Pregnancy after definitive treatment for Graves' disease--does treatment choice influence outcome?

Women requiring thyroid hormone replacement after definitive therapy (surgery or radioiodine) for Graves' disease who later conceive require an early increase in levothyroxine dose and monitoring of thyroid hormone levels throughout pregnancy. In addition, as TSH receptor antibodies (TRAb) can cross the placenta and affect the fetus, measurement of these antibodies during pregnancy is recommended.

To review the management of pregnancies following definitive treatment for Graves' disease in order to assess the rates of maternal hypothyroidism and TRAb measurement.

Retrospective chart review of women who had undergone definitive treatment for Graves' disease at a tertiary hospital and subsequently had one or more pregnancies.

A total of 29 women were identified, each of whom had at least one pregnancy since receiving definitive treatment for Graves' disease: there were a total of 49 pregnancies (22 in the surgical group and 27 in the radioiodine group). Both groups had high rates of hypothyroidism documented during pregnancy (47 and 50%, respectively). The surgical group was more likely to be euthyroid around the time of conception. Less than half of the women were referred to an endocrinologist or had TRAb measured during pregnancy. Neonatal thyroid function was measured in one-third of live births. One case of neonatal thyrotoxicosis was identified.

Adherence to the current American Thyroid Association guidelines is poor. Further education of both patients and clinicians is important to ensure that treatment of women during pregnancy after definitive treatment follows the currently available guidelines.