Endocrine Abstracts

Treatment of hyperthyroidism with antithyroid drugs has recently been shown to have an effect on MMI/Carbimazole embryopathy at a specific early window in gestation. This has important implications for management.

There is agreement that untreated overt gestational hypothyroidism is associated with significant adverse obstetric and fetal/neonatal effects. Although there is also substantial evidence that gestational subclinical hypothyroidism (SCH) is associated with miscarriage, gestational hypertension, preterm delivery and decreased IQ in the offspring, there is a dearth of randomised studies in relation to maternal treatment in pregnancy. In addition there are recent data documenting significant ethnic variation in thyroid function in pregnancy which may affect the calculated incidence of SCH. The associated neuropsychological effects of SCH on the child now include behaviour disorders including ADHD and autism. Moreover, isolated hypothyroxinaemia (IH) is also associated with many of the adverse effects seen with maternal SCH and there is continuing debate as to whether this condition should be treated during gestation. Because of the uncertainties relating to outcomes following L-thyroxine therapy in SCH and IH the question of routine screening for thyroid function in early gestation is still controversial. Published guidelines on thyroid disease and pregnancy in general do not support screening despite the evidence that targeted case finding will miss more than 50% of women with thyroid dysfunction. Results of more randomised studies are awaited but several centres and endocrine societies are already committed to the screening strategy.