal hypothalamic-pituitary-thyroid axis. The aim of this study was to evaluate different types of thyroid dysfunction in babies with neonatal hyperthyroidism.

MATERIALS AND METHODS

Medical records of 14 infants with neonatal hyperthyroidism (13 born to mothers with GD, and one born to mother with Hashimoto thyroiditis) were analyzed.

RESULTS

Transient hyperthyroidism was the main thyroid dysfunction in our study group. Overt hyperthyroidism with highly increased TRAb levels (mean 13.0 ± 7.0 IU/L) was diagnosed in 6 (43%) neonates. Another 6 (43%) babies presented hyperthyroidism with slightly increased fT4 and/or fT3 levels and TSH levels in the lower limit of the normal range coinciding with positive TRAb levels (mean 3.8 ± 1.6 IU/L). Normal thyroid hormone levels with TSH levels below the lower limit of the range were observed in 2 (14%) neonates. Four babies in the study group (28.5%) required further levothyroxine (L-T4) supplementation due to CeH or, in one case, due to primary hypothyroidism.

CONCLUSION

Our study highlights the need for prolonged monitoring of thyroid function in children born to mothers with GD. Diagnosis of CeH could be delayed due to its masking by transient hyperthyroidism. Prolonged thyroid-stimulating hormone suppression after TRAb elimination should be considered as a signal announcing CeH.