Fetal thyrotoxicosis is a rare condition with high morbidity and mortality. It may complicate pregnancies in women with a history of Graves disease (GD) when transplacental passage of maternal TSH receptor antibodies stimulate the fetal thyroid gland and cause hyperthyroidism. We report the case of a 34-year-old woman with a history of GD and prior thyroidectomy, where fetal thyrotoxicosis at 21 weeks of gestation was suspected due to prenatal ultrasound findings of cardiac failure and fetal goiter. She was treated with high-dose carbimazole and followed closely by a multidisciplinary team. Her baby was delivered in good condition at 34 weeks' gestation and developed hyperthyroidism in the days after birth, which was successfully treated medically. This case highlights the importance of awareness of the condition among women with a history of GD, as well as the necessity for prompt diagnosis and treatment of this complex disease.
Keywords: Graves; fetal; hyperthyroidism; pregnancy; thyrotoxicosis.
© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society.