Endocrine Abstracts

Neonatal autoimmune hyperthyroidism is rare but potentially fatal condition. It occurs in 1-5% of infants born to pregnant mothers with Graves’ disease (GD). We present a case of transient neonatal thyrotoxicosis born to pregnant women with GD and high TSH Receptor antibodies. 42 years pregnant lady was referred to Antenatal Endocrine clinic at Walsall Manor Hospital in 15^th week of pregnancy with symptoms of Thyrotoxicosis. She has GD and was taking Propylthiourcil 100 mg twice a day. Her bloods showed supressed TSH with Free T4 60pmol/l. Propylthiouracil was switched to carbimazole 30 mg once daily. Carbimazole dose was uptitrated to 50 mg daily with close monitoring of 1-2 weekly Thyroid functions (TFT’s). Her TSH Receptor Antibody was 39.8IU/l (very high) when tested at 20 weeks of gestation. Examination revealed a large Goitre with no nodules. She has significant Proptosis but no active Thyroid Eye Disease. Neonatal alert was raised and Obstetricians were advised to monitor foetus due to high Maternal TSH receptor antibody levels. She delivered healthy baby via Caesarean at 39 weeks of Gestation. Baby’s TFT’s at 48 hours revealed TSH: 13 miu/l with fT4: 23.1pmol/l. TFT’s at Day 4 revealed TSH 2.3 miu/l with Ft4: 33.4pmol/l. Baby remained well but TFT’s at day 8 indicated worsening Thyrotoxicosis with suppressed TSH and Ft4 54.7pmol/l. Hence Carbimazole was commenced as per Infant’s body weight which swiftly resolved thyrotoxicosis and carbimazole weaned off completely at 4^th week. Although neonatal GD is usually self-limited, it can be severe, life-threatening. Maternal GD is most common cause of neonatal hyperthyroidism. It is important to monitor baby when TSH receptor antibody is 5 times or more in pregnant women with GD. The higher the maternal stimulatory TSHR-Ab during the third trimester, the greater is the likelihood of neonatal GD.