ESPE Abstracts

Introduction: Neonatal thyrotoxicosis (NT) is rare but potentially life-threatening condition with high mortality risk due to cardiac failure(12-20%). Affected neonates are born to mothers with underlying thyroid pathology. Estimated prevalence of trans-placental transfer of thyroid antibodies occurs 1 in every 70 pregnancies with Graves’ disease. Symptoms in the neonate usually manifest by 10 days of life but this can be as late as day 45. We discuss two cases of NT referred to our tertiary-endocrine unit that highlights management challenges in this rare presentation.

Case 1: A preterm female born at 32+5 weeks was admitted to neonatal unit for respiratory distress requiring ventilator support. Mother was previously treated for Graves’ disease with radioactive iodine. Antenatal scan reported one episode of foetal tachycardia which was treated with carbimazole. On day two of life, thyroid function showed a T4 52.9 pmol/l, no TSH result. She developed tachycardia(202/min) with acute cardio- respiratory deterioration on day five of life, requiring inotropes, HFOV with nitric oxide. Free T4 >100 pmol/l, T3 >32 pmol/l and TSH <0.01 mU/L. Maternal TRAB antibodies in pregnancy were 187.5 IU/ml. Neonate had thyroid storm and therefore was commenced on combination of carbimazole 0.75 mg/kg/day, Propranolol, potassium iodate and prednisolone 1mg/kg. She responded within 48 hrs. All medications were gradually weaned with steroid titration and stopped at 15 weeks of age. Infant is stable on regular follow up monitoring visits and tests.

Case 2: A three-week-old boy referred for poor feeding and weight-loss. Maternal history revealed T1DM, hypothyroidism and coeliac disease. He had clinical signs of tachycardia HR 160/min and constipation. Investigation showed adj-calcium of 3.9 mmol/l, TSH <0.01pmol/l and T4 35.9 pmol/L. He was treated with hyper-hydration and carbimazole of 0.65 mg/kg/day. We observed rapid response within five days of treatment. Carbimazole was stopped on Day 6 but restarted for rebound rise in T4 to 24.4pmol/L. Carbimazole was weaned by 12 weeks of age and patient was safely discharged.

Summary: Although rare, NT poses management challenges as illustrated in our two cases presenting with thyroid storm and hypercalcaemia. Rapid evaluation for associated endocrine dysfunction and initiation of treatment with careful monitoring would prevent adverse outcome. Clinicians should have a high index of suspicion for screening infants born to mothers with underlying thyroid pathology and investigate for associated endocrine conditions that may manifest in the neonatal period.