Background and aims Neonatal thyrotoxicosis is a rare condition caused by the transplacental passage of thyroid stimulating immunoglobulins from mothers with Graves’ disease. We report a case of neonatal thyrotoxicosis with concurrent supraventricular tachycardia.

Case Report The female infant, who was born by ceasarean section due to breech delivery and meconium in the amniotic fluid at 36 weeks of gestation, presented with tachycardia on day 7. Her heart rate was between 260–300 beats/minute, and electrocardiogram revealed ongoing supraventricular tachycardia. Sotalol was effective after two cardioversions in maintaining sinus rhytm. Our patient was diagnosed to have thyroid storm due to thyrotoxicosis. Intensive medical therapy was started with 10 mg/kg/day of propylthiouracil, 1 drop of Lugol’s iodine solution three times per day, 2 mg/kg/day propranolol, and 2 mg/kg/day of oral prednisolone. After the diagnosis of neonatal thyrotoxicosis, the mother in our case was found out to have hyperthyroidism with TSH: 0.035 µIU/mL (normal: 0.35- 4.94). She was immediately started methimasole treatment.

Conclusions The purpose of presenting this patient is to emphasise the importance of prenatal care and follow-ups. Obstetricians, endocrinologists, and paediatricians need to work together for better management of Graves’ disease associated pregnancies.