Endocrine Abstracts

Introduction: Neonatal thyrotoxicosis is rare and occurs with transfer of Thyrotropin Receptor Antibodies (TRAb) across the placenta in a mother with a history of Grave’s disease. The neonatal mortality rate can be as high as 20%, usually secondary to cardiac failure. Therefore prompt diagnosis and treatment is essential.

Methods: We report a series of seven infants with neonatal thyrotoxicosis seen in the Endocrine clinic between 2011 and 2015. Maternal Grave’s disease was confirmed as the cause of maternal hyperthyroidism in five of the cases. Data were collected for clinical and biochemical status, antibody status, type and length of treatment and complications of treatment.

Results: Two babies were asymptomatic and did not require any treatment. Other symptoms included jitteriness, agitation and tachycardia (4/5), poor weight gain (2/5), tachypnoea and cardiomegaly (1/5), temperature instability, diarrhoea, and an enlarged spleen (1/5). TRAb antibodies were measured and raised in five babies. TPO antibodies were positive in 3/6 of the babies tested. Treatment with Carbimazole (CBZ) was required in 4/7 babies on average for 57 days. Propranolol was required in 5/7 babies for control of thyrotoxic symptoms. Length of treatment was on average 16 days (range 7–37 days). In babies treated with Carbimazole and/or Propranolol the Free T4 concentrations normalised within 23 days of treatment. TSH normalised on average within 10 weeks of treatment when anti-thyroid treatment was given and within 30 weeks without treatment (2/7 babies). Side effects of CBZ included a florid, macular-papular rash (two babies) and neutropenia (on day 73) was documented in one baby. CBZ was discontinued in this instance.

Discussion/conclusion: Propranolol and CBZ treatment is effective, with improvement in clinical and biochemical status. Despite FT4 normalisation, TSH takes many weeks longer to respond. CBZ side effects do occur and neonates should be monitored closely with appropriate parental counselling and team contact details provided.