We present two pregnant women who attended antenatal care on Thyroxine following definitive treatment for Graves’ disease.
Case 1: A 33 year old, G1 then P0, had received radioactive iodine approximately 12 months before pregnancy. During antenatal care, her TRAB level was 48 IU/L.
Case 2: A 33 year old, G1 then P0, had undergone staged total thyroidectomy approximately three years before pregnancy. Her TRAB level was 85 IU/L.
In both cases, TRAb positivity prompted fetal surveillance and neonatal team involvement. Both neonates were diagnosed with neonatal Graves’ disease within the first week of life after proactive thyroid function screening. They received carbimazole and responded well, with normal growth and development during treatment.
These cases highlight the importance of clarifying the original indication for taking Thyroxine in pregnancy. Previous Graves’ disease may be associated with persistent TRAb positivity despite definitive treatment, including thyroidectomy or radioactive iodine. Maternal TRAb can cross the placenta and stimulate the fetal thyroid, increasing the risk of fetal and neonatal Graves’ disease, fetal growth restriction, prematurity and, in severe untreated cases, fetal loss or neonatal morbidity.
Significantly elevated TRAb, particularly levels greater than three times the assay specific upper limit of normal or above commonly used thresholds such as 5 to 10 IU/L, should prompt fetal surveillance from approximately 18 to 22 weeks’ gestation and neonatal planning.
Conclusion: Prior definitive treatment for Graves’ disease should not reassure clinicians that TRAb is negative. Timely TRAb testing, fetal monitoring and neonatal preparedness are essential.